Author: "Ch. Wendel" - Searchworks@Jio Institute Digital Library Search Results

Your search keyword '"Ch. Wendel"' showing total 64 results

Start Over Author "Ch. Wendel"

64 results on '"Ch. Wendel"'

1. Measurement of double polarisation asymmetries in ω-photoproduction

Author: H. Eberhardt, T.C. Jude, H. Schmieden, A.V. Anisovich, B. Bantes, D. Bayadilov, R. Beck, Yu. Beloglazov, M. Bichow, S. Böse, K.-Th. Brinkmann, Th. Challand, V. Crede, F. Diez, P. Drexler, H. Dutz, D. Elsner, R. Ewald, K. Fornet-Ponse, St. Friedrich, F. Frommberger, Ch. Funke, M. Gottschall, A. Gridnev, M. Grüner, E. Gutz, Ch. Hammann, J. Hannappel, J. Hartmann, W. Hillert, Ph. Hoffmeister, Ch. Honisch, I. Jaegle, D. Kaiser, H. Kalinowsky, F. Kalischewski, S. Kammer, I. Keshelashvili, V. Kleber, F. Klein, E. Klempt, K. Koop, B. Krusche, M. Kube, M. Lang, I. Lopatin, Y. Maghrbi, K. Makonyi, V. Metag, W. Meyer, J. Müller, M. Nanova, V. Nikonov, R. Novotny, D. Piontek, S. Reeve, G. Reicherz, T. Rostomyan, S. Runkel, A. Sarantsev, St. Schaepe, Ch. Schmidt, R. Schmitz, T. Seifen, V. Sokhoyan, V. Sumachev, A. Thiel, U. Thoma, M. Urban, H. van Pee, D. Walther, Ch. Wendel, U. Wiedner, A. Wilson, and A. Winnebeck
Subjects: Meson production, Polarisation in interactions and scattering, Light mesons (SCB0), Physics, QC1-999
Abstract: The first measurements of the beam-target-helicity-asymmetries E and G in the photoproduction of ω-mesons off protons at the CBELSA/TAPS experiment are reported. E (G) was measured using circularly (linearly) polarised photons and a longitudinally polarised target. E was measured over the photon energy range from close to threshold (Eγ=1108 MeV) to Eγ=2300 MeV and G at a single energy interval of 1108
Published: 2015
Full Text: View/download PDF

2. Photoproduction of ω mesons off the proton

Author: A. Wilson, V. Crede, A.V. Anisovich, J.C.S. Bacelar, B. Bantes, O. Bartholomy, D. Bayadilov, R. Beck, Y.A. Beloglazov, K.T. Brinkmann, R. Castelijns, H. Dutz, D. Elsner, R. Ewald, F. Frommberger, M. Fuchs, Chr. Funke, R. Gregor, A. Gridnev, E. Gutz, J. Hannappel, W. Hillert, P. Hoffmeister, I. Horn, I. Jaegle, T. Jude, J. Junkersfeld, H. Kalinowsky, V. Kleber, Frank Klein, Friedrich Klein, E. Klempt, M. Kotulla, B. Krusche, M. Lang, H. Löhner, I.V. Lopatin, S. Lugert, T. Mertens, J.G. Messchendorp, V. Metag, M. Nanova, V.A. Nikonov, D. Novinski, R. Novotny, M. Ostrick, L.M. Pant, H. van Pee, M. Pfeiffer, A. Roy, A.V. Sarantsev, C. Schmidt, H. Schmieden, S. Shende, V. Sokhoyan, N. Sparks, A. Süle, V.V. Sumachev, T. Szczepanek, U. Thoma, D. Trnka, R. Varma, D. Walther, Ch. Wendel, and U. Wiedner
Subjects: Meson production, Light mesons, Baryon resonances, Photoproduction reactions, Physics, QC1-999
Abstract: The differential cross sections and unpolarized spin-density matrix elements for the reaction γp→pω were measured using the CBELSA/TAPS experiment for initial photon energies ranging from the reaction threshold to 2.5 GeV. These observables were measured from the radiative decay of the ω meson, ω→π0γ. The cross sections cover the full angular range and show the full extent of the t-channel forward rise. The overall shape of the angular distributions in the differential cross sections and unpolarized spin-density matrix elements are in fair agreement with previous data. In addition, for the first time, a beam of linearly-polarized tagged photons in the energy range from 1150 MeV to 1650 MeV was used to extract polarized spin-density matrix elements. These data were included in the Bonn–Gatchina partial wave analysis (PWA). The dominant contribution to ω photoproduction near threshold was found to be the 3/2+ partial wave, which is primarily due to the sub-threshold N(1720)3/2+ resonance. At higher energies, pomeron-exchange was found to dominate whereas π-exchange remained small. These t-channel contributions as well as further contributions from nucleon resonances were necessary to describe the entire dataset: the 1/2−, 3/2−, and 5/2+ partial waves were also found to contribute significantly.
Published: 2015
Full Text: View/download PDF

3. The polarization observables T, P, and H and their impact on γp→pπ0 multipoles

Author: J. Hartmann, H. Dutz, A.V. Anisovich, D. Bayadilov, R. Beck, M. Becker, Y. Beloglazov, A. Berlin, M. Bichow, S. Böse, K.-Th. Brinkmann, V. Crede, M. Dieterle, H. Eberhardt, D. Elsner, K. Fornet-Ponse, St. Friedrich, F. Frommberger, Ch. Funke, M. Gottschall, A. Gridnev, M. Grüner, St. Goertz, E. Gutz, Ch. Hammann, J. Hannappel, V. Hannen, J. Herick, W. Hillert, Ph. Hoffmeister, Ch. Honisch, O. Jahn, T. Jude, A. Käser, D. Kaiser, H. Kalinowsky, F. Kalischewski, P. Klassen, I. Keshelashvili, F. Klein, E. Klempt, K. Koop, B. Krusche, M. Kube, M. Lang, I. Lopatin, K. Makonyi, F. Messi, V. Metag, W. Meyer, J. Müller, M. Nanova, V. Nikonov, D. Novinski, R. Novotny, D. Piontek, S. Reeve, Ch. Rosenbaum, B. Roth, G. Reicherz, T. Rostomyan, St. Runkel, A. Sarantsev, Ch. Schmidt, H. Schmieden, R. Schmitz, T. Seifen, V. Sokhoyan, Ph. Thämer, A. Thiel, U. Thoma, M. Urban, H. van Pee, D. Walther, Ch. Wendel, U. Wiedner, A. Wilson, A. Winnebeck, and L. Witthauer
Subjects: Baryon spectroscopy, Meson photoproduction, Polarization observables, Multipoles, Physics, QC1-999
Abstract: Data on the polarization observables T, P, and H for the reaction γp→pπ0 are reported. Compared to earlier data from other experiments, our data are more precise and extend the covered range in energy and angle substantially. The results were extracted from azimuthal asymmetries measured using a transversely polarized target and linearly polarized photons. The data were taken at the Bonn electron stretcher accelerator ELSA with the CBELSA/TAPS detector. Within the Bonn-Gatchina partial wave analysis, the new polarization data lead to a significant narrowing of the error band for the multipoles for neutral-pion photoproduction.
Published: 2015
Full Text: View/download PDF

4. Data on Is and Ic in γ→p→pπ0π0 reveal cascade decays of N(1900) via N(1520)π

Author: V. Sokhoyan, E. Gutz, H. van Pee, A.V. Anisovich, J.C.S. Bacelar, B. Bantes, O. Bartholomy, D. Bayadilov, R. Beck, Y. Beloglazov, R. Castelijns, V. Crede, H. Dutz, D. Elsner, R. Ewald, F. Frommberger, M. Fuchs, Ch. Funke, R. Gregor, A. Gridnev, W. Hillert, Ph. Hoffmeister, I. Horn, I. Jaegle, J. Junkersfeld, H. Kalinowsky, S. Kammer, V. Kleber, Frank Klein, Friedrich Klein, E. Klempt, M. Kotulla, B. Krusche, M. Lang, H. Löhner, I. Lopatin, S. Lugert, T. Mertens, J.G. Messchendorp, V. Metag, M. Nanova, V.A. Nikonov, D. Novinski, R. Novotny, M. Ostrick, L. Pant, M. Pfeiffer, D. Piontek, A. Roy, A.V. Sarantsev, Ch. Schmidt, H. Schmieden, S. Shende, A. Süle, V.V. Sumachev, T. Szczepanek, A. Thiel, U. Thoma, D. Trnka, R. Varma, D. Walther, Ch. Wendel, and A. Wilson
Subjects: Physics, QC1-999
Abstract: Photoproduction of two neutral pions off the proton is studied using linearly polarized photons, and the polarization observables Is and Ic are measured for the first time. These two observables are unique to multi-meson final states; they characterize correlations between the linear photon polarization and the direction of outgoing single particles in photoproduction of three-body final states. The Is and Ic distributions suggest that, in the 1.8 to 2.0 GeV mass region, the N(1520)3/2−π intermediate state is reached with reaction dynamics consistent with a dominant JP=3/2+ wave. These data are included in the Bonn–Gatchina (BnGa) partial wave analysis which is based on a large variety of data; the analysis confirms a significant contribution from the reaction chain γp→N(1900)3/2+→N(1520)3/2−π0→pπ0π0. Keywords: Baryon spectroscopy, Double meson photoproduction, Polarization observables
Published: 2015
Full Text: View/download PDF

5. Measurement of polarisation observables in Ks0Σ+ photoproduction off the proton

Author: R. Ewald, A.V. Anisovich, B. Bantes, O. Bartholomy, D. Bayadilov, R. Beck, Y.A. Beloglazov, K.-T. Brinkmann, V. Crede, H. Dutz, D. Elsner, K. Fornet-Ponse, F. Frommberger, Ch. Funke, A.B. Gridnev, E. Gutz, J. Hannappel, W. Hillert, P. Hoffmeister, I. Jaegle, O. Jahn, T.C. Jude, J. Junkersfeld, H. Kalinowsky, S. Kammer, V. Kleber, Frank Klein, Friedrich Klein, E. Klempt, B. Krusche, M. Lang, H. Löhner, I.V. Lopatin, D. Menze, T. Mertens, J.G. Messchendorp, V. Metag, M. Nanova, V.A. Nikonov, D. Novinski, R. Novotny, M. Ostrick, L. Pant, H. van Pee, A. Roy, A.V. Sarantsev, S. Schadmand, C. Schmidt, H. Schmieden, B. Schoch, S. Shende, V. Sokhoyan, A. Süle, V.V. Sumachev, T. Szczepanek, U. Thoma, D. Trnka, R. Varma, D. Walther, and Ch. Wendel
Subjects: Physics, QC1-999
Abstract: The reaction γp→KS0Σ+ is studied in the photon energy range from threshold. Linearly polarised photon beams from coherent bremsstrahlung enabled the first measurement of photon beam asymmetries in this reaction up to Eγ=1650MeV. In addition, the recoil hyperon polarisation was determined through the asymmetry in the weak decay Σ+→pπ0 up to Eγ=2250MeV. The data are compared to partial wave analyses, and the possible impact on the interpretation of a recently observed prominent structure in the cross section near the K⁎ thresholds is discussed. Keywords: Meson production, Other strange mesons, Baryon resonances (SCB0), Decays of baryons, Polarisation in interactions and scattering
Published: 2014
Full Text: View/download PDF

6. Experimental constraints on the ω–nucleus real potential

Author: S. Friedrich, K. Makonyi, V. Metag, D. Bayadilov, B. Bantes, R. Beck, Y.A. Beloglazov, S. Böse, K.-T. Brinkmann, Th. Challand, V. Crede, T. Dahlke, F. Dietz, P. Drexler, H. Eberhardt, D. Elsner, R. Ewald, K. Fornet-Ponse, F. Frommberger, Ch. Funke, M. Gottschall, A. Gridnev, M. Grüner, E. Gutz, Ch. Hammann, D. Hammann, J. Hannappel, J. Hartmann, W. Hillert, S. Hirenzaki, P. Hoffmeister, Ch. Honisch, I. Jaegle, D. Kaiser, H. Kalinowsky, S. Kammer, I. Keshelashvili, V. Kleber, F. Klein, B. Krusche, M. Lang, I.V. Lopatin, Y. Maghrbi, M. Nanova, H. Nagahiro, J. Müller, T. Odenthal, D. Piontek, T. Rostomyan, S. Schaepe, Ch. Schmidt, H. Schmieden, R. Schmitz, T. Seifen, A. Thiel, U. Thoma, H. van Pee, D. Walther, J. Weil, Ch. Wendel, U. Wiedner, A. Wilson, A. Winnebeck, and F. Zenke
Subjects: Physics, QC1-999
Abstract: In a search for ω mesic states, the production of ω-mesons in coincidence with forward going protons has been studied in photon induced reactions on 12C for incident photon energies of 1250–3100 MeV. The π0γ pairs from decays of bound or quasi-free ω-mesons have been measured with the CBELSA/TAPS detector system in coincidence with protons registered in the MiniTAPS forward array. Structures in the total energy distribution of the π0γ pairs, which would indicate the population and decay of bound ω 11B states, are not observed. The π0γ cross section of 0.3 nb MeV−1 sr−1 observed in the bound state energy regime between −100 and 0 MeV may be accounted for by yield leaking into the bound state regime because of the large in-medium width of the ω-meson. A comparison of the measured total energy distribution with calculations suggests the real part V0 of the ω 11B potential to be small and only weakly attractive with V0(ρ=ρ0)=−15±35(stat)±20(syst) MeV in contrast to some theoretical predictions of attractive potentials with a depth of 100–150 MeV.
Published: 2014
Full Text: View/download PDF

7. Observation of a structure in the $$M_{p\eta }$$ invariant mass distribution near 1700 $$\hbox {MeV}/\hbox {c}^2$$ in the $$\gamma \mathbf {p \rightarrow p \pi ^0 \eta } $$ reaction

Author: V. Metag, M. Nanova, J. Hartmann, P. Mahlberg, F. Afzal, C. Bartels, D. Bayadilov, R. Beck, M. Becker, E. Blanke, K.-T. Brinkmann, S. Ciupka, V. Crede, M. Dieterle, H. Dutz, D. Elsner, F. Frommberger, A. Gridnev, M. Gottschall, M. Grüner, Ch. Hammann, J. Hannappel, W. Hillert, J. Hoff, Ph. Hoffmeister, Ch. Honisch, T. Jude, H. Kalinowsky, F. Kalischewski, I. Keshelashvili, B. Ketzer, P. Klassen, F. Klein, K. Koop, P. Kroenert, B. Krusche, M. Lang, I. Lopatin, F. Messi, W. Meyer, B. Mitlasóczky, J. Müller, J. Müllers, V. Nikonov, V. Novinsky, R. Novotny, D. Piontek, G. Reicherz, L. Richter, T. Rostomyan, S. Runkel, B. Salisbury, A. Sarantsev, D. Schaab, Ch. Schmidt, H. Schmieden, J. Schultes, T. Seifen, V. Sokhoyan, C. Sowa, K. Spieker, N. Stausberg, A. Thiel, U. Thoma, T. Triffterer, M. Urban, G. Urff, H. van Pee, M. Wagner, D. Walther, Ch. Wendel, D. Werthmüller, U. Wiedner, A. Wilson, A. Winnebeck, L. Witthauer, and Y. Wunderlich
Subjects: Nuclear and High Energy Physics
Published: 2021
Full Text: View/download PDF

8. Measurement of the helicity asymmetry E for the reaction $$ \gamma p\rightarrow \pi ^0 p$$

Author: H. Schmieden, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, T. Rostomyan, M. Gottschall, M. Urban, V. Sokhoyan, D. Walther, M. Dieterle, T. Seifen, Ch. Hammann, A. Thiel, A. Winnebeck, Frank Frommberger, Matthew Lang, M. Kube, I. Keshelashvili, J. Hannappel, A. V. Anisovich, Jörg H. Müller, Jens Hartmann, V. Crede, Lilian Witthauer, Ulrich Wiedner, U. Thoma, P. Mahlberg, G. Reicherz, Frank Klein, V. Metag, Y. Wunderlich, K. Koop, K. Spieker, A. V. Sarantsev, A. Wilson, M. Bichow, Ch. Honisch, Ch. Schmidt, S. Friedrich, K. Makonyi, R. Beck, H. Dutz, K.-Th. Brinkmann, H. van Pee, P. Klassen, H. Eberhardt, D. Werthmüller, M. Grüner, S. Kammer, F. Dietz, R. Ewald, F. Afzal, H. Kalinowsky, E. Gutz, D. Piontek, I. V. Lopatin, T. C. Jude, Wolfgang Hillert, Ch. Wendel, D. Elsner, R. W. Novotny, Ph. Hoffmeister, V. A. Nikonov, J. Müllers, Eberhard Klempt, B. Krusche, W. Meyer, and K. Fornet-Ponse
Subjects: Nuclear physics, Physics, Nuclear and High Energy Physics, Photon, media_common.quotation_subject, Hadron, Bremsstrahlung, Nuclear fusion, Electron, Photon energy, Helicity, Asymmetry, media_common
Abstract: A measurement of the double-polarization observable E for the reaction $$\gamma p\rightarrow \pi ^0 p$$ γ p → π 0 p is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C$$_4$$ 4 H$$_9$$ 9 OH) target, which provided longitudinally-polarized protons. Circularly-polarized photons were produced via bremsstrahlung of longitudinally-polarized electrons. The data cover the photon energy range from $$E_\gamma =600$$ E γ = 600 to 2310 MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses.
Published: 2021
Full Text: View/download PDF

9. Observation of the pη′ Cusp in the New Precise Beam Asymmetry Σ Data for γp→pη

Author: Cbelsa, F. Afzal, L Richter, S. Ciupka, U-G Meißner, V. Metag, W. Meyer, M. Grüner, K. Koop, T. Seifen, Lilian Witthauer, H. Kalinowsky, Matthew Lang, D. Piontek, N. Stausberg, M. Urban, I. V. Lopatin, A. V. Sarantsev, T. C. Jude, Frank Frommberger, M. Becker, B. Mitlasóczki, H. Schmieden, M. Dieterle, V. Sokhoyan, H. van Pee, D. E. Bayadilov, P. Klassen, K. Spieker, K. Nikonov, B. Krusche, A. B. Gridnev, Mariana Nanova, B. Salisbury, Wolfgang Hillert, J. Hannappel, C. Sowa, J. Hoff, E. Gutz, Ch. Honisch, J. Schultes, H. Dutz, G. Urff, Ch. Schmidt, Y. Wunderlich, Ulrich Wiedner, Frank Klein, V. Crede, U. Thoma, D. Elsner, S. Friedrich, A. Wilson, R. W. Novotny, Ph. Hoffmeister, A. Thiel, V. Novinskiy, P. Mahlberg, A. V. Anisovich, Francesco Messi, I. Keshelashvili, Ch. Wendel, F. Kalischewski, K.-T. Brinkmann, T. Triffterer, P. Kroenert, G. Reicherz, D. Walther, Jörg H. Müller, Jens Hartmann, D. Rönchen, T. Rostomyan, M. Gottschall, E. Blanke, D. Schaab, R. Beck, Ch. Hammann, A. Winnebeck, J. Müllers, Eberhard Klempt, and V. A. Nikonov
Subjects: Physics, Photon, Meson, media_common.quotation_subject, Partial wave analysis, Nuclear Theory, Solid angle, General Physics and Astronomy, Observable, Polarization (waves), 01 natural sciences, Asymmetry, Nuclear physics, 0103 physical sciences, Physics::Accelerator Physics, Nuclear Experiment, 010306 general physics, Nucleon, media_common
Abstract: Data on the beam asymmetry Σ in the photoproduction of η mesons off protons are reported for tagged photon energies from 1130 to 1790 MeV (mass range from W=1748 MeV to W=2045 MeV). The data cover the full solid angle that allows for a precise moment analysis. For the first time, a strong cusp effect in a polarization observable has been observed that is an effect of a branch-point singularity at the pη^{'} threshold [E_{γ}=1447 MeV (W=1896 MeV)]. The latest BnGa partial wave analysis includes the new beam asymmetry data and yields a strong indication for the N(1895)1/2^{-} nucleon resonance, demonstrating the importance of including all singularities for a correct determination of partial waves and resonance parameters.
Published: 2020
Full Text: View/download PDF

10. Observation of the p η ′ Cusp in the New Precise Beam Asymmetry Σ Data for γ p → p η

Author: F, Afzal, Y, Wunderlich, A V, Anisovich, D, Bayadilov, R, Beck, M, Becker, E, Blanke, K-Th, Brinkmann, S, Ciupka, V, Crede, M, Dieterle, H, Dutz, D, Elsner, S, Friedrich, F, Frommberger, A, Gridnev, M, Gottschall, M, Grüner, E, Gutz, C, Hammann, J, Hannappel, J, Hartmann, W, Hillert, J, Hoff, P, Hoffmeister, C, Honisch, T, Jude, H, Kalinowsky, F, Kalischewski, I, Keshelashvili, P, Klassen, F, Klein, E, Klempt, K, Koop, P, Kroenert, B, Krusche, M, Lang, I, Lopatin, P, Mahlberg, U-G, Meißner, F, Messi, V, Metag, W, Meyer, B, Mitlasóczki, J, Müller, J, Müllers, M, Nanova, K, Nikonov, V, Nikonov, V, Novinskiy, R, Novotny, D, Piontek, G, Reicherz, L, Richter, D, Rönchen, T, Rostomyan, B, Salisbury, A, Sarantsev, D, Schaab, C, Schmidt, H, Schmieden, J, Schultes, T, Seifen, V, Sokhoyan, C, Sowa, K, Spieker, N, Stausberg, A, Thiel, U, Thoma, T, Triffterer, M, Urban, G, Urff, H, van Pee, D, Walther, Ch, Wendel, U, Wiedner, A, Wilson, A, Winnebeck, and L, Witthauer
Subjects: Nuclear Theory, Physics::Accelerator Physics, ddc:530, Nuclear Experiment
Abstract: Data on the beam asymmetry Σ in the photoproduction of η mesons off protons are reported for tagged photon energies from 1130 to 1790 MeV (mass range from W=1748 MeV to W=2045 MeV). The data cover the full solid angle that allows for a precise moment analysis. For the first time, a strong cusp effect in a polarization observable has been observed that is an effect of a branch-point singularity at the pη^{'} threshold [E_{γ}=1447 MeV (W=1896 MeV)]. The latest BnGa partial wave analysis includes the new beam asymmetry data and yields a strong indication for the N(1895)1/2^{-} nucleon resonance, demonstrating the importance of including all singularities for a correct determination of partial waves and resonance parameters.
Published: 2020
Full Text: View/download PDF

11. Measurement of the helicity asymmetry

Author: M, Gottschall, F, Afzal, A V, Anisovich, D, Bayadilov, R, Beck, M, Bichow, K Th, Brinkmann, V, Crede, M, Dieterle, F, Dietz, H, Dutz, H, Eberhardt, D, Elsner, R, Ewald, K, Fornet-Ponse, St, Friedrich, F, Frommberger, A, Gridnev, M, Grüner, E, Gutz, Ch, Hammann, J, Hannappel, J, Hartmann, W, Hillert, Ph, Hoffmeister, Ch, Honisch, T, Jude, S, Kammer, H, Kalinowsky, I, Keshelashvili, P, Klassen, F, Klein, E, Klempt, K, Koop, B, Krusche, M, Kube, M, Lang, I, Lopatin, P, Mahlberg, K, Makonyi, V, Metag, W, Meyer, J, Müller, J, Müllers, M, Nanova, V, Nikonov, R, Novotny, D, Piontek, G, Reicherz, T, Rostomyan, A, Sarantsev, Ch, Schmidt, H, Schmieden, T, Seifen, V, Sokhoyan, K, Spieker, A, Thiel, U, Thoma, M, Urban, H van, Pee, D, Walther, Ch, Wendel, D, Werthmüller, U, Wiedner, A, Wilson, A, Winnebeck, L, Witthauer, and Y, Wunderlich
Subjects: Regular Article – Experimental Physics
Abstract: A measurement of the double-polarization observable E for the reaction \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma p\rightarrow \pi ^0 p$$\end{document}γp→π0p is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_4$$\end{document}4H\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_9$$\end{document}9OH) target, which provided longitudinally-polarized protons. Circularly-polarized photons were produced via bremsstrahlung of longitudinally-polarized electrons. The data cover the photon energy range from \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$E_\gamma =600$$\end{document}Eγ=600 to 2310 MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses.
Published: 2019

12. New data on γ→p→→ηp with polarized photons and protons and their implications for N⁎ → Nη decays

Author: P. Klassen, V. Hannen, J. Herick, Reinhard Beck, Ch. Wendel, S. Kammer, Jens Hartmann, V. Metag, H. van Pee, F. Dietz, P. Mahlberg, Ch. Honisch, Ch. Schmidt, Th. Challand, S. Böse, T. C. Jude, H. Kalinowsky, M. Bichow, K. Koop, T. Rostomyan, M. Becker, I. Jaegle, G. Reicherz, A. Berlin, A. Käser, Friedrich Klein, M. Gottschall, D. Kaiser, A. Wilson, R. Schmitz, T. Seifen, R. Ewald, C. Rosenbaum, Yasser Maghrbi, F. Afzal, H. Dutz, O. Jahn, H. Eberhardt, D. Elsner, A. Thiel, R. W. Novotny, Ph. Hoffmeister, V. Crede, S. Goertz, A. V. Anisovich, J. Müller, H. Schmieden, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, M. Grüner, B. Roth, Frank Frommberger, Matthew Lang, S. Friedrich, K. Makonyi, Francesco Messi, B. Bantes, J. Hannappel, Wolfgang Hillert, M. Kube, E. Gutz, Ulrich Wiedner, M. Urban, V. Kleber, U. Thoma, V. Sokhoyan, F. Kalischewski, I. Keshelashvili, W. Meyer, J. Müllers, Eberhard Klempt, K. Fornet-Ponse, C. Funke, D. V. Novinski, Lilian Witthauer, Ch. Hammann, B. Krusche, P. Drexler, A. Winnebeck, V. A. Nikonov, M. Dieterle, K.-T. Brinkmann, Yu. A. Beloglazov, A. V. Sarantsev, D. Piontek, I. V. Lopatin, and D. Walther
Subjects: Physics, Nuclear physics, Nuclear and High Energy Physics, Photon, Meson, 010308 nuclear & particles physics, 0103 physical sciences, Polarization observables, Solid angle, 010306 general physics, Branching (polymer chemistry), Nucleon, 01 natural sciences
Abstract: The polarization observables T , E , P , H , and G in photoproduction of η mesons off protons are measured for photon energies from threshold to W = 2400 MeV (T), 2280 MeV (E), 1620 MeV ( P , H ), or 1820 MeV (G), covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, JuBo, and BnGa partial-wave analyses. A refit within the BnGa approach including further data yields precise branching ratios for the Nη decay of nucleon resonances. A Nη-branching ratio of 0.33 ± 0.04 for N ( 1650 ) 1 / 2 − is found, which reduces the large and controversially discussed Nη-branching ratio difference of the two lowest mass J P = 1 / 2 − -resonances significantly.
Published: 2020
Full Text: View/download PDF

13. The $\eta^{\prime}$ η -carbon potential at low meson momenta

Author: D. Elsner, K. Koop, Frank Frommberger, V. Metag, Ph. Hoffmeister, J. Müller, B. Krusche, E. Gutz, D. Kaiser, K.-T. Brinkmann, T. Triffterer, C. Sowa, J. Müllers, A. Wilson, S. Friedrich, T. Seifen, Matthew Lang, J. Hannappel, B. Bantes, Francesco Messi, Ulrich Wiedner, E. Ya. Paryev, U. Thoma, D. Walther, Jens Hartmann, F. Afzal, Ch. Hammann, Reinhard Beck, P. Drexler, V. Crede, Ch. Honisch, Y. Wunderlich, D. Piontek, Ch. Schmidt, Hans-Georg Zaunick, H. Eberhardt, T. C. Jude, M. Becker, Ch. Funke, Ch. Wendel, D. Werthmüller, Wolfgang Hillert, M. Grüner, I. Keshelashvili, T. Rostomyan, Lilian Witthauer, M. Gottschall, S. Böse, K. Makonyi, M. Urban, V. Sokhoyan, H. van Pee, Friedrich Klein, K. Spieker, D. Schaab, R. Schmitz, A. Thiel, F. Kalischewski, H. Schmieden, D. E. Bayadilov, and Mariana Nanova
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Meson, 010308 nuclear & particles physics, Hadron, Carbon-12, Elementary particle, 01 natural sciences, Baryon, 0103 physical sciences, High Energy Physics::Experiment, Production (computer science), Nuclear Experiment, 010306 general physics, Nucleon, Boson
Abstract: The production of $\eta^{\prime}$ mesons in coincidence with forward-going protons has been studied in photon-induced reactions on 12C and on a liquid hydrogen (LH2) target for incoming photon energies of 1.3-2.6 GeV at the electron accelerator ELSA. The $\eta^{\prime}$ mesons have been identified via the $\eta^{\prime} \rightarrow \pi^{0} \pi^{0}\eta \rightarrow 6 \gamma$ decay registered with the CBELSA/TAPS detector system. Coincident protons have been identified in the MiniTAPS BaF2 array at polar angles of $2^{\circ} \le \theta_{p} \le 11^{\circ}$ . Under these kinematic constraints the $\eta^{\prime}$ mesons are produced with relatively low kinetic energy ( $\approx 150$ MeV) since the coincident protons take over most of the momentum of the incident-photon beam. For the C-target this allows the determination of the real part of the $\eta^{\prime}$ -carbon potential at low meson momenta by comparing with collision model calculations of the $\eta^{\prime}$ kinetic energy distribution and excitation function. Fitting the latter data for $\eta^{\prime}$ mesons going backwards in the center-of-mass system yields a potential depth of $V = -(44 \pm 16(stat) \pm 15(syst))$ MeV, consistent with earlier determinations of the potential depth in inclusive measurements for average $\eta^{\prime}$ momenta of $\approx 1.1$ GeV/c. Within the experimental uncertainties, there is no indication of a momentum dependence of the $\eta^{\prime}$ -carbon potential. The LH2 data, taken as a reference to check the data analysis and the model calculations, provide differential and integral cross sections in good agreement with previous results for $\eta^{\prime}$ photoproduction off the free proton.
Published: 2018
Full Text: View/download PDF

14. Photoproduction of $ \eta{^\prime}$ -mesons off the deuteron

Author: S. Lugert, D. Walther, S. Hoeffgen, D. Trnka, I. Jaegle, M. Ostrick, Eberhard Klempt, A. V. Anisovich, Matthew Lang, U. Thoma, Kanzo Nakayama, T. Szczepanek, D. Menze, V. Metag, J. Junkersfeld, Fei Huang, V. Kleber, Wolfgang Hillert, V. Crede, H. Loehner, H. van Pee, Yu. A. Beloglazov, A. V. Sarantsev, T. Mertens, D. V. Novinski, S. Kammer, J. C. S. Bacelar, R. Gregor, R. Castelijns, V. A. Nikonov, M. Kotulla, C. Funke, L. Tiator, R. Ewald, O. Bartholomy, D. Elsner, Lalit Mohan Pant, R. Varma, Friedrich Klein, H. Dutz, Ch. Wendel, B. Krusche, Ch. Schmidt, R. W. Novotny, A. Suele, V. V. Sumachev, J. G. Messchendorp, S. Shende, B. Schoch, A. Fix, H. Kalinowsky, V. Sokhoyan, I. V. Lopatin, H. Schmieden, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, R. Beck, S. Schadmand, Ankhi Roy, E. Gutz, B. Bantes, Frank Frommberger, Frank Klein, and M. Pfeiffer
Subjects: Physics, Nuclear and High Energy Physics, Photon, Proton, Meson, Nuclear Theory, Particle accelerator, law.invention, Nuclear physics, Recoil, Deuterium, law, Neutron, High Energy Physics::Experiment, Nucleon, Nuclear Experiment
Abstract: Quasi-free photoproduction of $ \eta{^\prime}$ -mesons off nucleons bound in the deuteron has been measured with the combined Crystal Barrel - TAPS detector. The experiment was done at a tagged photon beam of the ELSA electron accelerator in Bonn for incident photon energies from the production threshold up to 2.5GeV. The $ \eta{^\prime}$ -mesons have been detected in coincidence with recoil protons and recoil neutrons. The quasi-free proton data are in good agreement with the results for free protons, indicating that nuclear effects have no significant impact. The coincidence with recoil neutrons provides the first data for the $ \gamma$ n $ \rightarrow$ n $ \eta{^\prime}$ reaction. In addition, also first estimates for coherent $ \eta{^\prime}$ -production off the deuteron have been obtained. In agreement with model predictions, the total cross-section for this channel is found to be very small, at most at the level of a few nb. The data are compared to model calculations taking into account contributions from nucleon resonances and t -channel exchanges
Published: 2018

15. Photoproduction of η -mesons off nuclei for Eγ ⩽ 2.2 GeV

Author: Lalit Mohan Pant, B. Bantes, M. Pfeiffer, D. Menze, R. Ewald, S. Hoeffgen, Ankhi Roy, Ch. Wendel, V. V. Sumachev, H. Kalinowsky, Matthew Lang, A. Ehmanns, R. Varma, D. Elsner, I. Jaegle, S. Kammer, R. Castelijns, H. Dutz, S. Shende, V. Sokhoyan, S. Lugert, D. Trnka, B. Krusche, R. W. Novotny, Ph. Hoffmeister, K. Essig, J. Langheinrich, T. Szczepanek, A. Suele, O. Bartholomy, S. Schadmand, Ulrich Mosel, R. Gregor, Yu. A. Beloglazov, M. Konrad, R. W. Gothe, Eberhard Klempt, J. C. S. Bacelar, M. Kotulla, C.-H. Weinheimer, B. Schoch, C. Morales, M. Ostrick, I. Fabry, Michael Fuchs, R. Beck, E. Gutz, J. Lotz, V. Metag, V. Crede, Ch. Schmidt, Frank Klein, Friedrich Klein, V. Kleber, H. Schmieden, I. V. Lopatin, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, H. van Pee, D. V. Novinski, J. G. Messchendorp, K. Fornet-Ponse, D. Walther, C. Funke, I. Horn, A. Radkov, T. Mertens, U. Thoma, P. Muehlich, J. Junkersfeld, and H. Loehner
Subjects: Mass number, Physics, Nuclear and High Energy Physics, Meson, Nuclear Theory, Nuclear matter, Resonance (particle physics), Nuclear physics, Pion, Production (computer science), High Energy Physics::Experiment, Absorption (logic), Nucleon, Nuclear Experiment
Abstract: Photoproduction of $\eta$ mesons off $^{12}$C, $^{40}$Ca, $^{93}$Nb, and $^{nat}$Pb nuclei has been measured with a tagged photon beam with energies between 0.6 and 2.2 GeV. The experiment was performed at the Bonn ELSA accelerator with the combined setup of the Crystal Barrel and TAPS calorimeters. It aimed at the in-medium properties of the S$_{11}$(1535) nucleon resonance and the study of the absorption properties of nuclear matter for $\eta$ mesons. Careful consideration was given to contributions from $\eta\pi$ final states and secondary production mechanisms of $\eta$-mesons e.g. from inelastic $\pi N$ reactions of intermediate pions. The analysis of the mass number scaling shows that the nuclear absorption cross section $\sigma_{N\eta}$ for $\eta$ mesons is constant over a wide range of the $\eta$ momentum. The comparison of the excitation functions to data off the deuteron and to calculations in the framework of a BUU-model show no unexplained in-medium modifications of the S$_{11}$(1535)., Comment: Accepted for publication in Eur. Phys. J. A
Published: 2018

16. Measurement of double polarisation asymmetries in ω -photoproduction

Author: Frank Frommberger, V. Metag, F. Diez, M. Bichow, Ch. Hammann, T. Seifen, I. Jaegle, F. Kalischewski, D. Elsner, M. Kube, V. Crede, P. Drexler, A. Winnebeck, K. Fornet-Ponse, H. Schmieden, J. Müller, R. W. Novotny, B. Bantes, D. Walther, Ph. Hoffmeister, D. E. Bayadilov, K. Koop, U. Thoma, A. B. Gridnev, Mariana Nanova, S. Böse, A. Wilson, Yasser Maghrbi, H. Kalinowsky, Eberhard Klempt, H. Dutz, J. Hannappel, S. Runkel, H. Eberhardt, R. Ewald, Ulrich Wiedner, W. Meyer, St. Schaepe, V. A. Nikonov, T. Rostomyan, I. Keshelashvili, R. Schmitz, B. Krusche, Ch. Honisch, M. Grüner, Ch. Schmidt, A. Thiel, S. Friedrich, G. Reicherz, M. Gottschall, Friedrich Klein, Ch. Wendel, V. V. Sumachev, Wolfgang Hillert, R. Beck, Jens Hartmann, E. Gutz, S. Kammer, Th. Challand, Ch. Funke, K. Makonyi, Matthew Lang, K.-Th. Brinkmann, D. Kaiser, S. Reeve, H. van Pee, V. Kleber, D. Piontek, I. V. Lopatin, T. C. Jude, Yu. A. Beloglazov, A. V. Sarantsev, A. V. Anisovich, M. Urban, and V. Sokhoyan
Subjects: Physics, Nuclear and High Energy Physics, Photon, Meson, Partial wave analysis, Meson production, Resonance, Photon energy, Helicity, Omega, lcsh:QC1-999, Light mesons (SCB0), Nuclear physics, Baryon, Polarisation in interactions and scattering, Light mesons (SCB0), Nuclear Experiment, lcsh:Physics
Abstract: The first measurements of the beam-target-helicity-asymmetries $E$ and $G$ in the photoproduction of $\omega$-mesons off protons at the CBELSA/TAPS experiment are reported. $E$ ($G$) was measured using circularly (linearly) polarised photons and a longitudinally polarised target. $E$ was measured over the photon energy range from close to threshold ($E_\gamma = 1108$~MeV) to $E_\gamma = 2300$~MeV and $G$ at a single energy interval of $1108 < E_\gamma, Comment: 6 pages, 6 figures
Published: 2015
Full Text: View/download PDF

17. The polarization observables T , P , and H and their impact onγp→pπ0multipoles

Author: Ph. Thämer, Reinhard Beck, M. Grüner, V. Hannen, Matthew Lang, J. Herick, B. Roth, Ch. Honisch, Ch. Schmidt, K. Makonyi, K.-Th. Brinkmann, S. Reeve, H. van Pee, Eberhard Klempt, D. V. Novinski, Yu. A. Beloglazov, D. Elsner, M. Becker, Ch. Wendel, V. Crede, A. V. Sarantsev, S. Friedrich, W. Meyer, V. Metag, F. Kalischewski, Francesco Messi, R. W. Novotny, B. Krusche, Ph. Hoffmeister, St. Goertz, Lilian Witthauer, A. Käser, V. A. Nikonov, D. Piontek, I. V. Lopatin, A. V. Anisovich, J. Hannappel, P. Klassen, T. C. Jude, M. Urban, M. Dieterle, Ulrich Wiedner, V. Sokhoyan, A. Thiel, U. Thoma, Ch. Funke, Wolfgang Hillert, M. Bichow, H. Schmieden, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, K. Fornet-Ponse, S. Böse, Ch. Hammann, H. Kalinowsky, D. Walther, A. Winnebeck, A. Wilson, T. Seifen, Frank Frommberger, M. Kube, K. Koop, G. Reicherz, Friedrich Klein, R. Schmitz, O. Jahn, J. Müller, Ch. Rosenbaum, H. Dutz, H. Eberhardt, E. Gutz, I. Keshelashvili, St. Runkel, A. Berlin, T. Rostomyan, D. Kaiser, M. Gottschall, and Jens Hartmann
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Photon, Linear polarization, media_common.quotation_subject, Partial wave analysis, Electron, Polarization (waves), Asymmetry, Nuclear physics, Nuclear Experiment, Nucleon, Multipole expansion, media_common
Abstract: Data on the polarization observables T, P, and H for the reaction gamma p -> p pi(0) are reported. Compared to earlier data from other experiments, our data are more precise and extend the covered range in energy and angle substantially. The results were extracted from azimuthal asymmetries measured using a transversely polarized target and linearly polarized photons. The data were taken at the Bonn electron stretcher accelerator ELSA with the CBELSA/TAPS detector. Within the Bonn-Gatchina partial wave analysis, the new polarization data lead to a significant narrowing of the error band for the multipoles for neutral-pion photoproduction. (C) 2015 The Authors. Published by Elsevier B.V.
Published: 2015
Full Text: View/download PDF

18. Data onIsandIcinγ→p→pπ0π0reveal cascade decays ofN(1900)viaN(1520)π

Author: H. Schmieden, D. E. Bayadilov, Mariana Nanova, M. Pfeiffer, Y. Beloglazov, H. Dutz, A. Suele, D. Walther, E. Gutz, D. Piontek, V. Crede, T. Szczepanek, J. C. S. Bacelar, A. V. Sarantsev, I. V. Lopatin, Matthew Lang, Frank Frommberger, Lalit Mohan Pant, M. Fuchs, V. Kleber, R. Gregor, Friedrich Klein, A. Gridnev, V. Metag, M. Kotulla, V. Sokhoyan, A. V. Anisovich, Ch. Schmidt, U. Thoma, A. Thiel, R. Ewald, M. Ostrick, S. Kammer, S. Lugert, J. G. Messchendorp, J. Junkersfeld, T. Mertens, Herbert Löhner, Eberhard Klempt, Ch. Funke, I. Jaegle, D. Trnka, R. Varma, B. Bantes, V. A. Nikonov, I. Horn, R. Beck, R. Castelijns, D. V. Novinski, B. Krusche, H. Kalinowsky, Ankhi Roy, Ch. Wendel, V. V. Sumachev, Wolfgang Hillert, D. Elsner, R. W. Novotny, Ph. Hoffmeister, O. Bartholomy, H. van Pee, S. Shende, Frank Klein, and A. Wilson
Subjects: Baryon, Physics, Nuclear physics, Nuclear and High Energy Physics, Pion, Photon, Linear polarization, Partial wave analysis, Photon polarization, Pi, Dalitz plot
Abstract: Photoproduction of two neutral pions off the proton is studied using linearly polarized photons, and the polarization observables I-s and I-c are measured for the first time. These two observables are unique to multi-meson final states; they characterize correlations between the linear photon polarization and the direction of outgoing single particles in photoproduction of three-body final states. The I-s and I-c distributions suggest that, in the 1.8 to 2.0 GeV mass region, the N(1520) 3/2(-)pi intermediate state is reached with reaction dynamics consistent with a dominant J(P) = 3/2(+) wave. These data are included in the Bonn-Gatchina (BnGa) partial wave analysis which is based on a large variety of data; the analysis confirms a significant contribution from the reaction chain gamma p -> N(1900)3/2(+) -> N(1520)3/2(-)pi(0) -> p pi(0)pi(0). (C) 2015 The Authors. Published by Elsevier B.V.
Published: 2015
Full Text: View/download PDF

19. Photoproduction of eta mesons from the neutron: cross sections and double polarization observable E

Author: Ch. Hammann, V. Metag, A. Winnebeck, M. Grüner, Wolfgang Hillert, T. Seifen, J. Müllers, T. Rostomyan, A. V. Anisovich, M. Gottschall, Frank Klein, K. Koop, Friedrich, M. Bichow, D. Elsner, B. Bantes, Jörg H. Müller, D. Piontek, M. Dieterle, Frank Frommberger, I. V. Lopatin, Jens Hartmann, V. Crede, R. Beck, Alastair J. Wilson, T. C. Jude, Ph. Hoffmeister, Suvadeep Bose, V. A. Nikonov, A. V. Sarantsev, E. Gutzınst, Ch. Honisch, Ch. Schmidt, B. Krusche, N. K. Walford, V. Kleber, Lilian Witthauer, D. Hammann, A. Käser, P. Klassen, K. Makonyi, Matthew Lang, H. van Pee, F. Kalischewski, D. Kaiser, S. Kammer, H. Schmieden, D. E. Bayadilov, H. Dutz, A. B. Gridnev, Mariana Nanova, Th. Challand, Ch. Funke, H. Kalinowsky, P. Mahlberg, H. Eberhardt, J. Hannappel, Goertz, Ch. Wendel, D. Werthmüller, U. Thoma, K. Fornet-Ponse, W. Meyer, M. Urban, V. Sokhoyan, K. Spieker, G. Reicherz, I. Keshelashvili, R. Ewald, A. Thiel, F. Afzal, D. Walther, and K.-T. Brinkmann
Subjects: Excitation function, Physics, Nuclear and High Energy Physics, Meson, 010308 nuclear & particles physics, media_common.quotation_subject, Nuclear Theory, FOS: Physical sciences, Observable, Polarization (waves), 01 natural sciences, Helicity, Asymmetry, Nuclear physics, Deuterium, 0103 physical sciences, ddc:530, High Energy Physics::Experiment, Neutron, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, media_common
Abstract: Photoproduction of $\eta$ mesons from neutrons} \abstract{Results from measurements of the photoproduction of $\eta$ mesons from quasifree protons and neutrons are summarized. The experiments were performed with the CBELSA/TAPS detector at the electron accelerator ELSA in Bonn using the $\eta\to3\pi^{0}\to6\gamma$ decay. A liquid deuterium target was used for the measurement of total cross sections and angular distributions. The results confirm earlier measurements from Bonn and the MAMI facility in Mainz about the existence of a narrow structure in the excitation function of $\gamma n\rightarrow n\eta$. The current angular distributions show a forward-backward asymmetry, which was previously not seen, but was predicted by model calculations including an additional narrow $P_{11}$ state. Furthermore, data obtained with a longitudinally polarized, deuterated butanol target and a circularly polarized photon beam were analyzed to determine the double polarization observable $E$. Both data sets together were also used to extract the helicity dependent cross sections $\sigma_{1/2}$ and $\sigma_{3/2}$. The narrow structure in the excitation function of $\gamma n\rightarrow n\eta$ appears associated with the helicity-1/2 component of the reaction.
Published: 2017
Full Text: View/download PDF

20. Measurement of polarisation observables inKs0Σ+photoproduction off the proton

Author: Volker Metag, H. Dutz, S. Schadmand, T. Mertens, T. C. Jude, Matthew Lang, H. Schmieden, R. Ewald, D. E. Bayadilov, K. Fornet-Ponse, A. B. Gridnev, Mariana Nanova, D. Walther, A. Suele, V. Sokhoyan, Friedrich Klein, J. G. Messchendorp, V. Kleber, T. Szczepanek, M. Ostrick, Herbert Löhner, A. Roy, I. Jaegle, K.-T. Brinkmann, I. V. Lopatin, Ch. Schmidt, R. Varma, V. Crede, E. Gutz, D. Trnka, O. Jahn, R. Beck, Wolfgang Hillert, Lalit Mohan Pant, B. Bantes, S. Kammer, Ch. Funke, D. Elsner, Yu. A. Beloglazov, A. V. Sarantsev, V. A. Nikonov, R. W. Novotny, A. V. Anisovich, Ph. Hoffmeister, B. Schoch, D. Menze, Eberhard Klempt, J. Hannappel, Ch. Wendel, V. V. Sumachev, U. Thoma, J. Junkersfeld, S. Shende, H. Kalinowsky, D. V. Novinski, H. van Pee, B. Krusche, O. Bartholomy, Frank Klein, and Frank Frommberger
Subjects: Physics, Nuclear physics, Nuclear and High Energy Physics, Photon, Proton, Partial wave analysis, Hyperon, Bremsstrahlung, Photon energy, Nuclear Experiment, Nucleon, 7. Clean energy, Sigma baryon
Abstract: The reaction γ p → K S 0 Σ + is studied in the photon energy range from threshold. Linearly polarised photon beams from coherent bremsstrahlung enabled the first measurement of photon beam asymmetries in this reaction up to E γ = 1650 MeV . In addition, the recoil hyperon polarisation was determined through the asymmetry in the weak decay Σ + → p π 0 up to E γ = 2250 MeV . The data are compared to partial wave analyses, and the possible impact on the interpretation of a recently observed prominent structure in the cross section near the K ⁎ thresholds is discussed.
Published: 2014
Full Text: View/download PDF

21. Experimental constraints on the ω–nucleus real potential

Author: D. Elsner, Frank Frommberger, Ph. Hoffmeister, Matthew Lang, V. Kleber, R. Schmitz, T. Seifen, Yu. A. Beloglazov, Wolfgang Hillert, Jens Hartmann, D. Piontek, I. V. Lopatin, T. Rostomyan, V. Metag, A. Wilson, B. Krusche, J. Hannappel, M. Gottschall, R. Ewald, K. Makonyi, H. Schmieden, D. E. Bayadilov, D. Kaiser, I. Jaegle, U. Wiedner, K.-T. Brinkmann, H. van Pee, A. Thiel, E. Gutz, Yasser Maghrbi, A. B. Gridnev, Mariana Nanova, D. Walther, U. Thoma, M. Grüner, Ch. Honisch, Ch. Hammann, Ch. Schmidt, J. Müller, K. Fornet-Ponse, Friedemann Zenke, V. Crede, S. Friedrich, P. Drexler, S. Kammer, A. Winnebeck, Steffen Schaepe, F. Dietz, H. Eberhardt, Ch. Wendel, Th. Challand, Ch. Funke, Janus Weil, I. Keshelashvili, D. Hammann, Satoru Hirenzaki, T. Odenthal, T. Dahlke, Hideko Nagahiro, Friedrich Klein, B. Bantes, S. Böse, H. Kalinowsky, and R. Beck
Subjects: Physics, education.field_of_study, Nuclear and High Energy Physics, Meson, Hadron, Population, Nuclear Theory, Carbon-12, Elementary particle, lcsh:QC1-999, Pion, Bound state, Atomic physics, Nucleon, education, Nuclear Experiment, lcsh:Physics
Abstract: In a search for $\omega$ mesic states, the production of $\omega$-mesons in coincidence with forward going protons has been studied in photon induced reactions on $^{12}$C for incident photon energies of 1250 - 3100 MeV. The $\pi^0 \gamma$ pairs from decays of bound or quasi-free $\omega$-mesons have been measured with the CBELSA/TAPS detector system in coincidence with protons registered in the MiniTAPS forward array. Structures in the total energy distribution of the $\pi^0 \gamma$ pairs, which would indicate the population and decay of bound $\omega~^{11}$B states, are not observed. The $\pi^0 \gamma$ cross section of 0.3 nb/MeV/sr observed in the bound state energy regime between -100 and 0 MeV may be accounted for by yield leaking into the bound state regime because of the large in-medium width of the $\omega$-meson. A comparison of the measured total energy distribution with calculations suggests the real part $V_0$ of the $\omega~^{11}$B potential to be small and only weakly attractive with $V_0(\rho=\rho_0) = -15\pm$ 35(stat) $\pm$20(syst) MeV in contrast to some theoretical predictions of attractive potentials with a depth of 100 - 150 MeV., Comment: 13 pages, 8 figures
Published: 2014
Full Text: View/download PDF

22. Determination of the eta '-nucleus optical potential

Author: Ch. Hammann, Friedemann Zenke, Ch. Honisch, Ch. Schmidt, R. Ewald, P. Drexler, A. Winnebeck, Yasser Maghrbi, E. Ya. Paryev, J. Müller, R. Beck, H. Eberhardt, Jens Hartmann, S. Friedrich, T. Seifen, I. Keshelashvili, Friedrich Klein, D. Walther, U. Thoma, A. Thiel, T. Dahlke, H. Schmieden, Matthew Lang, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, V. Metag, V. Kleber, Ch. Wendel, I. Jaegle, Eberhard Klempt, K.-T. Brinkmann, Wolfgang Hillert, D. Kaiser, J. Hannappel, Yu. A. Beloglazov, D. Piontek, D. Elsner, I. V. Lopatin, Ph. Hoffmeister, S. Böse, B. Krusche, H. Kalinowsky, S. Kammer, F. Dietz, Th. Challand, Ch. Funke, U. Wiedner, K. Fornet-Ponse, T. Odenthal, D. Hammann, K. Makonyi, H. van Pee, Steffen Schaepe, A. Wilson, Frank Frommberger, M. Grüner, V. Crede, M. Gottschall, E. Gutz, B. Bantes, and R. Schmitz
Subjects: Physics, Excitation function, Nuclear and High Energy Physics, Photon, Meson, 010308 nuclear & particles physics, Hadron, Nuclear Theory, Elementary particle, Electron, Nuclear matter, 01 natural sciences, 0103 physical sciences, Bound state, High Energy Physics::Experiment, Atomic physics, 010306 general physics, Nuclear Experiment
Abstract: The excitation function and momentum distribution of $\eta^\prime$ mesons have been measured in photon induced reactions on $^{12}{}$C in the energy range of 1250-2600 MeV. The experiment was performed with tagged photon beams from the ELSA electron accelerator using the Crystal Barrel and TAPS detectors. The data are compared to model calculations to extract information on the sign and magnitude of the real part of the $\eta^\prime$-nucleus potential. Within the model, the comparison indicates an attractive potential of -($37 \pm 10(stat)\pm10(syst)$) MeV depth at normal nuclear matter density. Since the modulus of this depth is larger than the modulus of the imaginary part of the $\eta^\prime$-nucleus potential of -($10\pm2.5$) MeV, determined by transparency ratio measurements, a search for resolved $\eta^\prime$-bound states appears promising., Comment: 13 pages, 6 figures
Published: 2013

23. Momentum dependence of the imaginary part of the $\omega$- and $\eta^\prime$-nucleus optical potential

Author: K. Makonyi, J. Hannappel, Ch. Funke, B. Krusche, H. van Pee, Ulrich Wiedner, Volker Metag, H. Eberhardt, T. Seifen, R. Schmitz, F. Kalischewski, Matthew Lang, T. Triffterer, Y. Wunderlich, E. Gutz, I. Keshelashvili, V. Crede, C. Sowa, Lilian Witthauer, D. Schaab, K. Koop, Friedrich Klein, Suvadeep Bose, F. Afzal, Reinhard Beck, D. Elsner, Ph. Hoffmeister, H. Schmieden, D. E. Bayadilov, D. Kaiser, M. Urban, Mariana Nanova, Ch. Wendel, Wolfgang Hillert, Frank Frommberger, M. Gottschall, V. Sokhoyan, U. Thoma, D. Werthmüller, M. Grüner, B. Bantes, Alastair J. Wilson, T. C. Jude, Jens Hartmann, Matthew L. Becker, D. Piontek, H. G. Zaunick, K. Spieker, D. Walther, J. Müller, A. Thiel, Ch. Hammann, P. Drexler, J. Müllers, Ch. Honisch, Ch. Schmidt, S. Friedrich, Francesco Messi, K.-T. Brinkmann, and T. Rostomyan
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Photon, Meson, 010308 nuclear & particles physics, High Energy Physics::Phenomenology, Nuclear Theory, 01 natural sciences, Omega, Momentum, 0103 physical sciences, Bound state, Production (computer science), ddc:530, High Energy Physics::Experiment, Absorption (logic), 010306 general physics, Nuclear Experiment, Glauber
Abstract: The photoproduction of $\omega$ and $\eta^\prime$ mesons off carbon and niobium nuclei has been measured as a function of the meson momentum for incident photon energies of 1.2-2.9 GeV at the electron accelerator ELSA. The mesons have been identified via the $\omega \rightarrow \pi^0 \gamma \rightarrow 3 \gamma$ and $\eta^\prime\rightarrow \pi^0 \pi^0\eta \rightarrow 6 \gamma$ decays, respectively, registered with the CBELSA/TAPS detector system. From the measured meson momentum distributions the momentum dependence of the transparency ratio has been determined for both mesons. Within a Glauber analysis the in-medium $\omega$ and $\eta^\prime$ widths and the corresponding absorption cross sections have been deduced as a function of the meson momentum. The results are compared to recent theoretical predictions for the in-medium $\omega$ width and $\eta^\prime$-N absorption cross sections. The energy dependence of the imaginary part of the $\omega$- and $\eta^\prime$-nucleus optical potential has been extracted. The finer binning of the present data compared to the existing data allows a more reliable extrapolation towards the production threshold. The modulus of the imaginary part of the $\eta^\prime$ nucleus potential is found to be about three times smaller than recently determined values of the real part of the $\eta^\prime$-nucleus potential, which makes the $\eta^\prime$ meson a suitable candidate for the search for meson-nucleus bound states. For the $\omega$ meson, the modulus of the imaginary part near threshold is comparable to the modulus of the real part of the potential. As a consequence, only broad structures can be expected which makes the observation of $\omega$ mesic states very difficult experimentally., Comment: 10 pages, 8 figures
Published: 2016
Full Text: View/download PDF

24. Determination of the real part of the η ′ -Nb optical potential

Author: J. Müllers, Y. Wunderlich, Matthew Lang, J. Hannappel, Alastair J. Wilson, T. C. Jude, M. Becker, Ulrich Wiedner, U. Thoma, R. Schmitz, T. Triffterer, E. Gutz, D. Elsner, V. Crede, V. Metag, Ph. Hoffmeister, Suvadeep Bose, Christian Schmidt, A. Thiel, K. Spieker, B. Krusche, Friedrich Klein, Ch. Hammann, T. Rostomyan, K.-T. Brinkmann, Wolfgang Hillert, D. Walther, K. Koop, M. Urban, D. Schaab, E. Ya. Paryev, D. Piontek, Jörg H. Müller, Jens Hartmann, F. Afzal, H. Schmieden, D. E. Bayadilov, Mariana Nanova, K. Makonyi, H. van Pee, Hans-Georg Zaunick, S. Friedrich, Lilian Witthauer, Francesco Messi, Ch. Honisch, F. Kalischewski, Reinhard Beck, Frank Frommberger, Ch. Wendel, C. Sowa, D. Werthmüller, M. Grüner, I. Keshelashvili, and T. Seifen
Subjects: Excitation function, Physics, Meson, 010308 nuclear & particles physics, Nuclear Theory, Bremsstrahlung, Particle accelerator, Nuclear matter, 01 natural sciences, law.invention, Nuclear physics, Momentum, law, Excited state, 0103 physical sciences, Bound state, High Energy Physics::Experiment, ddc:530, Atomic physics, 010306 general physics, Nuclear Experiment
Abstract: The excitation function and momentum distribution of {\eta}' mesons have been measured in photoproduction off 93^Nb in the energy range of 1.2-2.9 GeV. The experiment has been performed with the combined Crystal Barrel and MiniTAPS detector system, using tagged photon beams from the ELSA electron accelerator. Information on the sign and magnitude of the real part of the {\eta}'-Nb potential has been extracted from a comparison of the data with model calculations. An attractive potential of -(41 \pm 10(stat) \pm 15(syst)) MeV depth at normal nuclear matter density is deduced within model uncertainties. This value is consistent with the potential depth of -(37 \pm 10(stat) \pm 10(syst)) MeV obtained in an earlier measurement for a light nucleus (carbon). This relatively shallow {\eta}'-nucleus potential will make the search for {\eta}'-nucleus bound states more difficult., Comment: 9 pages, 6 figures
Published: 2016
Full Text: View/download PDF

25. Double-polarization observable G in neutral-pion photoproduction off the proton

Author: U. Thoma, V. Crede, F. Afzal, Reinhard Beck, D. Elsner, P. Klassen, H. Dutz, K.-T. Brinkmann, S. Kammer, S. Runkel, H. Eberhardt, D. Walther, I. Keshelashvili, Ch. Honisch, Ch. Hammann, K. Fornet-Ponse, Ch. Schmidt, Ch. Funke, B. Krusche, Ch. Wendel, M. Grüner, E. Gutz, Jens Hartmann, S. Böse, A. Winnebeck, G. Reicherz, A. V. Anisovich, P. Mahlberg, H. Kalinowsky, K. Spieker, M. Bichow, Friedrich Klein, S. Friedrich, J. Müllers, Eberhard Klempt, Volker Metag, A. V. Sarantsev, Matthew Lang, W. Meyer, St. Goertz, M. Urban, Frank Frommberger, D. Kaiser, M. Dieterle, V. A. Nikonov, F. Kalischewski, B. Bantes, V. Sokhoyan, K. Koop, R. Ewald, H. Schmieden, D. E. Bayadilov, A. Thiel, A. B. Gridnev, Mariana Nanova, M. Kube, M. Gottschall, Wolfgang Hillert, J. Hannappel, Ph. Hoffmeister, V. Kleber, T. Seifen, Alastair J. Wilson, T. C. Jude, D. Piontek, I. V. Lopatin, Lilian Witthauer, D. Hammann, K. Makonyi, S. Reeve, H. van Pee, and J. Müller
Subjects: Physics, Nuclear and High Energy Physics, Photon, Proton, 010308 nuclear & particles physics, Nuclear Theory, Bremsstrahlung, Diamond, FOS: Physical sciences, Observable, Photon energy, engineering.material, Polarization (waves), 01 natural sciences, Nuclear physics, Pion, 0103 physical sciences, engineering, ddc:530, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment
Abstract: This paper reports on a measurement of the double-polarization observable G in $\pi^0$ photoproduction off the proton using the CBELSA/TAPS experiment at the ELSA accelerator in Bonn. The observable G is determined from reactions of linearly-polarized photons with longitudinally-polarized protons. The polarized photons are produced by bremsstrahlung off a properly oriented diamond radiator. A frozen spin butanol target provides the polarized protons. The data cover the photon energy range from 617 to 1325 MeV and a wide angular range. The experimental results for G are compared to predictions by the Bonn-Gatchina (BnGa), J\"ulich-Bonn (J\"uBo), MAID and SAID partial wave analyses. Implications of the new data for the pion photoproduction multipoles are discussed.
Published: 2016
Full Text: View/download PDF

26. Anomaly in the KS0Σ+ photoproduction cross section off the proton at the K⁎ threshold

Author: Volker Metag, Wolfgang Hillert, S. Shende, A. Suele, D. Walther, S. Kammer, Ch. Funke, Frank Frommberger, J. Hannappel, H. van Pee, D. Elsner, B. Krusche, D. Menze, R. W. Novotny, Ph. Hoffmeister, O. Bartholomy, B. Schoch, H. Schmieden, U. Thoma, D. E. Bayadilov, A. B. Gridnev, E. Gutz, A. Roy, Mariana Nanova, T. Szczepanek, V. Sokhoyan, Eberhard Klempt, Yu. A. Beloglazov, Ch. Wendel, R. Beck, V. V. Sumachev, Frank Klein, J. Junkersfeld, K. T Brinkmann, H. Kalinowsky, Matthew Lang, S. Schadmand, M. Ostrick, V. Kleber, R. Varma, L. M. Pant, H. Dutz, V. Crede, T. Mertens, Herbert Löhner, R. Ewald, B. Bantes, D. V. Novinski, D. Trnka, Ch. Schmidt, O. Jahn, K. Fornet-Ponse, I. Jaegle, Friedrich Klein, I. V. Lopatin, T. C. Jude, and J. G. Messchendorp
Subjects: Physics, Nuclear physics, Baryon, Nuclear and High Energy Physics, Cross section (physics), Proton, Meson, Hadron, Elementary particle, Strangeness, Nucleon
Abstract: The γ + p → K 0 + Σ + photoproduction reaction is investigated in the energy region from threshold to E γ = 2250 MeV . The differential cross section exhibits increasing forward-peaking with energy, but only up to the K ⁎ threshold. Beyond, it suddenly returns to a flat distribution with the forward cross section dropping by a factor of four. In the total cross section a pronounced structure is observed between the K ⁎ Λ and K ⁎ Σ thresholds.
Published: 2012
Full Text: View/download PDF

27. Transparency ratio in γA→η′A′ and the in-medium η′ width

Author: B. Krusche, I. Horn, V. Metag, A. Radkov, S. Lugert, O. Bartholomy, D. Menze, Angels Ramos, Eberhard Klempt, S. Höffgen, K.-T. Brinkmann, T. Szczepanek, Ch. Wendel, I. Jaegle, A. Süle, V. V. Sumachev, J. Junkersfeld, K. Essig, C. Morales, M. Fuchs, H. Dutz, Frank Klein, Yu. A. Beloglazov, A. Ehmanns, E. Gutz, Ch. Funke, M. Konrad, Lalit Mohan Pant, M. Ostrick, H. Kalinowsky, M. Pfeiffer, Friedrich Klein, K. Makonyi, R. Ewald, I. V. Lopatin, T. Mertens, Herbert Löhner, H. van Pee, V. Crede, B. Kopf, D. Trnka, J. Langheinrich, J. G. Messchendorp, D. Elsner, U. Thoma, Ankhi Roy, R. W. Novotny, J. Lotz, D. Walther, Ph. Hoffmeister, B. Schoch, Ch. Schmidt, Eulogi Oset, H. Schmieden, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, I. Fabry, S. Schadmand, R. Gregor, and R. Varma
Subjects: Physics, Nuclear and High Energy Physics, Photon, Proton, Meson, 010308 nuclear & particles physics, Scattering, Nuclear Theory, Niobium, chemistry.chemical_element, Rest frame, 7. Clean energy, 01 natural sciences, Momentum, Nuclear physics, Cross section (physics), chemistry, 0103 physical sciences, High Energy Physics::Experiment, Atomic physics, Nuclear Experiment, 010306 general physics
Abstract: The photoproduction of η ′ -mesons off different nuclei has been measured with the CBELSA/TAPS detector system for incident photon energies between 1500–2200 MeV. The transparency ratio has been deduced and compared to theoretical calculations describing the propagation of η ′ -mesons in nuclei. The comparison indicates a width of the η ′ -meson of the order of Γ = 15 – 25 MeV at ρ = ρ 0 for an average momentum p η ′ = 1050 MeV / c , at which the η ′ -meson is produced in the nuclear rest frame. The inelastic η ′ N cross section is estimated to be 3–10 mb. Parameterizing the photoproduction cross section of η ′ -mesons by σ ( A ) = σ 0 A α , a value of α = 0.84 ± 0.03 has been deduced.
Published: 2012
Full Text: View/download PDF

28. Photoproduction of meson pairs: First measurement of the polarization observable Is

Author: Matthew Lang, T. Mertens, Herbert Löhner, A. Suele, Michael Fuchs, V. Crede, D. Piontek, D. Walther, M. Pfeiffer, I. V. Lopatin, A. Thiel, V. Metag, Ch. Schmidt, H. Dutz, V. Sokhoyan, J. G. Messchendorp, M. Kotulla, J. C. S. Bacelar, Friedrich Klein, R. Beck, I. Jaegle, Winston Roberts, M. Ostrick, R. Gregor, R. Ewald, R. Castelijns, S. Schadmand, Ch. Weinheimer, H. Schmieden, R. Varma, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, D. Trnka, D. Elsner, T. Szczepanek, V. Kleber, R. W. Novotny, Ph. Hoffmeister, S. Kammer, B. Schoch, Ch. Funke, Lalit Mohan Pant, S. Lugert, Wolfgang Hillert, Eberhard Klempt, Ankhi Roy, V. A. Nikonov, D. Menze, I. Horn, A. V. Anisovich, Ch. Wendel, B. Bantes, V. V. Sumachev, Yu. A. Beloglazov, A. V. Sarantsev, H. Kalinowsky, B. Krusche, E. Gutz, D. V. Novinski, S. Shende, U. Thoma, H. van Pee, O. Bartholomy, J. Junkersfeld, Frank Frommberger, and Frank Klein
Subjects: Physics, Nuclear and High Energy Physics, Photon, Meson, Proton, Linear polarization, media_common.quotation_subject, Partial wave analysis, FOS: Physical sciences, Observable, Polarization (waves), Asymmetry, Nuclear physics, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment, media_common
Abstract: The polarization observable I^s, a feature exclusive to the acoplanar kinematics of multi-meson final states produced via linearly polarized photons, has been measured for the first time. Results for the reaction g p -> p pi0 eta are presented for incoming photon energies between 970 MeV and 1650 MeV along with the beam asymmetry I^c. The comparably large asymmetries demonstrate a high sensitivity of I^s to the dynamics of the reaction. Fits using Bonn-Gatchina partial wave analysis demonstrate that the new polarization observables carry significant information on the contributing partial waves., 11 pages, 6 figures, v2 to appear in Phys. Lett. B
Published: 2010
Full Text: View/download PDF

29. Erratum to: High-statistics study of the reaction $\gamma p\rightarrow p2\pi^{0}$

Author: V. Metag, S. Lugert, Eberhard Klempt, T. Seifen, M. Kotulla, Alastair J. Wilson, Frank Klein, M. Ostrick, D. Walther, S. Kammer, Friedrich Klein, T. Mertens, H. Dutz, V. A. Nikonov, Ch. Funke, Herbert Löhner, J. G. Messchendorp, Lalit Mohan Pant, V. Crede, I. Horn, Frank Frommberger, S. Shende, A. Thiel, Ankhi Roy, Ch. Schmidt, V. Sokhoyan, R. Ewald, B. Krusche, H. Pee, O. Bartholomy, M. Pfeiffer, T. Szczepanek, E. Gutz, B. Bantes, H. Kalinowsky, Michael Fuchs, Yu. A. Beloglazov, D. Piontek, J. C. S. Bacelar, A. V. Sarantsev, B. Metsch, D. Trnka, I. V. Lopatin, Ch. Wendel, Matthew Lang, V. V. Sumachev, A. V. Anisovich, I. Jaegle, V. Kleber, R. Gregor, R. Varma, J. Junkersfeld, D. Elsner, R. W. Novotny, Ph. Hoffmeister, U. Thoma, R. Castelijns, H. Schmieden, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, A. Süle, Wolfgang Hillert, D. Novinsky, and R. Beck
Subjects: Physics, Baryon, Nuclear and High Energy Physics, Meson, Isospin, Partial wave analysis, Bremsstrahlung, Dalitz plot, Photon energy, Atomic physics, Nucleon
Abstract: The photoproduction of 2π$^{0}$ mesons off protons was studied with the Crystal Barrel/TAPS experiment at the electron accelerator ELSA in Bonn. The energy of photons produced in a radiator was tagged in the energy range from 600 MeV to 2.5 GeV. Differential and total cross sections and pπ$^{0}$ π$^{0}$ Dalitz plots are presented. Part of the data was taken with a diamond radiator producing linearly polarized photons, and beam asymmetries were derived. Properties of nucleon and Δ resonances contributing to the pπ$^{0}$ π$^{0}$ final state were determined within the Bonn-Gatchina (BnGa) partial-wave analysis. The data presented here allow us to determine branching ratios of nucleon and Δ resonances for their decays into pπ$^{0}$ π$^{0}$ via several intermediate states. Most prominent are decays proceeding via Δ(1232)π, N(1440)1/2$^{+}$ π, N(1520)3/2$^{−}$ π, N(1680)5/2$^{+}$ π, but also pf$_{0}$(500), pf$_{0}$(980), and pf$_{2}$(1270) contribute to the reaction.
Published: 2015
Full Text: View/download PDF

30. High-statistics study of the reaction γp → p2π0

Author: S. Kammer, Ch. Funke, M. Kotulla, V. Crede, T. Szczepanek, E. Gutz, Alastair J. Wilson, H. Schmieden, Yu. A. Beloglazov, J. C. S. Bacelar, A. V. Sarantsev, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, Frank Frommberger, V. Sokhoyan, V. Metag, H. Kalinowsky, H. Dutz, A. V. Anisovich, J. G. Messchendorp, U. Thoma, O. Bartholomy, Friedrich Klein, V. A. Nikonov, M. Pfeiffer, Lalit Mohan Pant, M. Ostrick, J. Junkersfeld, T. Seifen, I. Horn, S. Lugert, Ch. Schmidt, Ch. Wendel, V. V. Sumachev, Eberhard Klempt, T. Mertens, Frank Klein, Herbert Löhner, Michael Fuchs, A. Thiel, D. Piontek, B. Metsch, Ankhi Roy, I. V. Lopatin, H. van Pee, B. Krusche, S. Shende, B. Bantes, Wolfgang Hillert, D. Elsner, R. W. Novotny, Ph. Hoffmeister, I. Jaegle, D. Walther, R. Ewald, R. Varma, V. Kleber, Matthew Lang, R. Gregor, D. Novinsky, R. Beck, D. Trnka, R. Castelijns, and A. Süle
Subjects: Nuclear physics, Physics, Nuclear and High Energy Physics, Range (particle radiation), Photon, Meson, law, Linear polarization, Partial wave analysis, Particle accelerator, Nucleon, Beam (structure), law.invention
Abstract: The photoproduction of 2$\pi^0$ mesons off protons was studied with the Crystal Barrel/TAPS experiment at the electron accelerator ELSA in Bonn. The energy of photons produced in a radiator was tagged in the energy range from 600\,MeV to 2.5\,GeV. Differential and total cross sections and $p\pi^0\pi^0$ Dalitz plots are presented. Part of the data was taken with a diamond radiator producing linearly polarized photons, and beam asymmetries were derived. Properties of nucleon and $\Delta$ resonances contributing to the $p\pi^0\pi^0$ final state were determined within the BnGa partial wave analysis. The data presented here allow us to determine branching ratios of nucleon and $\Delta$ resonances for their decays into $p\pi^0\pi^0$ via several intermediate states. Most prominent are decays proceeding via $\Delta(1232)\pi$, $N(1440)1/2^+\pi$, $N(1520)3/2^-\pi$, $N(1680)5/2^+\pi$, but also $pf_0(500)$, $pf_0(980)$, and $pf_2(1270)$ contribute to the reaction.
Published: 2015
Full Text: View/download PDF

31. Three-Body Nature ofNandΔResonances from Sequential Decay Chains

Author: Frank Klein, V. Sokhoyan, A. Wilson, E. Gutz, M. Pfeiffer, S. Shende, J. Junkersfeld, J. G. Messchendorp, R. Beck, D. V. Novinski, Ch. Schmidt, M. Kotulla, D. Walther, V. A. Nikonov, R. Castelijns, Matthew Lang, Wolfgang Hillert, A. Thiel, A. V. Anisovich, I. Horn, S. Lugert, H. Kalinowsky, Cbelsa, U. Thoma, Eberhard Klempt, B. Bantes, V. Kleber, D. Elsner, Volker Metag, H. van Pee, R. Gregor, R. Varma, T. Mertens, Friedrich Klein, Herbert Löhner, R. W. Novotny, Yu. A. Beloglazov, B. Krusche, A. Roy, A. V. Sarantsev, Ph. Hoffmeister, O. Bartholomy, L. M. Pant, H. Dutz, S. Kammer, Bernard Metsch, Frank Frommberger, D. Piontek, Ch. Wendel, Ch. Funke, I. V. Lopatin, V. V. Sumachev, H. Schmieden, V. Crede, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, A. Süle, I. Jaegle, M. Ostrick, D. Trnka, J. C. S. Bacelar, R. Ewald, T. Szczepanek, and M. Fuchs
Subjects: Physics, Partial wave analysis, Nuclear Theory, General Physics and Astronomy, Dalitz plot, Delta baryon, Particle decay, Pion, Isobar, High Energy Physics::Experiment, Decay chain, Atomic physics, Nuclear Experiment, Nucleon
Abstract: The N pi(0)pi(0) decays of positive-parity N* and Delta* resonances at about 2 GeV are studied at ELSA by photoproduction of two neutral pions off protons. The data reveal clear evidence for several intermediate resonances: Delta(1232), N(1520)3/2(-), and N(1680)5/2(+), with spin parities J(P) = 3/2(+), 3/2(-), and 5/2(+). The partial wave analysis (within the Bonn-Gatchina approach) identifies N(1440)1/2(+) and the N(pi pi)s (wave) (abbreviated as N sigma here) as further isobars and assigns the final states to the formation of nucleon and Delta resonances and to nonresonant contributions. We observe the know Delta(1232)pi decays of Delta(1910)1/2(+), Delta(1920)3/2(+), Delta(1905)5/2(+), Delta(1950)7/2(+), and of the corresponding spin-parity series in the nucleon sector, N(1880)1/2(+), N(1900)3/2(+), N(2000)5/2(+), and N(1990)7/2(+). For the nucleon resonances, these decay modes are reported here for the first time. Further new decay modes proceed via N(1440)1/2(pi)(+), N(1520)3/2(pi)(-) , N(1680)5/2(pi)(+), and N sigma. The latter decay modes are observed in the decay of N* resonances and at most weakly in Delta(*) decays. It is argued that these decay modes provide evidence for a 3-quark nature of N* resonances rather than a quark-diquark structure.
Published: 2015
Full Text: View/download PDF

32. Photoproduction of omega mesons off protons and neutrons

Author: A. Süle, S. Höffgren, O. Bartholomy, M. Kotulla, Ankhi Roy, M. Konrad, Friedrich Klein, M. Ostrick, S. Schadmand, Matthew Lang, H. Dutz, M. Pfeiffer, J. C. S. Bacelar, V. Kleber, S. Shende, J. Junkersfeld, H. Schmieden, D. E. Bayadilov, V. Crede, H. Kalinowsky, R. Ewald, A. B. Gridnev, Mariana Nanova, I. Jaegle, A. V. Anisovich, Ch. Schmidt, T. Szczepanek, D. Menze, H. van Pee, S. Kammer, Frank Klein, R. Varma, F. Dietz, A. Wilson, I. V. Lopatin, T. Mertens, Herbert Löhner, U. Thoma, V. Shklyar, Ch. Wendel, Lalit Mohan Pant, Frank Frommberger, C. Funke, R. Beck, D. Walter, V. V. Sumachev, J. G. Messchendorp, R. W. Gothe, R. Castelijns, R. Gregor, D. Trnka, E. Gutz, V. Metag, B. Bantes, T. Rostomyan, V. A. Nikonov, I. Horn, S. Lugert, Eberhard Klempt, Y. A. Belogazov, D. Elsner, R. W. Novotny, Ph. Hoffmeister, B. Schoch, Wolfgang Hillert, B. Krusche, D. V. Novinski, and Research unit Nuclear & Hadron Physics
Subjects: Nuclear reaction, Physics, TAPS, Nuclear and High Energy Physics, Proton, Meson, Astrophysics::High Energy Astrophysical Phenomena, Hadron, Nuclear Theory, WIDTH, Photon energy, DEUTERON, Nuclear physics, Deuterium, NUCLEAR MEDIUM, Neutron, High Energy Physics::Experiment, PHI-PHOTOPRODUCTION, SPECTROMETER, Atomic physics, Nucleon, Nuclear Experiment, MATTER
Abstract: Omega photoproduction off hydrogen and deuterium has been studied with the tagged photon beam of the ELSA accelerator in Bonn for photon energies up to 2.0 GeV. The omega meson has been identified via the omega -> pi(0) gamma -> gamma gamma gamma decay mode, using the combined setup of the Crystal Barrel/TAPS detector systems. Both inclusive and exclusive analyses have been carried out. Differential and total cross-sections have been derived for omega mesons produced off free protons and off protons and neutrons bound in deuterium. The cross-section for the production off the bound neutron is found to be a factor of a parts per thousand 1.3 larger than the one off the bound proton in the incident beam energy region 1.2 GeV
Published: 2015
Full Text: View/download PDF

33. Experimental access to Transition Distribution Amplitudes with the P̄ANDA experiment at FAIR

Author: M. C. Mora Espí, Pawel Marciniewski, K. Makonyi, Yupeng Yan, S. Wronka, D. Pietreanu, Shaji Kumar, N. Belikov, D. I. Glazier, A. Gillitzer, K. Khanchai, Ajay Kumar Rai, M. Steinen, D. Calvo, Yury Tikhonov, A. A. Derevschikov, T. A. Pocheptsov, R.A. Salmin, P. Balanutsa, B. J. Liu, P. N. Deepak, A. E. Blinov, S. Lange, S. Ryzhikov, G. Kalicy, Arpit Parmar, P. Musiol, G. D. Alexeev, D. P. Watts, Lennart Isaksson, Tobias Stockmanns, E. Gutz, P. F. Dalpiaz, Zhi Liu, D. Marchand, S. Grieser, A. Gerhardt, D. Kangh, L. Fava, A. A. Festchenko, Harphool Kumawat, I. Zimmermann, M. Albrecht, B. Krusche, A. Sanchez Lorente, E. A. Strokovsky, M. A. Pasyuk, J. Ritman, P. C. Vinodkumar, T. Quagli, M.G. Sapozhnikov, Ashok Kumar, Herbert Koch, V. I. Astakhov, V. Serdyuk, K. M. von Würtemberg, D. Münchow, Hans-Georg Zaunick, S. Marcello, M. Ullrich, A. Mustafa, Paola Gianotti, T. Kuske, Michaela Thiel, Kamal K. Seth, S. Schlimme, C. Schwarz, M. Savrie, B. Ketzer, Jerzy Smyrski, E. Etzelmüller, A. G. Fedunov, H. Sohlbach, K. Malgorzata, Victor Bobrovnikov, R.Sh. Teshev, L. Ayut, V.M. Abazov, B. Spruck, B. Kamys, D. Mülhheim, Krzysztof Swientek, S. Schadmand, M. V. Korzihik, Zbigniew Rudy, Matei Eugen Vasile, T. Wasem, J. Schwiening, D. Lehmann, M. Patsyuk, Karin Schönning, W. Czyzycki, M. Zühlsdorf, V. N. Goryachev, A. G. Zorin, A. Davidenko, W. Lauth, B. Fröhlich, A. Amoroso, V. Lucherini, P. Schakel, Grzegorz Korcyl, G.A. Mustafaev, Smbat Grigoryan, Ajit Kumar Mohanty, Grzegorz Filo, R. Veenstra, P. Wüstner, J. Marton, Boris Batyunya, L. Ferrero, A. N. Skachkova, Edward Lisowski, I. Garzia, D. Bremer, T. Eissner, D. Lin, Y.M. Goncharenko, Soumen Paul, A.A. Efremov, Dipanwita Dutta, Alberto Rotondi, M. Michel, B. Slowinski, A. Arefiev, Philip Woods, I. Augustin, Yan Liang, A. Karavdina, M. Greco, P. Rosier, Antoni Szczurek, N. Saito, K. Föhl, T. Schröder, B. Singh, Mariana Nanova, Andreas Herten, Oleg V. Missevitch, S.A. Zaporozhets, K.-T. Brinkmann, Sukanta Dash, A. Filippi, A. Trzcinski, Marek Idzik, M. O. Distler, J. Schumann, C. Sowa, I. Konorov, J. C. van der Weele, Mathias Fink, A. E. Yakutin, B. Kopf, E. Atomssa, A. Pitka, R. Karabowicz, H. H. Leithoff, Angelo Rivetti, S. Pornrad, S. Diehl, M. Maggiora, B. Kröck, R. Duchat, O. Levitskaya, Gianluigi Boca, Krzysztof Korcyl, Gianangelo Bracco, Harald Kleines, F. Nerling, L. Caldeira Balkeståhl, S. Coli, E. Perevalova, T. Gessler, Klaus Peters, A. Magiera, Vassili Kachanov, M. Hawryluk, S. Ong, R. Varma, X. Shen, T. Czyzewski, M. Domagala, S. Godre, M. Zyzak, J. Pettersson, F. Uhlig, F. De Mori, P.J.J. Lemmens, Alexander D. Vasiliev, Mohammed Al-Turany, Q. Hu, Andrzej Kupsc, R. Schmitz, P. Mahlberg, P. De Remigis, C. Schnier, S. Lusso, R. Dosdall, L. Zotti, J. Van de Wiele, A. Britting, S. Fissum, Zhigang Li, Jozef Zlomanczuk, Amiran Tomaradze, S. Spataro, U. Müller, R. Valente, V. Uzhinsky, Giulio Stancari, G. S. Shabratova, I. Keshelashvili, S. Jowzaee, Harald Merkel, C. Guaraldo, S. Li, Christian Schmidt, M. Steinacher, V. Kozlov, Yu.N. Rogov, A. Bianconi, T. Held, V. Datar, Andrei Fedorov, H. Orth, T. Weber, A. Kozela, Piotr Salabura, M. Destefanis, Andrea Lavagno, M. Kuhlmann, B. Ma, J. Pychy, Piotr Lebiedowicz, L. Capozza, Dominik Kwiatkowski, Andrew Levin, A. Wilms, Germán Mazza, Matthias Richter, Wojciech Krzemien, Sean A Dobbs, J. Pochodzalla, I. Shein, H. Ohm, Paolo Montagna, Paul Alois Buhler, Y. Naryshkin, Hans Calén, A. Apostolou, S. Orfanitski, V. Grishin, A. Kashchuk, V. Kormilitsin, Tomasz Fiutowski, M. Mingnore, M. Krebs, A. Dolgolenko, E. Fioravanti, P.-E. Tegnér, A. Chlopik, A. Gromliuk, Andreas Lehrach, I. Georgadze, B. Czech, B. Zwieglinski, Kurt Hansen, W. Schäfer, C. Motzko, R. Kunne, P. Genova, J. Lühning, A. Psyzniak, S. Bianco, H. Smit, Nicola Bianchi, Felice Iazzi, J. Rieke, M. Fritsch, R. Dzhygadlo, O. Corell, E. Pace, S. I. Manaenkov, V. Chandratre, S. Sosio, A. Olshevskiy, T. Johansson, S. Sanchez, Concettina Sfienti, R. F. Parodi, D. Walther, T. Saito, E. Köhler, Zhi Sun, Markus Büscher, P. Kulessa, Magnus Wolke, I. Kisel, V. Tokmenin, Alexander Vodopyanov, J.H. Zhao, C. Wang, M. Kube, M. Kavatsyuk, T. Hennino, Johann Zmeskal, V. Varentsov, C. Morales Morales, S. Esch, R. Kliemt, G. Schepers, S. Poslavskiy, Alessandro Drago, Dan Pantea, M. Imre, W. Eyrich, D. Melnychuk, M.P. Bussa, Dirk Grunwald, I. Lehmann, D. Rodríguez Piñeiro, Kjell Fransson, A. P. Onuchin, Valery Dormenev, M. Rossbach, F. E. Maas, Giuseppe Giraudo, M. Pelizäus, D. P. Mohanta, H. Deppe, C. Rosenbaum, M. Cardinali, A. G. Denig, A. Boukharov, V. Abramov, A. Hayrapetyan, K. Pysz, Vladimir Blinov, A. K. Hergemöller, A. Ryazantsev, K. Kalita, P. Wintz, Raghunath Sahoo, V. Akishina, P. A. Semenov, V. Balanutsa, Mikael Lundin, M. M. Macri, Anne-Laure Martin, A. Karmokov, U. Cahit, A. Demekhin, G. Rosner, W. Erni, S. Plueger, S. Leiber, Michael Werner, L. Schmitt, S. Costanza, Bent Schröder, R. Arora, D. Deermann, M. Leyhe, S.A. Kononov, S. Belostotski, Ulrich Wiedner, Maria Krawczyk, L. V. Malinina, M. Tiemens, Yu.M. Mel'nik, Ch. Schmidt, O. Merle, U. Thoma, M. Babai, A. Semenov, R. Maier, Ankhi Roy, Michael Düren, L. V. Nogach, E. Widmann, A. Zhadanov, Valentino Rigato, Stanisław Kistryn, P. Fedorets, K. Suzuki, D. A. Morozov, Franco Bradamante, Torbjörn Bäck, L. Busso, C. Le Galliard, Bhavin Patel, Alessandro Bressan, K. Chinorat, M. Wojciechowski, A. Lehmann, A.F. Makarov, A. Galoyan, P. Wieczorek, T. Holtmann, Bernd Voss, Aleksandra Wrońska, J. S. Díaz, M. Hoek, D. Veretennikov, F. H. Heinsius, P. Brandys, F. Balestra, H. Flemming, F. Lisowski, H. Younis, Paweł Moskal, G. Maniscalco, P. Jasinski, V. K. Rodionov, J. G. Messchendorp, R. Schnell, O. Miklukho, D. Prasuhn, M. Zambrana, M. Kümmel, L. Cao, I. Marishev, A. Bersani, Bo Cederwall, K. Götzen, L. Lavezzi, S. Vejdani, N. G. Minaev, Herbert Löhner, V. Metag, R. W. Novotny, E. Tomasi-Gustafsson, N. B. Skachkov, A. Cebulla, Bartosz Mindur, V. Chernetsky, B. Seitz, Daniel M. Kaplan, E. K. Koshurnikov, B. Ramstein, A. Kulkarni, B. J. Roy, T. Sefzick, D. Khaneft, D. Branford, A. A. Piskun, Reinhard Beck, S. Bleser, Yu. Yu. Lobanov, R. Siudak, V. I. Lobanov, E. A. Kravchenko, S. Bukreeva, A. Samartsev, U. Thöring, F. Feldbauer, Ting Xiao, Patrick Achenbach, Hongwei Liu, Johannes Peter Wessels, D. Bettoni, Yu.I. Davydov, V. I. Dormenev, Genady Gavrilov, Ch. Wendel, M. Yu. Barabanov, Kirill M. Semenov-Tian-Shansky, R. Birsa, T. Bel, Günter Kemmerling, A. Khoukaz, V. Carassiti, B. Galnander, Jifeng Hu, M. Bragadireanu, I. A. Kuyanov, Bruce Yabsley, Andrey V. Izotov, O. Noll, J. Kunkel, A. Dbeyssi, K. Suvorov, Vivekanand Jha, Wolfgang Kuhn, Hasko Stenzel, O. Malyshev, A. A. Sokolov, U. Kurilla, G. Kuhl, D. Kaiser, P. Strzempek, A. Goerres, J. Biernat, D. G. Ireland, H. Xu, M. K. Suleimanov, G. Sterzenbach, E. Prencipe, A. Ortiz, N. I. Zhuravlev, A. Täschner, A. Gerasimov, T. Triffterer, M. Deiseroth, A. Wilson, Marek Palka, M. Lindemulder, A. Y. Barnyakov, V.Kh. Dodokhov, D. Nicmorus, Andrey Uzunian, A. Ehret, R. Nellen, Ch. Hammann, M. Steinke, V. L. Malyshev, P. Drexler, Richard Wheadon, A. Cotta Ramusino, P. Sarin, Riccardo Introzzi, H. Clement, I. Kulakov, M. Zuehlsdorf, M. Galuska, S. Kliczewski, G.B. Pontecorvo, D. Przyborowski, Mihai Caprini, V. V. Mochalov, M. Jadhav, M. Mikirtychyants, M. Traxler, Frank Goldenbaum, Research unit Nuclear & Hadron Physics, The PANDA Collaboration, Null, Singh, B. P, Erni, W., Keshelashvili, I., Krusche, B., Steinacher, M., Liu, B., Liu, H., Liu, Z., Shen, X., Wang, C., Zhao, J., Albrecht, M., Fink, M., Heinsius, F. H., Held, T., Holtmann, T., Koch, H., Kopf, B., Kümmel, M., Kuhl, G., Kuhlmann, M., Leyhe, M., Mikirtychyants, M., Musiol, P., Mustafa, A., Pelizäus, M., Pychy, J., Richter, M., Schnier, C., Schröder, T., Sowa, C., Steinke, M., Triffterer, T., Wiedner, U., Beck, R., Hammann, C., Kaiser, D., Ketzer, B., Kube, M., Mahlberg, P., Rossbach, M., Schmidt, C., Schmitz, R., Thoma, U., Walther, D., Wendel, C., Wilson, A., Bianconi, A., Bragadireanu, M., Caprini, M., Pantea, D., Pietreanu, D., Vasile, M. E., Patel, B., Kaplan, D., Brandys, P., Czyzewski, T., Czyzycki, W., Domagala, M., Hawryluk, M., Filo, G., Krawczyk, M., Kwiatkowski, D., Lisowski, E., Lisowski, F., Fiutowski, T., Idzik, M., Mindur, B., Przyborowski, D., Swientek, K., Czech, B., Kliczewski, S., Korcyl, K., Kozela, A., Kulessa, P., Lebiedowicz, P., Malgorzata, K., Pysz, K., Schäfer, W., Siudak, R., Szczurek, A., Biernat, J., Jowzaee, S., Kamys, B., Kistryn, S., Korcyl, G., Krzemien, W., Magiera, A., Moskal, P., Palka, M., Psyzniak, A., Rudy, Z., Salabura, P., Smyrski, J., Strzempek, P., Wrońska, A., Augustin, I., Lehmann, I., Nicmorus, D., Schepers, G., Schmitt, L., Al Turany, M., Cahit, U., Capozza, L., Dbeyssi, A., Deppe, H., Dzhygadlo, R., Ehret, A., Flemming, H., Gerhardt, A., Götzen, K., Karabowicz, R., Kliemt, R., Kunkel, J., Kurilla, U., Lehmann, D., Lühning, J., Maas, F., Morales Morales, C., Mora Espí, M. C., Nerling, F., Orth, H., Peters, K., Rodríguez Piñeiro, D., Saito, N., Saito, T., Sánchez Lorente, A., Schmidt, C. J., Schwarz, C., Schwiening, J., Traxler, M., Valente, R., Voss, B., Wieczorek, P., Wilms, A., Zühlsdorf, M., Abazov, V. M., Alexeev, G., Arefiev, A., Astakhov, V. I., Barabanov, M. Y. u., Batyunya, B. V., Davydov, Y. u. I., Dodokhov, V. K. h., Efremov, A. A., Fedunov, A. G., Festchenko, A. A., Galoyan, A. S., Grigoryan, S., Karmokov, A., Koshurnikov, E. K., Lobanov, V. I., Lobanov, Y. u. Y. u., Makarov, A. F., Malinina, L. V., Malyshev, V. L., Mustafaev, G. A., Olshevskiy, A., Pasyuk, M. A., Perevalova, E. A., Piskun, A. A., Pocheptsov, T. A., Pontecorvo, G., Rodionov, V. K., Rogov, Y. u. N., Salmin, R. A., Samartsev, A. G., Sapozhnikov, M. G., Shabratova, G. S., Skachkov, N. B., Skachkova, A. N., Strokovsky, E. A., Suleimanov, M. K., Teshev, R. S. h., Tokmenin, V. V., Uzhinsky, V. V., Vodopyanov, A. S., Zaporozhets, S. A., Zhuravlev, N. I., Zorin, A. G., Branford, D., Glazier, D., Watts, D., Woods, P., Britting, A., Eyrich, W., Lehmann, A., Uhlig, F., Dobbs, S., Seth, K., Tomaradze, A., Xiao, T., Bettoni, D., Carassiti, V., Cotta Ramusino, A., Dalpiaz, P., Drago, A., Fioravanti, E., Garzia, I., Savriè, M., Stancari, G., Akishina, V., Kisel, I., Kulakov, I., Zyzak, M., Arora, R., Bel, T., Gromliuk, A., Kalicy, G., Krebs, M., Patsyuk, M., Zuehlsdorf, M., Bianchi, N., Gianotti, P., Guaraldo, C., Lucherini, V., Pace, E., Bersani, A., Bracco, G., Macri, M., Parodi, R. F., Bianco, S., Bremer, D., Brinkmann, K. T., Diehl, S., Dormenev, V., Drexler, P., Düren, M., Eissner, T., Etzelmüller, E., Föhl, K., Galuska, M., Gessler, T., Gutz, E., Hayrapetyan, A., Hu, J., Kröck, B., Kühn, W., Kuske, T., Lange, S., Liang, Y., Merle, O., Metag, V., Mülhheim, D., Münchow, D., Nanova, M., Novotny, R., Pitka, A., Quagli, T., Rieke, J., Rosenbaum, C., Schnell, R., Spruck, B., Stenzel, H., Thöring, U., Ullrich, M., Wasem, T., Werner, M., Zaunick, H. G., Ireland, D., Rosner, G., Seitz, B., Deepak, P. N., Kulkarni, A. V., Apostolou, A., Babai, M., Kavatsyuk, M., Lemmens, P., Lindemulder, M., Löhner, H., Messchendorp, J., Schakel, P., Smit, H., van der Weele, J. C., Tiemens, M., Veenstra, R., Vejdani, S., Kalita, K., Mohanta, D. P., Kumar, A., Roy, A., Sahoo, R., Sohlbach, H., Büscher, M., Cao, L., Cebulla, A., Deermann, D., Dosdall, R., Esch, S., Georgadze, I., Gillitzer, A., Goerres, A., Goldenbaum, F., Grunwald, D., Herten, A., Hu, Q., Kemmerling, G., Kleines, H., Kozlov, V., Lehrach, A., Leiber, S., Maier, R., Nellen, R., Ohm, H., Orfanitski, S., Prasuhn, D., Prencipe, E., Ritman, J., Schadmand, S., Schumann, J., Sefzick, T., Serdyuk, V., Sterzenbach, G., Stockmanns, T., Wintz, P., Wüstner, P., Xu, H., Li, S., Li, Z., Sun, Z., Rigato, V., Fissum, S., Hansen, K., Isaksson, L., Lundin, M., Schröder, B., Achenbach, P., Bleser, S., Cardinali, M., Corell, O., Deiseroth, M., Denig, A., Distler, M., Feldbauer, F., Fritsch, M., Jasinski, P., Hoek, M., Kangh, D., Karavdina, A., Lauth, W., Leithoff, H., Merkel, H., Michel, M., Motzko, C., Müller, U., Noll, O., Plueger, S., Pochodzalla, J., Sanchez, S., Schlimme, S., Sfienti, C., Steinen, M., Thiel, M., Weber, T., Zambrana, M., Dormenev, V. I., Fedorov, A. A., Korzihik, M. V., Missevitch, O. V., Balanutsa, P., Balanutsa, V., Chernetsky, V., Demekhin, A., Dolgolenko, A., Fedorets, P., Gerasimov, A., Goryachev, V., Varentsov, V., Boukharov, A., Malyshev, O., Marishev, I., Semenov, A., Konorov, I., Paul, S., Grieser, S., Hergemöller, A. K., Khoukaz, A., Köhler, E., Täschner, A., Wessels, J., Dash, S., Jadhav, M., Kumar, S., Sarin, P., Varma, R., Chandratre, V. B., Datar, V., Dutta, D., Jha, V., Kumawat, H., Mohanty, A. K., Roy, B., Yan, Y., Chinorat, K., Khanchai, K., Ayut, L., Pornrad, S., Barnyakov, A. Y., Blinov, A. E., Blinov, V. E., Bobrovnikov, V. S., Kononov, S. A., Kravchenko, E. A., Kuyanov, I. A., Onuchin, A. P., Sokolov, A. A., Tikhonov, Y. A., Atomssa, E., Hennino, T., Imre, M., Kunne, R., Le Galliard, C., Ma, B., Marchand, D., Ong, S., Ramstein, B., Rosier, P., Tomasi Gustafsson, E., Van de Wiele, J., Boca, G., Costanza, S., Genova, P., Lavezzi, L., Montagna, P., Rotondi, A., Abramov, V., Belikov, N., Bukreeva, S., Davidenko, A., Derevschikov, A., Goncharenko, Y., Grishin, V., Kachanov, V., Kormilitsin, V., Melnik, Y., Levin, A., Minaev, N., Mochalov, V., Morozov, D., Nogach, L., Poslavskiy, S., Ryazantsev, A., Ryzhikov, S., Semenov, P., Shein, I., Uzunian, A., Vasiliev, A., Yakutin, A., Yabsley, B., Bäck, T., Cederwall, B., Makónyi, K., Tegnér, P. E., von Würtemberg, K. M., Belostotski, S., Gavrilov, G., Izotov, A., Kashchuk, A., Levitskaya, O., Manaenkov, S., Miklukho, O., Naryshkin, Y., Suvorov, K., Veretennikov, D., Zhadanov, A., Rai, A. K., Godre, S. S., Duchat, R., Amoroso, A., Bussa, M. P., Busso, L., De Mori, F., Destefanis, M., Fava, L., Ferrero, L., Greco, M., Maggiora, M., Maniscalco, G., Marcello, S., Sosio, S., Spataro, S., Zotti, L., Calvo, D., Coli, S., De Remigis, P., Filippi, A., Giraudo, G., Lusso, S., Mazza, G., Mingnore, M., Rivetti, A., Wheadon, R., Balestra, F., Iazzi, F., Introzzi, R., Lavagno, A., Younis, H., Birsa, Renato, Bradamante, Franco, Bressan, Andrea, Martin, Anna, Clement, H., Gålnander, B., Caldeira Balkeståhl, L., Calén, H., Fransson, K., Johansson, T., Kupsc, A., Marciniewski, P., Pettersson, J., Schönning, K., Wolke, M., Zlomanczuk, J., Díaz, J., Ortiz, A., Vinodkumar, P. C., Parmar, A., Chlopik, A., Melnychuk, D., Slowinski, B., Trzcinski, A., Wojciechowski, M., Wronka, S., Zwieglinski, B., Bühler, P., Marton, J., Suzuki, K., Widmann, E., Zmeskal, J., Fröhlich, B., Khaneft, D., Lin, D., Zimmermann, I., and Semenov Tian Shansky, K.
Subjects: Particle physics, (P)Over-Baranda, Nuclear and High Energy Physics, Electroproduction, Hadron, Annihilation, FOS: Physical sciences, 7. Clean energy, 01 natural sciences, Particle identification, Nucleon, NO, Nuclear physics, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), Factorization, 0103 physical sciences, Fysik, Invariant mass, ddc:530, Meson Production, Monte-Carlo, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Physics, Quantum chromodynamics, 010308 nuclear & particles physics, Perturbative QCD, Qcd, Physical Sciences, Exclusive Processes, High Energy Physics::Experiment, Pi(0), Cross-Sections, Energy (signal processing)
Abstract: Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuable new information on hadron structure appear as building blocks in the collinear factorized description for several types of hard exclusive reactions. In this paper, we address the possibility of accessing nucleon-to-pion ($��N$) TDAs from $\bar{p}p \to e^+e^- ��^0$ reaction with the future PANDA detector at the FAIR facility. At high center of mass energy and high invariant mass squared of the lepton pair $q^2$, the amplitude of the signal channel $\bar{p}p \to e^+e^- ��^0$ admits a QCD factorized description in terms of $��N$ TDAs and nucleon Distribution Amplitudes (DAs) in the forward and backward kinematic regimes. Assuming the validity of this factorized description, we perform feasibility studies for measuring $\bar{p}p \to e^+e^- ��^0$ with the PANDA detector. Detailed simulations on signal reconstruction efficiency as well as on rejection of the most severe background channel, i.e. $\bar{p}p \to ��^+��^- ��^0$ were performed for the center of mass energy squared $s = 5$ GeV$^2$ and $s = 10$ GeV$^2$, in the kinematic regions $3.0 < q^2 < 4.3$ GeV$^2$ and $5 < q^2 < 9$ GeV$^2$, respectively, with a neutral pion scattered in the forward or backward cone $| \cos��_{��^0}| > 0.5 $ in the proton-antiproton center of mass frame. Results of the simulation show that the particle identification capabilities of the PANDA detector will allow to achieve a background rejection factor of $5\cdot 10^7$ ($1\cdot 10^7$) at low (high) $q^2$ for $s=5$ GeV$^2$, and of $1\cdot 10^8$ ($6\cdot 10^6$) at low (high) $q^2$ for $s=10$ GeV$^2$, while keeping the signal reconstruction efficiency at around $40\%$. At both energies, a clean lepton signal can be reconstructed with the expected statistics corresponding to $2$ fb$^{-1}$ of integrated luminosity. (.../...), 19 pages, 7 figures (some multiple), 2 tables (each double), preprint of an article for epj - v2
Published: 2015
Full Text: View/download PDF

34. Three-body nature of N() and Δ() resonances from sequential decay chains

Author: A, Thiel, V, Sokhoyan, E, Gutz, H, van Pee, A V, Anisovich, J C S, Bacelar, B, Bantes, O, Bartholomy, D, Bayadilov, R, Beck, Yu, Beloglazov, R, Castelijns, V, Crede, H, Dutz, D, Elsner, R, Ewald, F, Frommberger, M, Fuchs, Ch, Funke, R, Gregor, A, Gridnev, W, Hillert, Ph, Hoffmeister, I, Horn, I, Jaegle, J, Junkersfeld, H, Kalinowsky, S, Kammer, V, Kleber, Frank, Klein, Friedrich, Klein, E, Klempt, M, Kotulla, B, Krusche, M, Lang, H, Löhner, I, Lopatin, S, Lugert, T, Mertens, J G, Messchendorp, V, Metag, B, Metsch, M, Nanova, V, Nikonov, D, Novinski, R, Novotny, M, Ostrick, L, Pant, M, Pfeiffer, D, Piontek, A, Roy, A V, Sarantsev, Ch, Schmidt, H, Schmieden, S, Shende, A, Süle, V V, Sumachev, T, Szczepanek, U, Thoma, D, Trnka, R, Varma, D, Walther, Ch, Wendel, and A, Wilson
Abstract: The Nπ^{0}π^{0} decays of positive-parity N^{*} and Δ^{*} resonances at about 2 GeV are studied at ELSA by photoproduction of two neutral pions off protons. The data reveal clear evidence for several intermediate resonances: Δ(1232), N(1520)3/2^{-}, and N(1680)5/2^{+}, with spin parities J^{P}=3/2^{+}, 3/2^{-}, and 5/2^{+}. The partial wave analysis (within the Bonn-Gatchina approach) identifies N(1440)1/2^{+} and the N(ππ)_{S wave} (abbreviated as Nσ here) as further isobars and assigns the final states to the formation of nucleon and Δ resonances and to nonresonant contributions. We observe the known Δ(1232)π decays of Δ(1910)1/2^{+}, Δ(1920)3/2^{+}, Δ(1905)5/2^{+}, Δ(1950)7/2^{+}, and of the corresponding spin-parity series in the nucleon sector, N(1880)1/2^{+}, N(1900)3/2^{+}, N(2000)5/2^{+}, and N(1990)7/2^{+}. For the nucleon resonances, these decay modes are reported here for the first time. Further new decay modes proceed via N(1440)1/2^{+}π, N(1520)3/2^{-}π, N(1680)5/2^{+}π, and Nσ. The latter decay modes are observed in the decay of N^{*} resonances and at most weakly in Δ^{*} decays. It is argued that these decay modes provide evidence for a 3-quark nature of N^{*} resonances rather than a quark-diquark structure.
Published: 2014

35. N(1520)3/2−Helicity Amplitudes from an Energy-Independent Multipole Analysis Based on New Polarization Data on Photoproduction of Neutral Pions

Author: Ph. Thämer, Ch. Honisch, Ch. Schmidt, J. Hannappel, A. V. Anisovich, V. A. Nikonov, A. V. Sarantsev, H. Schmieden, Alastair J. Wilson, T. C. Jude, Ulrich Wiedner, D. E. Bayadilov, Lilian Witthauer, A. B. Gridnev, Mariana Nanova, M. Kube, A. Thiel, A. Käser, U. Thoma, K. Makonyi, Francesco Messi, K.-Th. Brinkmann, M. Grüner, Ch. Hammann, Matthew Lang, K. Fornet-Ponse, H. van Pee, K. Koop, M. Becker, Yu. A. Beloglazov, S. Böse, H. Kalinowsky, G. Reicherz, A. Berlin, E. Gutz, D. V. Novinski, Friedrich Klein, F. Kalischewski, A. Winnebeck, P. Klassen, M. Urban, T. Rostomyan, M. Gottschall, D. Elsner, D. Walther, V. Sokhoyan, W. Meyer, V. Metag, T. Seifen, R. W. Novotny, Ph. Hoffmeister, Ch. Funke, B. Krusche, Friedrich, Eberhard Klempt, B. Roth, M. Bichow, Reinhard Beck, Wolfgang Hillert, M. Dieterle, Y. Wunderlich, Ch. Wendel, Frank Frommberger, D. Piontek, I. V. Lopatin, H. Dutz, H. Eberhardt, V. Crede, I. Keshelashvili, Jörg H. Müller, Jens Hartmann, D. Kaiser, R. Schmitz, C. Rosenbaum, O. Jahn, V. Hannen, and J. Herick
Subjects: Physics, 010308 nuclear & particles physics, Linear polarization, Partial wave analysis, General Physics and Astronomy, Electron, Polarization (waves), 01 natural sciences, Helicity, Nuclear physics, Amplitude, Pion, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Multipole expansion
Abstract: New data on the polarization observables T, P, and H for the reaction γp→pπ0 are reported. The results are extracted from azimuthal asymmetries when a transversely polarized butanol target and a linearly polarized photon beam are used. The data were taken at the Bonn electron stretcher accelerator ELSA using the CBELSA/TAPS detector. These and earlier data are used to perform a truncated energy-independent partial wave analysis in sliced-energy bins. This energy-independent analysis is compared to the results from energy-dependent partial wave analyses.
Published: 2014
Full Text: View/download PDF

36. High statistics study of the reaction γp → pπ0 η

Author: E. Gutz, A. Süle, B. Bantes, S. Lugert, D. Elsner, R. Castelijns, R. W. Novotny, H. Schmieden, Ph. Hoffmeister, Eberhard Klempt, Frank Klein, B. Krusche, D. E. Bayadilov, A. B. Gridnev, O. Bartholomy, R. Gregor, M. Kotulla, Yu. A. Beloglazov, A. Wilson, J. C. S. Bacelar, A. V. Sarantsev, M. Ostrick, D. Trnka, Matthew Lang, T. Szczepanek, Ankhi Roy, A. V. Anisovich, Lalit Mohan Pant, Frank Frommberger, R. Varma, U. Thoma, M. Fuchs, V. Crede, D. Novinsky, V. Sokhoyan, J. Junkersfeld, V. Kleber, R. Beck, H. Dutz, Wolfgang Hillert, V. A. Nikonov, S. Shende, M. Pfeiffer, Ch. Wendel, S. Kammer, V. V. Sumachev, Ch. Funke, M. Nanova, I. Jaegle, R. Ewald, A. Thiel, I. Horn, H. van Pee, H. Kalinowsky, D. Walther, T. Mertens, Herbert Löhner, V. Metag, J. G. Messchendorp, D. Piontek, Ch. Schmidt, I. V. Lopatin, and Friedrich Klein
Subjects: Physics, Nuclear and High Energy Physics, Photon, Meson, 010308 nuclear & particles physics, Partial wave analysis, Nuclear Theory, Hadron, Dalitz plot, Electron, 01 natural sciences, Nuclear physics, 0103 physical sciences, Isobar, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: Photoproduction off protons of the pπ 0 η three-body final state was studied with the Crystal Barrel/TAPS detector, at the electron stretcher accelerator ELSA in Bonn, for incident energies from the π 0 η production threshold up to 2.5 GeV. Differential cross sections and the total cross sections are presented. The use of linearly polarized photons gives access to the polarization observables Σ, I s , and I c , the latter two characterize beam asymmetries in case of three-body final states. Δ(1232)η, N(1535)1/2− π, and pa 0(980) are the dominant isobars contributing to the reaction. The partial wave analysis confirms the existence of some nucleon and Δ resonances, for which so far only fair evidence was reported. A large number of decay modes of known nucleon and Δ resonances is presented. It is shown that detailed investigations of decay branching ratios may provide a key to unravelling the structure of nucleon and Δ resonances.
Published: 2014
Full Text: View/download PDF

37. N(1520) 3/2(-) helicity amplitudes from an energy-independent multipole analysis based on new polarization data on photoproduction of neutral pions

Author: J, Hartmann, H, Dutz, A V, Anisovich, D, Bayadilov, R, Beck, M, Becker, Y, Beloglazov, A, Berlin, M, Bichow, S, Böse, K-Th, Brinkmann, V, Crede, M, Dieterle, H, Eberhardt, D, Elsner, K, Fornet-Ponse, St, Friedrich, F, Frommberger, Ch, Funke, M, Gottschall, A, Gridnev, M, Grüner, E, Gutz, Ch, Hammann, J, Hannappel, V, Hannen, J, Herick, W, Hillert, Ph, Hoffmeister, Ch, Honisch, O, Jahn, T, Jude, A, Käser, D, Kaiser, H, Kalinowsky, F, Kalischewski, P, Klassen, I, Keshelashvili, F, Klein, E, Klempt, K, Koop, B, Krusche, M, Kube, M, Lang, I, Lopatin, K, Makonyi, F, Messi, V, Metag, W, Meyer, J, Müller, M, Nanova, V, Nikonov, D, Novinski, R, Novotny, D, Piontek, C, Rosenbaum, B, Roth, G, Reicherz, T, Rostomyan, A, Sarantsev, Ch, Schmidt, H, Schmieden, R, Schmitz, T, Seifen, V, Sokhoyan, Ph, Thämer, A, Thiel, U, Thoma, M, Urban, H, van Pee, D, Walther, Ch, Wendel, U, Wiedner, A, Wilson, A, Winnebeck, L, Witthauer, and Y, Wunderlich
Abstract: New data on the polarization observables T, P, and H for the reaction γp→pπ(0) are reported. The results are extracted from azimuthal asymmetries when a transversely polarized butanol target and a linearly polarized photon beam are used. The data were taken at the Bonn electron stretcher accelerator ELSA using the CBELSA/TAPS detector. These and earlier data are used to perform a truncated energy-independent partial wave analysis in sliced-energy bins. This energy-independent analysis is compared to the results from energy-dependent partial wave analyses.
Published: 2014

38. First Measurement of the Helicity Asymmetry forγp→pπ0in the Resonance Region

Author: R. W. Novotny, Ph. Hoffmeister, K. Makonyi, A. V. Anisovich, K.-Th. Brinkmann, K. Fornet-Ponse, H. van Pee, K. Koop, Frank Klein, M. Urban, V. Crede, Matthew Lang, Friedrich, A. Wilson, V. Sokhoyan, Yasser Maghrbi, H. Dutz, R. Schmitz, R. Ewald, D. Piontek, R. Beck, W. Meyer, G. Reicherz, H. Schmieden, D. E. Bayadilov, H. Eberhardt, I. V. Lopatin, T. Seifen, H. Kalinowsky, A. B. Gridnev, Mariana Nanova, J. Hannappel, D. Kaiser, I. Jaegle, J. Mueller, Ulrich Wiedner, U. Thoma, M. Gruener, Frank Frommberger, Jens Hartmann, Wolfgang Hillert, V. Metag, M. Gottschall, T. Rostomyan, E. Gutz, I. Keshelashvili, M. Bichow, A. V. Sarantsev, D. Walther, B. Bantes, S. Boese, V. A. Nikonov, A. Thiel, Eberhard Klempt, Ch. Hammann, A. Winnebeck, M. Kube, Ch. Honisch, Ch. Schmidt, S. Kammer, F. Dietz, Th. Challand, Ch. Funke, B. Krusche, Ch. Wendel, Schaepe, and D. Elsner
Subjects: Physics, Photon, 010308 nuclear & particles physics, media_common.quotation_subject, Nuclear Theory, Solid angle, General Physics and Astronomy, Resonance, 01 natural sciences, Asymmetry, Helicity, Nuclear physics, Cross section (physics), Amplitude, Pion, 0103 physical sciences, Nuclear Experiment, 010306 general physics, media_common
Abstract: The first measurement of the helicity dependence of the photoproduction cross section of single neutral pions off protons is reported for photon energies from 600 to 2300 MeV, covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, and BnGa partial wave analyses. Strikingly large differences between data and predictions are observed, which are traced to differences in the helicity amplitudes of well-known and established resonances. Precise values for the helicity amplitudes of several resonances are reported.
Published: 2014
Full Text: View/download PDF

39. Measurement of the beam asymmetry Σ in πeta; production off the proton with the CBELSA/TAPS experiment⋆

Author: C. Morales, S. Schadmand, D. Novinsky, R. Beck, A. Ehmanns, M. Konrad, K. Essig, Frank Klein, A. Süle, T. Szczepanek, J. Junkersfeld, Lalit Mohan Pant, S.V. Shende, V. Sokhoyan, M. Fuchs, I. V. Lopatin, V. V. Sumachev, Yu. A. Beloglazov, M. Ostrick, H. Schmieden, Ch. Wendel, V. Metag, Friedrich Klein, D. E. Bayadilov, A. V. Sarantsev, A. B. Gridnev, M. Kotulla, R. Castelijns, I. Jägle, U. Thoma, M. Pfeiffer, Matthew Lang, O. Bartholomy, A. Radkov, R. Novotny, H. Dutz, V. Crede, M. Nanova, H. Kalinowsky, D. Menze, V. Kleber, K. Fornet-Ponse, R. Gregor, J. Langheinrich, J. C. S. Bacelar, S. Lugert, D. Walther, I. Fabry, A. V. Anisovich, Ch. Schmidt, J. Lotz, J. G. Messchendorp, D. Trnka, S. Kammer, R. Ewald, Ch. Funke, H. van Pee, I. Horn, Ch. Weinheimer, R. W. Gothe, T. Mertens, Herbert Löhner, B. Krusche, E. Gutz, B. Bantes, V. A. Nikonov, D. Elsner, Ph. Hoffmeister, Eberhard Klempt, B. Schoch, and S. Höffgen
Subjects: Physics, Nuclear and High Energy Physics, Photon, Proton, media_common.quotation_subject, Bremsstrahlung, Particle accelerator, Asymmetry, Resonance (particle physics), law.invention, Nuclear physics, Pair production, law, Atomic physics, Nuclear Experiment, Beam (structure), media_common
Abstract: In photoproduction experiments, a large number of final states yielding various resonance contributions are accessible. To extract resonance parameters via partial-wave analysis not only the measurement of differential cross-sections is necessary, but also the determination of polarization observables. At the electron accelerator ELSA (Bonn) the coherent bremsstrahlung method was used to generate a linearly polarized photon beam. Using the CBELSA/TAPS detector setup, the beam asymmetry Σ in the reaction γp → pπ 0 η was determined as a function of various masses and angles for photon energies between 970MeV and 1650MeV.
Published: 2008
Full Text: View/download PDF

40. First measurement of the helicity asymmetry for γp → pπ0 in the resonance region

Author: M, Gottschall, A V, Anisovich, B, Bantes, D, Bayadilov, R, Beck, M, Bichow, S, Böse, K-Th, Brinkmann, Th, Challand, V, Crede, F, Dietz, H, Dutz, H, Eberhardt, D, Elsner, R, Ewald, K, Fornet-Ponse, St, Friedrich, F, Frommberger, Ch, Funke, A, Gridnev, M, Grüner, E, Gutz, Ch, Hammann, J, Hannappel, J, Hartmann, W, Hillert, Ph, Hoffmeister, Ch, Honisch, I, Jaegle, D, Kaiser, H, Kalinowsky, S, Kammer, I, Keshelashvili, F, Klein, E, Klempt, K, Koop, B, Krusche, M, Kube, M, Lang, I, Lopatin, Y, Maghrbi, K, Makonyi, V, Metag, W, Meyer, J, Müller, M, Nanova, V, Nikonov, R, Novotny, D, Piontek, G, Reicherz, T, Rostomyan, A, Sarantsev, St, Schaepe, Ch, Schmidt, H, Schmieden, R, Schmitz, T, Seifen, V, Sokhoyan, A, Thiel, U, Thoma, M, Urban, H, van Pee, D, Walther, Ch, Wendel, U, Wiedner, A, Wilson, and A, Winnebeck
Abstract: The first measurement of the helicity dependence of the photoproduction cross section of single neutral pions off protons is reported for photon energies from 600 to 2300 MeV, covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, and BnGa partial wave analyses. Strikingly large differences between data and predictions are observed, which are traced to differences in the helicity amplitudes of well-known and established resonances. Precise values for the helicity amplitudes of several resonances are reported.
Published: 2013

41. Thielet al.Reply

Author: G. Reicherz, F. Kalischewski, Yu. A. Beloglazov, V. Metag, A. V. Sarantsev, J. Hannappel, U. Thoma, H. Schmieden, D. E. Bayadilov, James Mueller, W. Meyer, Mariana Nanova, Eberhard Klempt, V. Kleber, Wolfgang Hillert, M. Bichow, Matthew Lang, I. Juergensen, D. Walther, A. V. Anisovich, D. Kaiser, D. Piontek, M. Gottschall, I. V. Lopatin, A. Thiel, U. Wiedner, Y. Wunderlich, S. Boese, H. Kalinowsky, D. Elsner, Jens Hartmann, V. A. Nikonov, K. Fornet-Ponse, R. W. Novotny, Ph. Hoffmeister, I. Keshelashvili, R. Beck, E. Gutz, Ch. Honisch, Ch. Schmidt, H. vanPee, Ch. Hammann, B. Bantes, V. Sokhoyan, B. Krusche, Ch. Wendel, P. Drexler, V. V. Sumachev, S. Kammer, A. Winnebeck, F. Dietz, Th. Challand, Ch. Funke, Frank Frommberger, Frank Klein, Friedrich, K. Makonyi, K.-Th. Brinkmann, T. Seifen, I. Jaegle, M. Gruener, Yasser Maghrbi, H. Dutz, H. Eberhardt, V. Crede, R. Ewald, and Alastair J. Wilson
Subjects: Physics, 010308 nuclear & particles physics, Quantum electrodynamics, 0103 physical sciences, General Physics and Astronomy, 010306 general physics, Polarization (waves), Nucleon, 01 natural sciences
Published: 2013
Full Text: View/download PDF

42. Well-established nucleon resonances revisited by double-polarization measurements

Author: K. Makonyi, E. Gutz, Jens Hartmann, K.-Th. Brinkmann, Ch. Wendel, V. V. Sumachev, H. Kalinowsky, U. Thoma, T. Seifen, R. Beck, I. Juergensen, I. Jaegle, V. A. Nikonov, M. Gruener, W. Meyer, B. Krusche, A. Thiel, Friedrich, D. Piontek, D. Elsner, U. Wiedner, B. Bantes, Eberhard Klempt, I. V. Lopatin, R. W. Novotny, Ph. Hoffmeister, V. Metag, A. V. Anisovich, K. Fornet-Ponse, V. Crede, M. Bichow, M. Gottschall, Frank Frommberger, Yu. A. Beloglazov, A. V. Sarantsev, Yasser Maghrbi, S. Kammer, Ch. Hammann, P. Drexler, A. Winnebeck, F. Dietz, H. Dutz, Th. Challand, Ch. Funke, H. Eberhardt, I. Keshelashvili, G. Reicherz, Friedrich Klein, J. Hannappel, D. Kaiser, Ch. Honisch, Ch. Schmidt, H. vanPee, V. Sokhoyan, R. Ewald, Wolfgang Hillert, Alastair J. Wilson, D. Walther, S. Boese, Y. Wunderlich, James Mueller, Matthew Lang, F. Kalischewski, H. Schmieden, D. E. Bayadilov, Mariana Nanova, and V. Kleber
Subjects: Physics, Photon, Partial wave analysis, Nuclear Theory, General Physics and Astronomy, Resonance, FOS: Physical sciences, Photon energy, Baryon, Nuclear physics, Pion, Photon polarization, Atomic physics, Nuclear Experiment (nucl-ex), Nucleon, Nuclear Experiment
Abstract: The first measurement is reported of the double-polarization observable G in photoproduction of neutral pions off protons, covering the photon energy range from 620 to 1120 MeV and the full solid angle. G describes the correlation between the photon polarization plane and the scattering plane for protons polarized along the direction of the incoming photon. The observable is highly sensitive to contributions from baryon resonances. The new results are compared to the predictions from SAID, MAID, and BnGa partial wave analyses. In spite of the long-lasting efforts to understand {\gamma}p -> p{\pi} 0 as the simplest photoproduction reaction, surprisingly large differences between the new data and the latest predictions are observed which are traced to different contributions of the N (1535) with spin-parity J^P = 1/2^- and N (1520) with J^P = 3/2^- . In the third resonance region, where N (1680) with J^P = 5/2^+ production dominates, the new data are reasonably close to the predictions., Comment: Submitted for publication in PRL
Published: 2012
Full Text: View/download PDF

43. Quasi-free photoproduction of eta-mesons off the deuteron

Author: D. Walther, U. Thoma, V. Crede, F. Frommberger, D. V. Novinski, S. Schadmand, V. Sokhoyan, V. Metag, S. Lugert, S. Kammer, B. Krusche, L. M. Pant, Yu. A. Beloglazov, Wolfgang Hillert, Eberhard Klempt, J. C. S. Bacelar, R. Castelijns, R. W. Gothe, S. Höffgen, Lilian Witthauer, R. Ewald, Ch. Funke, D. Elsner, O. Bartholomy, R. W. Novotny, Ph. Hoffmeister, H. Kalinowsky, R. Gregor, A. V. Anisovich, Frank Klein, J. Junkersfeld, B. Schoch, E. Gutz, M. Dieterle, T. Mertens, D. Menze, Herbert Löhner, A. V. Sarantsev, H. Schmieden, M. Pfeiffer, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, A. Roy, D. Trnka, H. van Pee, Ch. Wendel, Friedrich Klein, T. Szczepanek, V. V. Sumachev, V. A. Nikonov, R. Beck, I. Horn, M. Kotulla, B. Bantes, M. Konrad, Matthew Lang, V. Kleber, I. Jaegle, F. Pheron, S. V. Shende, Yasser Maghrbi, H. Dutz, D. Werthmüller, I. Keshelashvili, I. V. Lopatin, J. G. Messchendorp, R. Varma, M. Oberle, A. Süle, Ch. Schmidt, M. Ostrick, KVI - Center for Advanced Radiation Technology, and Research unit Nuclear & Hadron Physics
Subjects: Nuclear reaction, Nuclear and High Energy Physics, Proton, Meson, Hadron, Nuclear Theory, NUCLEON RESONANCE, FOS: Physical sciences, Photon energy, PROTON, ELSA, REGION, Nuclear physics, Effective mass (solid-state physics), Neutron, Nuclear Experiment (nucl-ex), Nuclear Experiment, Physics, NEAR-THRESHOLD PHOTOPRODUCTION, CHIRAL DYNAMICS, EXCLUSIVE MEASUREMENT, POLARIZED PHOTON BEAMS, BARYON RESONANCES, ASYMMETRY, High Energy Physics::Experiment, Nucleon
Abstract: Precise data for quasi-free photoproduction of $\eta$ mesons off the deuteron have been measured at the Bonn ELSA accelerator with the combined Crystal Barrel/TAPS detector for incident photon energies up to 2.5 GeV. The $\eta$-mesons have been detected in coincidence with recoil protons and neutrons. Possible nuclear effects like Fermi motion and re-scattering can be studied via a comparison of the quasi-free reaction off the bound proton to $\eta$-production off the free proton. No significant effects beyond the folding of the free cross section with the momentum distribution of the bound protons have been found. These Fermi motion effects can be removed by an analysis using the invariant mass of the $\eta$-nucleon pairs reconstructed from the final state four-momenta of the particles. The total cross section for quasi-free $\eta$-photoproduction off the neutron reveals even without correction for Fermi motion a pronounced bump-like structure around 1 GeV of incident photon energy, which is not observed for the proton. This structure is even narrower in the invariant mass spectrum of the $\eta$-neutron pairs. Position and width of the peak in the invariant mass spectrum are $W\approx 1665$ MeV and FWHM $\Gamma\approx 25$ MeV. The data are compared to the results of different models., Comment: accepted for publication in Eur. Phys. J. A
Published: 2011
Full Text: View/download PDF

44. Photoproduction of Neutral Pions off Protons

Author: T. Mertens, Herbert Löhner, E. Gutz, V. A. Nikonov, H. Schmieden, Wolfgang Hillert, M. Ostrick, S. Schadmand, Frank Klein, D. E. Bayadilov, Yu. A. Beloglazov, H. Kalinowsky, A. V. Sarantsev, J. C. S. Bacelar, A. Wilson, A. B. Gridnev, D. V. Novinski, H. van Pee, R. Bantes, Mariana Nanova, V. Crede, N. Sparks, V. Sokhoyan, H. Dutz, A. Suele, D. Elsner, Ch. Schmidt, I. Jaegle, Frank Frommberger, R. Varma, R. Castelijns, R. W. Novotny, Ph. Hoffmeister, D. Menze, B. Krusche, R. Gregor, A. V. Anisovich, Friedrich Klein, Volker Metag, S. Shende, S. Kammer, B. Schoch, Ch. Wendel, C. Funke, V. V. Sumachev, M. Pfeiffer, O. Bartholomy, D. Walther, S. Lugert, L. M. Pant, M. Kotulla, Johannes Messchendorp, U. Thoma, Eberhard Klempt, J. Junkersfeld, A. Roy, I. V. Lopatin, R. Beck, R. Ewald, D. Trnka, T. Szczepanek, KVI - Center for Advanced Radiation Technology, and Research unit Nuclear & Hadron Physics
Subjects: Nuclear and High Energy Physics, Particle physics, N(2190), Photon, tagged beam [photon], Meson, 0.85-2.50 GeV, Partial wave analysis, electromagnetic [calorimeter], NUCLEON RESONANCE, FOS: Physical sciences, photoproduction [pi0], +p+pi0%22">photon p --> p pi0, Gamma gamma, REGION, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Pion, High Energy Physics - Phenomenology (hep-ph), Pi, Bonn ELSA Stor, ddc:530, SPECTROMETER, NEAR-THRESHOLD, Nuclear Experiment (nucl-ex), Nuclear Experiment, AMPLITUDES, BARYON, Physics, N(2080), partial wave analysis, OPERATOR EXPANSION METHOD, Baryon, High Energy Physics - Phenomenology, Amplitude, exclusive reaction [photon p], angular dependence [differential cross section], STATES, High Energy Physics::Experiment, CROSS-SECTION, DECAY, small-angle, N(2070), experimental results, +2photon%22">pi0 --> 2photon
Abstract: Photoproduction of neutral pions has been studied with the CBELSA/TAPS detector in the reaction $\gamma p\to p\pi^0$ for photon energies between 0.85 and 2.50 GeV. The $\pi^0$ mesons are observed in their dominant neutral decay mode: $\pi^0\to\gamma\gamma$. For the first time, the differential cross sections cover the very forward region, $\theta_{\rm c.m.}, Comment: 12 pages, 9 figures, minor modifications to PWA section
Published: 2011
Full Text: View/download PDF

45. In-mediumωmass from theγ+Nb→π0γ+Xreaction

Author: V. Metag, M. Ostrick, M. Kotulla, Ch. Schmidt, A. Ehmanns, V. Crede, M. Pfeiffer, D. Elsner, R. Ewald, R. Bogendorfer, R. W. Novotny, Ph. Hoffmeister, Yu. A. Beloglazov, R. Gregor, T. Szczepanek, Friedrich Klein, B. Schoch, J. C. S. Bacelar, H. Schmieden, D. E. Bayadilov, I. Fabry, A. Radkov, A. B. Gridnev, Mariana Nanova, G. Suft, S. Shende, Michael Fuchs, D. Trnka, J. Langheinrich, J. Lotz, O. Bartholomy, H. Dutz, U. Thoma, Frank Klein, J. Hossl, S. Schadmand, R. Varma, I. V. Lopatin, R. W. Gothe, D. Walther, Ch. Weinheimer, H. van Pee, E. Gutz, J. Junkersfeld, J. G. Messchendorp, T. Mertens, Herbert Löhner, C. Morales, Lalit Mohan Pant, M. Konrad, B. Kopf, I. Jaegle, Gisela Anton, Ch. Funke, I. Horn, S. Lugert, Eberhard Klempt, S. Höffgen, B. Krusche, R. Castelijns, K. Essig, A. Süle, Ankhi Roy, D. Menze, Ch. Wendel, V. V. Sumachev, and H. Kalinowsky
Subjects: Absolute magnitude, Physics, Nuclear and High Energy Physics, Particle physics, Photon, Meson, Electron, Sensitivity (control systems), Nuclear Experiment, Nuclear matter, Omega, Line (formation)
Abstract: Data on the photoproduction of $\ensuremath{\omega}$ mesons on nuclei have been reanalyzed in a search for in-medium modifications. The data were taken with the crystal barrel (CB)/two-arm photon spectrometer (TAPS) detector system at the ELectron Stretcher Anlage (ELSA) accelerator facility in Bonn. First results from the analysis of the data set were published by Trnka et al. [Phys. Rev. Lett. 94, 192303 (2005)], claiming a lowering of the $\ensuremath{\omega}$ mass in the nuclear medium by 14$%$ at normal nuclear matter density. The extracted $\ensuremath{\omega}$ line shape was found to be sensitive to the background subtraction. For this reason a reanalysis of the same data set has been initiated, and a new method has been developed to reduce the background and to determine the shape and absolute magnitude of the background directly from the data. Details of the reanalysis and of the background determination are described. The $\ensuremath{\omega}$ signal on the Nb target, extracted in the reanalysis, does not show a deviation from the corresponding line shape on a ${\mathrm{LH}}_{2}$ target, measured as reference. The earlier claim of an in-medium mass shift is thus not confirmed. The sensitivity of the $\ensuremath{\omega}$ line shape to different in-medium modification scenarios is discussed.
Published: 2010
Full Text: View/download PDF

46. Measurement of the beam asymmetryΣin the forward direction forγ⃗p→pπ0

Author: O. Bartholomy, V. A. Nikonov, S. Lugert, Eberhard Klempt, H. Schmieden, D. E. Bayadilov, T. Mertens, E. Gutz, A. B. Gridnev, Mariana Nanova, Herbert Löhner, D. Elsner, R. Castelijns, Yu. A. Beloglazov, H. van Pee, H. Kalinowsky, J. C. S. Bacelar, A. V. Sarantsev, N. Sparks, R. W. Novotny, Ph. Hoffmeister, B. Krusche, D. Menze, Friedrich Klein, S. Kammer, I. Jaegle, C. Funke, Ch. Schmidt, Ch. Wendel, B. Schoch, V. V. Sumachev, L. M. Pant, A. Roy, R. Bantes, S. Shende, D. V. Novinski, V. Sokhoyan, Volker Metag, R. Gregor, A. V. Anisovich, U. Thoma, J. G. Messchendorp, D. Walther, S. Schadmand, J. Junkersfeld, R. Ewald, I. V. Lopatin, Wolfgang Hillert, R. Beck, D. Trnka, M. Kotulla, T. Szczepanek, R. Varma, A. Süle, M. Ostrick, V. Crede, Frank Klein, A. Wilson, M. Pfeiffer, and Frank Frommberger
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Photon, Meson, media_common.quotation_subject, Hadron, Sigma, Elementary particle, Asymmetry, Nuclear physics, Pion, High Energy Physics::Experiment, Nuclear Experiment, Lepton, media_common
Abstract: Photoproduction of neutral pions has been studied with the CBELSA/TAPS detector for photon energies between 0.92 and 1.68 GeV at the electron stretcher accelerator ELSA. The beam asymmetry Sigma has been extracted for 115 degrees > theta(c.m.) > 155 degrees of the pi(0) meson and for theta(c.m.) > 60 degrees. The new beam-asymmetry data cover the very forward region, which extend previously published data for the same reaction by our collaboration and improve the world database for photon energies above 1.5 GeV. The angular dependence of Sigma shows overall good agreement with the SAID parametrization.
Published: 2010
Full Text: View/download PDF

47. Photoproduction ofηandη'mesons off protons

Author: V. Crede, A. McVeigh, A. V. Anisovich, J. C. S. Bacelar, R. Bantes, O. Bartholomy, D. Bayadilov, R. Beck, Y. A. Beloglazov, R. Castelijns, A. Ehmanns, D. Elsner, K. Essig, R. Ewald, I. Fabry, M. Fuchs, Chr. Funke, R. Gothe, R. Gregor, A. Gridnev, E. Gutz, St. Höffgen, P. Hoffmeister, I. Horn, I. Jaegle, J. Junkersfeld, H. Kalinowsky, S. Kammer, Frank Klein, Friedrich Klein, E. Klempt, M. Konrad, M. Kotulla, B. Krusche, J. Langheinrich, H. Löhner, I. V. Lopatin, J. Lotz, S. Lugert, D. Menze, T. Mertens, J. G. Messchendorp, V. Metag, M. Nanova, V. A. Nikonov, D. Novinski, R. Novotny, M. Ostrick, L. M. Pant, H. van Pee, M. Pfeiffer, A. Roy, A. V. Sarantsev, S. Schadmand, C. Schmidt, H. Schmieden, B. Schoch, S. Shende, V. Sokhoyan, N. Sparks, A. Süle, V. V. Sumachev, T. Szczepanek, U. Thoma, D. Trnka, R. Varma, D. Walther, Ch. Weinheimer, Ch. Wendel, and A. Wilson
Subjects: Physics, Nuclear and High Energy Physics, Angular range, Particle physics, Photon, Meson, Proton, Nuclear Theory, Eta meson, Gamma gamma, Baryon, Nuclear physics, High Energy Physics::Experiment, Nuclear Experiment
Abstract: Total and differential cross sections for eta and eta(')photoproduction off the proton have been determined with the CBELSA/TAPS detector for photon energies between 0.85 and 2.55 GeV. The eta mesons are detected in their two neutral decay modes, eta ->gamma gamma and eta -> 3 pi(0)-> 6 gamma, and for the first time, cover the full angular range in cos theta(c.m.) of the eta meson. These new eta photoproduction data are consistent with the earlier CB-ELSA results. The eta(') mesons are observed in their neutral decay to pi(0)pi(0)eta -> 6 gamma and also extend the coverage in angular range.
Published: 2009
Full Text: View/download PDF

48. Beam asymmetries in near-thresholdωphotoproduction off the proton

Author: V. Sokhoyan, Matthew Lang, M. Pfeiffer, D. Walther, A. Ehmanns, J. Junkersfeld, R. Varma, Ch. Weinheimer, S. Shende, Friedrich Klein, M. Ostrick, H. Kalinowsky, H. Dutz, Frank Klein, A. Roy, R. Beck, D. Elsner, D. Menze, V. Metag, E. Gutz, V. Crede, Ph. Hoffmeister, H. Schmieden, I. Jaegle, D. E. Bayadilov, S. Kammer, A. B. Gridnev, H. van Pee, Mariana Nanova, Ch. Wendel, V. Kleber, Ch. Funke, Yu. A. Beloglazov, R. Castelijns, A. Suele, V. V. Sumachev, A. V. Sarantsev, O. Bartholomy, M. Kotulla, K. Essig, M. Konrad, D. Trnka, R. Novotny, S. Hoeffgen, I. V. Lopatin, T. Mertens, A. V. Anisovich, U. Thoma, Herbert Löhner, B. Bantes, C. Morales, B. Schoch, A. Radkov, J. G. Messchendorp, I. Fabry, J. C. S. Bacelar, R. Gregor, R. Ewald, T. Szczepanek, M. Fuchs, V. A. Nikonov, I. Horn, S. Lugert, Eberhard Klempt, Ch. Schmidt, J. Lotz, D. V. Novinski, B. Krusche, L. M. Pant, Research unit Nuclear & Hadron Physics, and Publica
Subjects: TAPS, Physics, Nuclear and High Energy Physics, Photon, Proton, Meson, media_common.quotation_subject, photon, Nuclear Theory, Bremsstrahlung, Resonance, PHOTONS, MESONS, ETA, Omega, Asymmetry, Nuclear physics, Pion, SPECTROMETER, High Energy Physics::Experiment, Atomic physics, Nuclear Experiment, media_common
Abstract: The photoproduction of {omega} mesons off protons has been studied at the Bonn ELSA accelerator from threshold to E{sub {gamma}}=1700 MeV. Linearly polarized beams were produced via coherent bremsstrahlung. Large photon asymmetries in excess of 50% were obtained. For the first time the pion asymmetries associated with the {omega}{yields}{pi}{sup 0}{gamma} decay were measured and found close to zero. The asymmetries indicate s-channel resonance formation on top of t-channel exchange processes.
Published: 2008
Full Text: View/download PDF

49. Quasifree photoproduction of eta mesons off the neutron

Author: T. Szczepanek, Ch. Weinheimer, B. Schoch, A.B. Gridnev, Herbert Löhner, C. Morales, A. Radkov, V. Metag, U. Thoma, M. Kotulla, D. V. Novinski, H. Dutz, T. Mertens, L.M. Pant, R. Varma, J. Junkersfeld, M. Ostrick, H. van Pee, V. A. Nikonov, R. Ewald, I. Fabry, M. Fuchs, D. Menze, A. Roy, O. Bartholomy, A. Ehmanns, M. Nanova, I. Horn, R. Beck, D. Elsner, J. Lotz, M. Konrad, B. Krusche, V. Sokhoyan, S. Schadmand, Frank Klein, D. Trnka, Eberhard Klempt, Ph. Hoffmeister, Ch. Funke, A. V. Sarantsev, S. Höffgen, R. Gregor, J. Langheinrich, J. C. S. Bacelar, Ch. Wendel, H. Schmieden, D. E. Bayadilov, S. Kammer, S. Lugert, B. Bantes, R. Novotny, K. Essig, M. Pfeiffer, Y.A. Beloglazov, A. Süle, H. Kalinowsky, A.V. Anisovich, R. W. Gothe, Ch. Schmidt, D. Walther, E. Gutz, V. V. Sumachev, Friedrich Klein, I. Jaegle, V. Kleber, S.V. Shende, R. Castelijns, M. Lang, J. G. Messchendorp, V. Crede, I. V. Lopatin, Publica, and KVI - Center for Advanced Radiation Technology
Subjects: Physics, Photon, Meson, Proton, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, NEAR-THRESHOLD PHOTOPRODUCTION, BEAM ASYMMETRY, General Physics and Astronomy, EXCLUSIVE MEASUREMENT, Photon energy, RESONANCE, PROTON, ELSA, DEUTERON, Nuclear physics, Recoil, Deuterium, S-11(1535), High Energy Physics::Experiment, Invariant mass, Neutron, SPECTROMETER, Nuclear Experiment, HE-4
Abstract: Precise data for quasi-free photoproduction of η-mesons off the deuteron have been measured at the Bonn ELSA accelerator with the combined Crystal Barrel/TAPS detector for incident photon energies up to 2.5GeV. The η-mesons have been detected in coincidence with recoil protons and neutrons. Possible nuclear effects like Fermi motion and re-scattering can be studied via a comparison of the quasi-free reaction off the bound proton to η-production off the free proton. No significant effects beyond the folding of the free cross-section with the momentum distribution of the bound protons have been found. These Fermi motion effects can be removed by an analysis using the invariant mass of the η-nucleon pairs reconstructed from the final-state four-momenta of the particles. The total cross-section for quasi-free η-photoproduction off the neutron reveals even without correction for Fermi motion a pronounced bump-like structure around 1GeV of incident photon energy, which is not observed for the proton. This structure is even narrower in the invariant-mass spectrum of the η-neutron pairs. Position and width of the peak in the invariant-mass spectrum are W ≈ 1665 MeV and FWHM Γ ≈ 25 MeV. The data are compared to the results of different models.
Published: 2008

50. Modification of the omega-meson lifetime in nuclear matter

Author: R. W. Novotny, Ph. Hoffmeister, B. Schoch, J. C. S. Bacelar, D. Menze, D. Elsner, R. Ewald, A. Radkov, T. Mertens, M. Kotulla, H. Dutz, B. Kopf, Ch. Wendel, A. Suele, V. V. Sumachev, D. Trnka, J. Langheinrich, I. Horn, T. Szczepanek, J. Hoessl, I. Jaegle, Gisela Anton, Fritz Klein, M. Ostrick, R. Castelijns, E. Gutz, Volker Metag, S. Lugert, S. Hoeffgen, R. W. Gothe, M. Fuchs, H. van Pee, Eberhard Klempt, K. Essig, Ch. Funke, J. Lotz, H. Kalinowsky, M. Konrad, V. Crede, B. Krusche, S. Shende, Frank Klein, Yu. A. Beloglazov, L. M. Pant, A. Ehmanns, Ch. Weinheimer, M. Pfeiffer, J. G. Messchendorp, O. Bartholomy, H. Schmieden, S. Schadmand, U. Mosel, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, Ch. Schmidt, I. V. Lopatin, G. Suft, R. Bogendoerfer, U. Thoma, D. Walther, P. Muehlich, R. Gregor, I. Fabry, J. Junkersfeld, A. Roy, H. Loehner, R. Varma, KVI - Center for Advanced Radiation Technology, and Publica
Subjects: TAPS, Particle physics, Meson, Nuclear Theory, Hadron, General Physics and Astronomy, Omega, Nuclear physics, ATTENUATION, QCD SUM-RULES, SPECTROMETER, Nuclear Experiment, Mass number, Physics, IN-MEDIUM, Nuclear matter, Omega baryon, Baryon, High Energy Physics - Phenomenology, PHOTON, High Energy Physics::Experiment, PHI-PHOTOPRODUCTION, Glauber, VECTOR-MESONS
Abstract: The photo production of $\omega$ mesons on the nuclei C, Ca, Nb and Pb has been measured using the Crystal Barrel/TAPS detector at the ELSA tagged photon facility in Bonn. The dependence of the $\omega$ meson cross section on the nuclear mass number has been compared with three different types of models, a Glauber analysis, a BUU analysis of the Giessen theory group and a calculation by the Valencia theory group. In all three cases, the inelastic $\omega$ width is found to be $130-150 \rm{MeV/c^2}$ at normal nuclear matter density for an average 3-momentum of 1.1 GeV/c. In the restframe of the $\omega$ meson, this inelastic $\omega$ width corresponds to a reduction of the $\omega$ lifetime by a factor $\approx 30$. For the first time, the momentum dependent $\omega$N cross section has been extracted from the experiment and is in the range of 70 mb., Comment: 5 pages, 4 figures
Published: 2007

Catalog

Books, media, physical & digital resources

See catalog results

Searchworks

Select search scope, currently: Articles Catalog books, media & more in Jio Institute collections Articles journal articles & other e-resources

Search

Search Constraints

Refine your results

Search Limiters

Topic

Publication Year Range

Language

Publication Type

Journal

Database

Publisher

64 results on '"Ch. Wendel"'

Search Results

Catalog

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources