Author: "Thoma, U" / Topic: nuclear theory - Searchworks@Jio Institute Digital Library Search Results

Your search keyword '"Thoma, U"' showing total 63 results

Start Over Author "Thoma, U" Topic nuclear theory

63 results on '"Thoma, U"'

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

Author: Metag, V., Nanova, M., Hartmann, J., Mahlberg, P., Afzal, F., Bartels, C., Bayadilov, D., Beck, R., Becker, M., Blanke, E., Brinkmann, K. -T., Ciupka, S., Crede, V., Dieterle, M., Dutz, H., Elsner, D., Frommberger, F., Gridnev, A., Gottschall, M., Grüner, M., Hammann, Ch., Hannappel, J., Hillert, W., Hoff, J., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kalinowsky, H., Kalischewski, F., Keshelashvili, I., Ketzer, B., Klassen, P., Klein, F., Koop, K., Kroenert, P., Krusche, B., Lang, M., Lopatin, I., Messi, F., Meyer, W., Mitlasóczky, B., Müller, J., Müllers, J., Nikonov, V., Novinsky, V., Novotny, R., Piontek, D., Reicherz, G., Richter, L., Rostomyan, T., Runkel, S., Salisbury, B., Sarantsev, A., Schaab, D., Schmidt, Ch., Schmieden, H., Schultes, J., Seifen, T., Sokhoyan, V., Sowa, C., Spieker, K., Stausberg, N., Thiel, A., Thoma, U., Triffterer, T., Urban, M., Urff, G., van Pee, H., Wagner, M., Walther, D., Wendel, Ch., Werthmüller, D., Wiedner, U., Wilson, A., Winnebeck, A., Witthauer, L., and Wunderlich, Y.
Subjects: Nuclear Experiment, Nuclear Theory
Abstract: The reaction $\gamma p \rightarrow p \pi^0 \eta$ has been studied with the CBELSA/TAPS detector at the electron stretcher accelerator ELSA in Bonn for incident photon energies from threshold up to 3.1 GeV. This paper has been motivated by the recently claimed observation of a narrow structure in the M$_{N\eta}$ invariant mass distribution at a mass of 1678 MeV/$c^2$. The existence of this structure cannot be confirmed in the present work. Instead, for E$_{\gamma}$ = 1400 - 1500 MeV and the cut M$_{p\pi^0} \le 1190 $ MeV/$c^2$ a statistically significant structure in the M$_{p\eta}$ invariant mass distribution near 1700 MeV/$c^2$ is observed with a width of $\Gamma\approx 35$ MeV/$c^2$ while the mass resolution is $\sigma_{res}$ = 5 MeV/$c^2$. Increasing the incident photon energy from 1420 to 1540 MeV this structure shifts in mass from $\approx$ 1700MeV/c$^2$ to $\approx$ 1725 MeV/$c^2$; the width increases to about 50 MeV/$c^2$ and decreases thereafter. The cross section associated with this structure reaches a maximum of $\approx$ 100 nb around E$_{\gamma} \approx$ 1490 MeV (W $\approx $ 1920 MeV), which coincides with the $p a_0$ threshold. Three scenarios are discussed which might be the origin of this structure in the M$_{p\eta}$ invariant mass distribution. The most likely interpretation is that it is due to a triangular singularity in the $\gamma p \rightarrow p a_0 \rightarrow p \pi^0 \eta$ reaction, Comment: 16 pages, 18 figure
Published: 2021
Full Text: View/download PDF

2. Hyperon I: Study of the $\Lambda(1405)$

Author: Anisovich, A. V., Sarantsev, A. V., Nikonov, V. A., Burkert, V., Schumacher, R. A., Thoma, U., and Klempt, E.
Subjects: Nuclear Experiment, Nuclear Theory
Abstract: Low-energy data on the three charge states in $\gamma p \to K^+(\Sigma\pi)$ from CLAS at JLab, on $K^-p\to \pi^0\pi^0\Lambda$ and $\pi^0\pi^0\Sigma$ from the Crystal Ball at BNL, bubble chamber data on $K^-p\to\pi^-\pi^+\pi^{\pm}\Sigma^{\mp}$, low-energy total cross sections on $K^-$ induced reactions, and data on the $K^-p$ atom are fitted with the BnGa partial-wave-analysis program. We find that the data can be fitted well with just one isoscalar spin-1/2 negative-parity pole, the $\Lambda(1405)$, and background contributions., Comment: 9 pages, 10 figures
Published: 2019

3. The Impact of New Polarization Data from Bonn, Mainz and Jefferson Laboratory on $\gamma p \to \pi N$ Multipoles

Author: Beck, A. V. Anisovich R., Döring, M., Gottschall, M., Hartmann, J., Kashevarov, V., Klempt, E., Meißner, Ulf-G., Nikonov, V., Ostrick, M., Rönchen, D., Sarantsev, A., Strakovsky, I., Thiel, A., Tiator, L., Thoma, U., Workman, R., and Wunderlich, Y.
Subjects: Nuclear Theory, Nuclear Experiment
Abstract: New data on pion-photoproduction off the proton have been included in the partial wave analyses Bonn-Gatchina and SAID and in the dynamical coupled-channel approach J\"ulich-Bonn. All reproduce the recent new data well: the double polarization data for E, G, H, P and T in $\gamma p \to \pi^0 p$ from ELSA, the beam asymmetry $\Sigma$ for $\gamma p \to \pi^0 p$ and $\pi^+ n$ from Jefferson Laboratory, and the precise new differential cross section and beam asymmetry data $\Sigma$ for $\gamma p \to \pi^0 p$ from MAMI. The new fit results for the multipoles are compared with predictions not taking into account the new data. The mutual agreement is improved considerably but still far from being perfect.
Published: 2016

4. Evidence for $\Delta(2200)7/2^-$ from photoproduction and consequence for chiral-symmetry restoration at high mass

Author: Anisovich, A. V., Burkert, V., Hartmann, J., Klempt, E., Nikonov, V. A., Pasyuk, E., Sarantsev, A. V., Strauch, S., and Thoma, U.
Subjects: Nuclear Experiment, Nuclear Theory
Abstract: We report a partial-wave analysis of new data on the double-polarization variable $E$ for the reactions $\gamma p\to \pi^+ n$ and $\gamma p\to \pi^0 p$ and of further data published earlier. The analysis within the Bonn-Gatchina (BnGa) formalism reveals evidence for a poorly known baryon resonance, the one-star $\Delta(2200)7/2^-$. This is the lowest-mass $\Delta^*$ resonance with spin-parity $J^P=7/2^-$. Its mass is significantly higher than the mass of its parity partner $\Delta(1950)7/2^+$ which is the lowest-mass $\Delta^*$ resonance with spin-parity $J^P=7/2^+$. It has been suggested that chiral symmetry might be restored in the high-mass region of hadron excitations, and that these two resonances should be degenerate in mass. Our findings are in conflict with this prediction., Comment: 5 pages, 3 figures; Physics Letters B in press
Published: 2015

5. Energy-independent PWA of the reaction $\gamma p\to K^+\Lambda$

Author: Anisovich, A. V., Beck, R., Burkert, V., Klempt, E., McCracken, M. E., Nikonov, V. A., Sarantsev, A. V., Schumacher, R. A., and Thoma, U.
Subjects: Nuclear Experiment, Nuclear Theory
Abstract: Using all recent data on the differential cross sections and spin observables for the reaction $\gamma p \to K^+ \Lambda$, an energy-independent partial-wave analysis is performed. The analysis requires multipoles up to $L = 2$; there is no evidence that the fit requires multipoles with $L=3$. At present the available data allow us to extract the dominant multipoles only. These are compatible with the multipoles obtained in the energy-dependent fit. This result supports the reliability of the Bonn-Gatchina energy-dependent results., Comment: 9 pages, 3 figures
Published: 2014
Full Text: View/download PDF

6. Sign ambiguity in the K Sigma channel

Author: Anisovich, A. V., Klempt, E., Nikonov, V. A., Sarantsev, A. V., and Thoma, U.
Subjects: Nuclear Experiment, Nuclear Theory
Abstract: Ambiguities of the signs of $N\to \Sigma K$ coupling constants are studied in a multichannel partial wave analysis of a large body of pion and photo-induced reactions. It is shown that the signs are not free from some ambiguities, and further experimental data are needed. Data on the reactions $\pi^+p\to \Sigma^+K^+$ and $\gamma p\to K^+\Sigma^0$ define rather well the isospin 3/2 contributions to these channels. However the lack of information on polarization observables for the reactions $\pi^-p\to \Sigma^0K^0$, $\pi^-p\to \Sigma^-K^+$ and $\gamma p\to K^0\Sigma^+$ does not allow us to fix uniquely the signs of $N\to \Sigma K$ coupling constants. As a consequence, also the contributions of nucleon resonances to these channels remain uncertain., Comment: 8 pages, 12 figures
Published: 2013
Full Text: View/download PDF

7. Pion- and photo-induced transition amplitudes to $\Lambda K$, $\Sigma K$, and $N\eta$

Author: Anisovich, A. V., Beck, R., Klempt, E., Nikonov, V. A., Sarantsev, A. V., and Thoma, U.
Subjects: Nuclear Theory
Abstract: Pion and photo-induced inelastic reactions off protons are studied in a multichannel partial-wave analysis. Properties of nucleon and $\Delta$ resonances are derived and compared to previous analyses. Amplitudes are shown for transitions to $N\eta$, $\Lambda K$, and $\Sigma K$ final states., Comment: 9 pages, 6 figures
Published: 2012
Full Text: View/download PDF

8. Search for Narrow Nucleon Resonance in $\gamma p\to \eta p$

Author: Anisovich, A. V., Klempt, E., Kuznetsov, V., Nikonov, V. A., Polyakov, M. V., Sarantsev, A. V., and Thoma, U.
Subjects: High Energy Physics - Phenomenology, High Energy Physics - Experiment, Nuclear Experiment, Nuclear Theory
Abstract: Results of a partial wave analysis of new high-statistics data on $\gamma p\to p\eta$ from MAMI are presented. A fit using known broad resonances and only standard background amplitudes can not describe the relatively narrow peaking structure in the cross section in the mass region of 1660-1750 MeV which follows a minimum. An improved description of the data can be reached by either assuming the existence of a narrow resonance at a mass of about 1700 MeV with small photo-coupling or by a threshold effect. In the latter case the observed structure is explained by a strong (resonant or non-resonant) $\gamma p\to\omega p$ coupling in the $S_{11}$ partial wave. When the beam asymmetry data, published by part of the GRAAL collaboration, are included in the fit, the solution with a narrow $P_{11}$ state is slightly preferred. In that fit, mass and width of the hypothetical resonance are determined to $M\sim$1694 MeV and $\Gamma\sim 40$ MeV, respectively, and the photo-coupling to $\sqrt{{\rm Br}_{\eta N}} A_{1/2}^p \sim 2.6\cdot 10^{-3}$ GeV$^{-1/2}$. High precision measurements of the target asymmetry and $F$-observable are mandatory to establish the possible existence of such a narrow state and to provide the necessary information to define which partial wave is responsible for the structure observed in the data., Comment: 6 pages, 5 figures
Published: 2011

9. Modification of the $\omega$-Meson Lifetime in Nuclear Matter

Author: Kotulla, M., Trnka, D., Mühlich, P., Anton, G., Bacelar, J. C. S., Bartholomy, O., Bayadilov, D., Beloglazov, Y. A., Bogendörfer, R., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Ewald, R., Fabry, I., Fuchs, M., Essig, K., Funke, Ch., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Höffgen, S., Hoffmeister, P., Horn, I., Hössl, J., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Klein, Frank, Klein, Fritz, Klempt, E., Konrad, M., Kopf, B., Krusche, B., Langheinrich, J., Löhner, H., Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Messchendorp, J. G., Mertens, T., Metag, V., Mosel, U., Nanova, M., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Roy, A., Radkov, A., Schadmand, S., Schmidt, Ch., Schmieden, H., Schoch, B., Shende, S., Suft, G., Sumachev, V. V., Szczepanek, T., Süle, A., Thoma, U., Varma, R., Walther, D., Weinheimer, Ch., and Wendel, Ch.
Subjects: Nuclear Experiment, High Energy Physics - Phenomenology, Nuclear Theory
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: 2008
Full Text: View/download PDF

10. Observation of a structure in the M$_{p��}$ invariant mass distribution near 1700 MeV/$c^2$ in the $\mathbf{��p \rightarrow p ��^0 ��} $ reaction

Author: Metag, V., Nanova, M., Hartmann, J., Mahlberg, P., Afzal, F., Bartels, C., Bayadilov, D., Beck, R., Becker, M., Blanke, E., Brinkmann, K. -T., Ciupka, S., Crede, V., Dieterle, M., Dutz, H., Elsner, D., Frommberger, F., Gridnev, A., Gottschall, M., Gr��ner, M., Hammann, Ch., Hannappel, J., Hillert, W., Hoff, J., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kalinowsky, H., Kalischewski, F., Keshelashvili, I., Ketzer, B., Klassen, P., Klein, F., Koop, K., Kroenert, P., Krusche, B., Lang, M., Lopatin, I., Messi, F., Meyer, W., Mitlas��czky, B., M��ller, J., M��llers, J., Nikonov, V., Novinsky, V., Novotny, R., Piontek, D., Reicherz, G., Richter, L., Rostomyan, T., Runkel, S., Salisbury, B., Sarantsev, A., Schaab, D., Schmidt, Ch., Schmieden, H., Schultes, J., Seifen, T., Sokhoyan, V., Sowa, C., Spieker, K., Stausberg, N., Thiel, A., Thoma, U., Triffterer, T., Urban, M., Urff, G., van Pee, H., Wagner, M., Walther, D., Wendel, Ch., Werthm��ller, D., Wiedner, U., Wilson, A., Winnebeck, A., Witthauer, L., and Wunderlich, Y.
Subjects: Nuclear Theory (nucl-th), Nuclear Theory, Physics::Accelerator Physics, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: The reaction $��p \rightarrow p ��^0 ��$ has been studied with the CBELSA/TAPS detector at the electron stretcher accelerator ELSA in Bonn for incident photon energies from threshold up to 3.1 GeV. This paper has been motivated by the recently claimed observation of a narrow structure in the M$_{N��}$ invariant mass distribution at a mass of 1678 MeV/$c^2$. The existence of this structure cannot be confirmed in the present work. Instead, for E$_��$ = 1400 - 1500 MeV and the cut M$_{p��^0} \le 1190 $ MeV/$c^2$ a statistically significant structure in the M$_{p��}$ invariant mass distribution near 1700 MeV/$c^2$ is observed with a width of $��\approx 35$ MeV/$c^2$ while the mass resolution is $��_{res}$ = 5 MeV/$c^2$. Increasing the incident photon energy from 1420 to 1540 MeV this structure shifts in mass from $\approx$ 1700MeV/c$^2$ to $\approx$ 1725 MeV/$c^2$; the width increases to about 50 MeV/$c^2$ and decreases thereafter. The cross section associated with this structure reaches a maximum of $\approx$ 100 nb around E$_�� \approx$ 1490 MeV (W $\approx $ 1920 MeV), which coincides with the $p a_0$ threshold. Three scenarios are discussed which might be the origin of this structure in the M$_{p��}$ invariant mass distribution. The most likely interpretation is that it is due to a triangular singularity in the $��p \rightarrow p a_0 \rightarrow p ��^0 ��$ reaction, 16 pages, 18 figure
Published: 2021
Full Text: View/download PDF

11. New data on $\vec{\gamma} \vec{p}\rightarrow \eta p$ with polarized photons and protons and their implications for $N^* \to N\eta$ decays

Author: Müller, J., Hartmann, J., Grüner, M., Afzal, F., Anisovich, A. V., Bantes, B., Bayadilov, D., Beck, R., Becker, M., Beloglazov, Y., Berlin, M., Bichow, M., Böse, S., Brinkmann, K. -T., Challand, T., Crede, V., Dietz, F., Dieterle, M., Drexler, P., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, S., Frommberger, F., Funke, C., Gottschall, M., Gridnev, A., Goertz, S., Gutz, E., Hammann, C., Hannen, V., Hannappel, J., Herick, J., Hillert, W., Hoffmeister, P., Honisch, C., Jahn, O., Jude, T., Jaegle, I., Käser, A., Kaiser, D., Kalinowsky, H., Kalischewski, F., Kammer, S., Keshelashvili, I., Klassen, P., Kleber, V., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Maghrbi, Y., Mahlberg, P., Makonyi, K., Messi, F., Metag, V., Meyer, W., Müllers, J., Nanova, M., Nikonov, V., Novinski, D., Novotny, R., Piontek, D., Reicherz, G., Rosenbaum, C., Rostomyan, T., Roth, B., Sarantsev, A., Schmidt, C., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, C., Wiedner, U., Wilson, A., Winnebeck, A., Witthauer, L., and Collaboration, CBELSA/TAPS
Subjects: Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract: The polarization observables $T, E, P, H$, and $G$ in photoproduction of $\eta$ 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, J\"uBo, and BnGa partial-wave analyses. A refit within the BnGa approach including further data yields precise branching ratios for the $N\eta$ decay of nucleon resonances. A $N\eta$-branching ratio of $0.33\pm 0.04$ for $N(1650)1/2^-$ is found, which reduces the large and controversially discussed $N\eta$-branching ratio difference of the two lowest mass $J^P=1/2^-$-resonances significantly., Comment: 10 pages, 11 figures
Published: 2019

12. Measurement of the Helicity Asymmetry $E$ for the reaction $ \gamma p\to \pi^0 p$

Author: collaboration, CBELSA/TAPS, Gottschall, M., Afzal, F., Anisovich, A. V., Bayadilov, D., Beck, R., Bichow, M., Brinkmann, K. -Th., Crede, V., Dieterle, M., Dietz, F., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Gridnev, A., Grüner, M., Gutz, E., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kammer, S., Kalinowsky, H., Keshelashvili, I., Klassen, P., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Mahlberg, P., Makonyi, K., Metag, V., Meyer, W., Müller, J., Müllers, J., Nanova, M., Nikonov, V., Novotny, R., Piontek, D., Reicherz, G., Rostomyan, T., Sarantsev, A., Schmidt, Ch., Schmieden, H., Seifen, T., Sokhoyan, V., Spieker, K., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Werthmüller, D., Wiedner, U., Wilson, A., Winnebeck, A., Witthauer, L., and Wunderlich, Y.
Subjects: Nuclear Theory, Physics::Accelerator Physics, Nuclear Experiment
Abstract: A measurement of the double-polarization observable $E$ for the reaction $\gamma p\to \pi^0 p$ is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C$_4$H$_9$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 $E_\gamma =600$~MeV to $E_\gamma =2310$~MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses., Comment: 21 pages
Published: 2019

13. Technical Design Report for the PANDA Barrel DIRC Detector

Author: Singh, B., Erni, W., Zhao, J., Deppe, H., Veis, N Divani, Dzhygadlo, R., Flemming, H., Gerhardt, A., Götzen, K., Gromliuk, A., Gruber, L., Hohler, R., Kalicy, G., Albrecht, M., Karabowicz, R., Kliemt, R., Krebs, M., Kurilla, U., Lehmann, D., Löchner, S., Lühning, J., Lynen, U., Nerling, F., Orth, H., Erlen, T., Patsyuk, M., Peters, K., Saito, T., Schepers, G., Schmidt, C. J., Schwarz, C., Schwiening, J., Täschner, A., Traxler, M., Ugur, C., Feldbauer, F., Voss, B., Wieczorek, P., Wilms, A., Zühlsdorf, M., Abazov, V., Alexeev, G., Arefiev, V. A., Astakhov, V., Barabanov, M Yu, Batyunya, B. V., Fink, M., Davydov, Y., Dodokhov, V Kh, Efremov, A., Fechtchenko, A., Fedunov, A. G., Galoyan, A., Grigoryan, S., Koshurnikov, E. K., Lobanov, Y Yu, Lobanov, V. I., Fritsch, M., Makarov, A. F., Malinina, L. V., Malyshev, V., Olshevskiy, A. G., Perevalova, E., Piskun, A. A., Pocheptsov, T., Pontecorvo, G., Rodionov, V., Rogov, Y., Haase, J., Salmin, R., Samartsev, A., Sapozhnikov, M. G., Shabratova, G., Skachkov, N. B., Skachkova, A. N., Strokovsky, E. A., Suleimanov, M., Teshev, R., Tokmenin, V., Heinsius, F. H., Uzhinsky, V., Vodopianov, A., Zaporozhets, S. A., Zhuravlev, N. I., Zinchenko, A., Branford, D., Glazier, D., Watts, D., Böhm, M., Britting, A., Held, T., Eyrich, W., Lehmann, A., Pfaffinger, M., Uhlig, F., Dobbs, S., Seth, K., Tomaradze, A., Xiao, T., Bettoni, D., Carassiti, V., Holtmann, T., Ramusino, A Cotta, Dalpiaz, P., Drago, A., Fioravanti, E., Garzia, I., Savrie, M., Akishina, V., Gorbunov, S., Kisel, I., Kozlov, G., Krusche, B., Keshk, I., Pugach, M., Zyzak, M., Gianotti, P., Guaraldo, C., Lucherini, V., Bersani, A., Bracco, G., Macri, M., Parodi, R. F., Biguenko, K., Koch, H., Brinkmann, K. T., Pietro, V Di, Diehl, S., Dormenev, V., Düren, M., Etzelmüller, E., Föhl, K., Galuska, M., Gutz, E., Hahn, C., Kopf, B., Hayrapetyan, A., Kesselkaul, M., Kreutzfeldt, K., Kühn, W., Kuske, T., Lange, J. S., Liang, Y., Metag, V., Moritz, M., Nanova, M., Kuhlmann, M., Novotny, R., Quagli, T., Reiter, S., Riccardi, A., Rieke, J., Rosenbaum, C., Schmidt, M., Schnell, R., Stenzel, H., Thöring, U., Kümmel, M., Wagner, M. N., Wasem, T., Wohlfahrt, B., Zaunick, H. G., Tomasi-Gustafsson, E., Ireland, D., Rosner, G., Seitz, B., Deepak, P. N., Kulkarni, A., Leiber, S., Apostolou, A., Babai, M., Kavatsyuk, M., Lemmens, P. J., Lindemulder, M., Loehner, H., Messchendorp, J., Schakel, P., Smit, H., Tiemens, M., Mikirtychyants, M., Weele, J C van der, Veenstra, R., Vejdani, S., Dutta, K., Kalita, K., Kumar, A., Roy, A., Sohlbach, H., Bai, M., Musiol, P., Bianchi, L., Büscher, M., Cao, L., Cebulla, A., Dosdall, R., Erven, A., Fracassi, V., Gillitzer, A., Goldenbaum, F., Grunwald, D., Mustafa, A., Herten, A., Hu, Q., Jokhovets, L., Kemmerling, G., Kleines, H., Lai, A., Lehrach, A., Nellen, R., Ohm, H., Orfanitski, S., Pelizäus, M., Prasuhn, D., Prencipe, E., Pütz, J., Ritman, J., Rosenthal, E., Schadmand, S., Sefzick, T., Serdyuk, V., Sterzenbach, G., Stockmanns, T., Steinacher, M., Pitka, A., Wintz, P., Wüstner, P., Xu, H., Li, S., Li, Z., Sun, Z., Rigato, V., Isaksson, L., Achenbach, P., Pychy, J., Aycock, A., Corell, O., Denig, A., Distler, M., Hoek, M., Karavdina, A., Lauth, W., Liu, Z., Merkel, H., Müller, U., Richter, M., Pochodzalla, J., Sanchez, S., Schlimme, S., Sfienti, C., Thiel, M., Ahmadi, H., Ahmed, S., Bleser, S., Capozza, L., Cardinali, M., Schnier, C., Dbeyssi, A., Deiseroth, M., Ehret, A., Fröhlich, B., Kang, D., Khaneft, D., Klasen, R., Leithoff, H. H., Lin, D., Maas, F., Schröder, T., Maldaner, S., Martínez, M., Michel, M., Mora Espí, M. C., Morales, C Morales, Motzko, C., Noll, O., Pflüger, S., Rodríguez Piñeiro, D., Sanchez-Lorente, A., Sowa, C., Steinen, M., Valente, R., Zambrana, M., Zimmermann, I., Fedorov, A., Korjik, M., Missevitch, O., Balashoff, A., Boukharov, A., Malyshev, O., Steinke, M., Marishev, I., Balanutsa, P., Balanutsa, V., Chernetsky, V., Demekhin, A., Dolgolenko, A., Fedorets, P., Gerasimov, A., Goryachev, V., Chandratre, V., Triffterer, T., Datar, V., Dutta, D., Jha, V., Kumawat, H., Mohanty, A. K., Parmar, A., Rai, A. K., Roy, B., Sonika, G., Fritzsch, C., Wiedner, U., Grieser, S., Hergemöller, A. K., Hetz, B., Hüsken, N., Khoukaz, A., Wessels, J. P., Khosonthongkee, K., Kobdaj, C., Limphirat, A., Srisawad, P., Ball, M., Yan, Y., Antokhin, E., Barnyakov, A Yu, Barnyakov, M., Beloborodov, K., Blinov, V. E., Bobrovnikov, V. S., Kuyanov, I. A., Martin, K., Onuchin, A. P., Walford, N., Beck, R., Pivovarov, S., Pyata, E., Serednyakov, S., Sokolov, A., Tikhonov, Y., Blinov, A. E., Kononov, S., Kravchenko, E. A., Atomssa, E., Kunne, R., Hammann, C., Marchand, D., Ramstein, B., Wiele, J van de, Wang, Y., Boca, G., Costanza, S., Genova, P., Montagna, P., Rotondi, A., Bodlak, M., Ketzer, B., Finger, M., Nikolovova, A., Pesek, M., Peskova, M., Pfeffer, M., Prochazka, I., Slunecka, M., Gallus, P., Jary, V., Kube, M., Novy, J., Tomasek, M., Virius, M., Vrba, V., Abramov, V., Belikov, N., Bukreeva, S., Davidenko, A., Derevschikov, A., Goncharenko, Y., Mahlberg, P., Grishin, V., Kachanov, V., Kormilitsin, V., Levin, A., Melnik, Y., Minaev, N., Mochalov, V., Morozov, D., Nogach, L., Poslavskiy, S., Rossbach, M., Ryazantsev, A., Ryzhikov, S., Semenov, P., Shein, I., Uzunian, A., Vasiliev, A., Yakutin, A., Roy, U., Yabsley, B., Belostotski, S., Schmidt, C., Gavrilov, G., Izotov, A., Manaenkov, S., Miklukho, O., Veretennikov, D., Zhdanov, A., Makonyi, K., Preston, M., Tegner, P. E., Wölbing, D., Schmitz, R., Bäck, T., Cederwall, B., Godre, S., Balestra, F., Iazzi, F., Introzzi, R., Lavagno, A., Olave, J., Amoroso, A., Bussa, M. P., Thoma, U., Busso, L., Destefanis, M., Fava, L., Ferrero, L., Greco, M., Hu, J., Lavezzi, L., Maggiora, M., Maniscalco, G., Marcello, S., Urban, M., Sosio, S., Spataro, S., Calvo, D., Coli, S., Remigis, P De, Filippi, A., Giraudo, G., Lusso, S., Mazza, G., Mignone, M., Liu, B., Walther, D., Rivetti, A., Wheadon, R., Birsa, R., Bradamante, F., Bressan, A., Martin, A., Calen, H., Andersson, W Ikegami, Johansson, T., Kupsc, A., Wendel, C., Marciniewski, P., Papenbrock, M., Pettersson, J., Schönning, K., Wolke, M., Galnander, B., Diaz, J., Chackara, V Pothodi, Chlopik, A., Kesik, G., Wilson, A., Melnychuk, D., Slowinski, B., Trzcinski, A., Wojciechowski, M., Wronka, S., Zwieglinski, B., Bühler, P., Marton, J., Steinschaden, D., Suzuki, K., Bianconi, A., Widmann, E., Zimmermann, S., Zmeskal, J., Bragadireanu, M., Pantea, D., Patel, B., Czyzycki, W., Domagala, M., Filo, G., Liu, H., Jaworowski, J., Krawczyk, M., Lisowski, E., Lisowski, F., Michałek, M., Poznański, P., Płażek, J., Korcyl, K., Kozela, A., Kulessa, P., Lebiedowicz, P., Pysz, K., Schäfer, W., Szczurek, A., Fiutowski, T., Idzik, M., Mindur, B., Swientek, K., Biernat, J., Kamys, B., Shen, X., Kistryn, S., Korcyl, G., Krzemien, W., Magiera, A., Moskal, P., Pyszniak, A., Rudy, Z., Salabura, P., Smyrski, J., Strzempek, P., Wang, C., Wronska, A., Augustin, I., Böhm, R., Lehmann, I., Marinescu, D Nicmorus, Schmitt, L., Varentsov, V., Ali, A., Al-Turany, M., Belias, A., Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), PANDA, and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)
Subjects: Physics - Instrumentation and Detectors, Physics::Instrumentation and Detectors, Nuclear Theory, FOS: Physical sciences, costs, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], DIRC, NO, High Energy Physics - Experiment, K: particle identification, High Energy Physics - Experiment (hep-ex), Experiment, hadron physics, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], ddc:530, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], High Energy Physics, Nuclear Experiment (nucl-ex), numerical calculations, Nuclear Experiment, activity report, Cherenkov counter: design, DIRC counter, PANDA experiment, particle identification, ring imaging Cherenkov detector, PANDA, Physics, Instrumentation and Detectors (physics.ins-det), Physics, Instrumentation and Detectors, Physics, Instrumentation and Detectors, High Energy Physics, Experiment, Nuclear Experiment, High Energy Physics::Experiment, pi: particle identification, performance, Instrumentation and Detectors, acceptance
Abstract: The PANDA (anti-Proton ANnihiliation at DArmstadt) experiment will be one ofthe four flagship experiments at the new international accelerator complex FAIR(Facility for Antiproton and Ion Research) in Darmstadt, Germany. PANDA willaddress fundamental questions of hadron physics and quantum chromodynamicsusing high-intensity cooled antiproton beams with momenta between 1.5 and15 GeV/c and a design luminosity of up to 2× 10^32 cm−2 s−1. Excellent particleidentification (PID) is crucial to the success of the PANDA physics program.Hadronic PID in the barrel region of the target spectrometer will be performed by afast and compact Cherenkov counter using the detection of internally reflectedCherenkov light (DIRC) technology. It is designed to cover the polar angle rangefrom 22° to 140° and will provide at least 3 standard deviations (s.d.) π/Kseparation up to 3.5GeV/c, matching the expected upper limit of the final statekaon momentum distribution from simulation. This documents describes thetechnical design and the expected performance of the PANDA Barrel DIRCdetector. The design is based on the successful BaBar DIRC with several keyimprovements. The performance and system cost were optimized in detaileddetector simulations and validated with full system prototypes using particle beamsat GSI and CERN. The final design meets or exceeds the PID goal of clean π/Kseparation with at least 3 s.d. over the entire phase space of charged kaons in theBarrel DIRC.
Published: 2019

14. Measurement of the Helicity Asymmetry $E$ for the reaction $ ��p\to ��^0 p$

Author: TAPS Collaboration, Gottschall, M., Afzal, F., Anisovich, A. V., Bayadilov, D., Beck, R., Bichow, M., Brinkmann, K. -Th., Crede, V., Dieterle, M., Dietz, F., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Gridnev, A., Gr��ner, M., Gutz, E., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kammer, S., Kalinowsky, H., Keshelashvili, I., Klassen, P., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Mahlberg, P., Makonyi, K., Metag, V., Meyer, W., M��ller, J., M��llers, J., Nanova, M., Nikonov, V., Novotny, R., Piontek, D., Reicherz, G., Rostomyan, T., Sarantsev, A., Schmidt, Ch., Schmieden, H., Seifen, T., Sokhoyan, V., Spieker, K., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Werthm��ller, D., Wiedner, U., Wilson, A., Winnebeck, A., Witthauer, L., and Wunderlich, Y.
Subjects: Nuclear Theory, Physics::Accelerator Physics, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: A measurement of the double-polarization observable $E$ for the reaction $��p\to ��^0 p$ is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C$_4$H$_9$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 $E_��=600$~MeV to $E_��=2310$~MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses., 21 pages
Published: 2019
Full Text: View/download PDF

15. New data on $\vec�� \vec{p}\rightarrow ��p$ with polarized photons and protons and their implications for $N^* \to N��$ decays

Author: M��ller, J., Hartmann, J., Gr��ner, M., Afzal, F., Anisovich, A. V., Bantes, B., Bayadilov, D., Beck, R., Becker, M., Beloglazov, Y., Berlin, M., Bichow, M., B��se, S., Brinkmann, K. -T., Challand, T., Crede, V., Dietz, F., Dieterle, M., Drexler, P., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, S., Frommberger, F., Funke, C., Gottschall, M., Gridnev, A., Goertz, S., Gutz, E., Hammann, C., Hannen, V., Hannappel, J., Herick, J., Hillert, W., Hoffmeister, P., Honisch, C., Jahn, O., Jude, T., Jaegle, I., K��ser, A., Kaiser, D., Kalinowsky, H., Kalischewski, F., Kammer, S., Keshelashvili, I., Klassen, P., Kleber, V., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Maghrbi, Y., Mahlberg, P., Makonyi, K., Messi, F., Metag, V., Meyer, W., M��llers, J., Nanova, M., Nikonov, V., Novinski, D., Novotny, R., Piontek, D., Reicherz, G., Rosenbaum, C., Rostomyan, T., Roth, B., Sarantsev, A., Schmidt, C., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, C., Wiedner, U., Wilson, A., Winnebeck, A., Witthauer, L., and Collaboration, CBELSA/TAPS
Subjects: Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: The polarization observables $T, E, P, H$, and $G$ in photoproduction of $��$ 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, J��Bo, and BnGa partial-wave analyses. A refit within the BnGa approach including further data yields precise branching ratios for the $N��$ decay of nucleon resonances. A $N��$-branching ratio of $0.33\pm 0.04$ for $N(1650)1/2^-$ is found, which reduces the large and controversially discussed $N��$-branching ratio difference of the two lowest mass $J^P=1/2^-$-resonances significantly., 10 pages, 11 figures
Published: 2019
Full Text: View/download PDF

16. Quasi-free photoproduction of η -mesons off the deuteron

Author: Jaegle, I., Krusche, B., Anisovich, A., Bacelar, J., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y., Castelijns, R., Crede, V., Dieterle, M., Dutz, H., Elsner, D., Ewald, R., Frommberger, F., Funke, C., Gothe, R., Gregor, R., Gridnev, A., Gutz, E., Hillert, W., Höffgen, S., Hoffmeister, P., Horn, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Keshelashvili, I., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kotulla, M., Lang, M., Löhner, H., Lopatin, I., Lugert, S., Maghrbi, Y., Menze, D., Mertens, T., Messchendorp, J., Metag, V., Nikonov, V., Nanova, M., Novinski, D., Novotny, R., Oberle, M., Ostrick, M., Pant, L., van Pee, H., Pfeiffer, M., Pheron, F., Roy, A., Sarantsev, A., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Sokhoyan, V., Süle, A., Sumachev, V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Wendel, C., Werthmüller, D., and Witthauer, L.
Subjects: Nuclear Theory, Nuclear Experiment
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: 2018

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

Author: Nanova, M., Friedrich, S., Brinkmann, K. -T., Crede, V., Drexler, P., Eberhardt, H., Elsner, D., Frommberger, F., Funke, Ch., Gottschall, M., Grüner, M., Gutz, E., Metag, V., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kaiser, D., Kalischewski, F., Keshelashvili, I., Paryev, E. Ya., Klein, F., Koop, K., Krusche, B., Lang, M., Makonyi, K., Messi, F., Müller, J., Müllers, J., Piontek, D., Rostomyan, T., Afzal, F. N., Schaab, D., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Sowa, C., Spieker, K., Thiel, A., Thoma, U., Bayadilov, D., Triffterer, T., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Werthmüller, D., Wiedner, U., Wilson, A., Witthauer, L., Wunderlich, Y., Bantes, B., Zaunick, H. -G., Beck, R., Becker, M., and Böse, S.
Subjects: Nuclear Theory, High Energy Physics::Experiment, ddc:530, Nuclear Experiment
Abstract: The production of η′ 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 η′ mesons have been identified via the η′→π0π0η→6γ decay registered with the CBELSA/TAPS detector system. Coincident protons have been identified in the MiniTAPS BaF2 array at polar angles of 2∘≤θp≤11∘. Under these kinematic constraints the η′ mesons are produced with relatively low kinetic energy (≈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 η′-carbon potential at low meson momenta by comparing with collision model calculations of the η′ kinetic energy distribution and excitation function. Fitting the latter data for η′ mesons going backwards in the center-of-mass system yields a potential depth of V=−(44±16(stat)±15(syst)) MeV, consistent with earlier determinations of the potential depth in inclusive measurements for average η′ momenta of ≈1.1 GeV/c. Within the experimental uncertainties, there is no indication of a momentum dependence of the η′-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 η′ photoproduction off the free proton.
Published: 2018

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

Author: Ewald, R., Anisovich, A.V., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y.A., Brinkmann, K.-T., Crede, V., Dutz, H., Elsner, D., Fornet-Ponse, K., Frommberger, F., Funke, Ch., Gridnev, A.B., Gutz, E., Hannappel, J., Hillert, W., Hoffmeister, P., Jaegle, I., Jahn, O., Jude, T.C., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Krusche, B., Lang, M., Löhner, H., Lopatin, I.V., Menze, D., Mertens, T., Messchendorp, J.G., Metag, V., Nanova, M., Nikonov, V.A., Novinski, D., Novotny, R., Ostrick, M., Pant, L., van Pee, H., Roy, A., Sarantsev, A.V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Sokhoyan, V., Süle, A., Sumachev, V.V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., and Wendel, Ch.
Subjects: Polarisation in interactions and scattering, Nuclear Theory, Meson production, High Energy Physics::Experiment, Decays of baryons, Other strange mesons, Nuclear Experiment, lcsh:Physics, lcsh:QC1-999, Baryon resonances (SCB0)
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

19. Momentum dependence of the imaginary part of the ω - and η -nucleus optical potential

Author: Friedrich, S., Nanova, M., Metag, V., Afzal, F. N., Bayadilov, D., Bantes, B., Beck, R., Becker, M., Böse, S., Brinkmann, K. T., Crede, V., Drexler, P., Eberhardt, H., Elsner, D., Frommberger, F., Funke, Ch, Gottschall, M., Grüner, M., Gutz, E., Hammann, Ch, Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph, Honisch, Ch, Jude, T., Kaiser, D., Kalischewski, F., Keshelashvili, I., Klein, F., Koop, K., Krusche, B., Makonyi, K., Messi, F., Müller, J., Müllers, J., Piontek, D. M., Rostomyan, T., Schaab, D., Schmidt, Ch, Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Sowa, C., Spieker, K., Thiel, A., Thoma, U., Triffterer, T., Urban, M., van Pee, H., Walther, D., Wendel, Ch, Werthmüller, D., Wiedner, U., Witthauer, L., Wunderlich, Y., and Zaunick, H. G.
Subjects: Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract: The photoproduction of ω and η mesons off carbon and niobium nuclei has been measured as a function of the meson momentum for incident photon energies of 1.2-2.9GeV at the electron accelerator ELSA. The mesons have been identified via the ω → π0 γ → 3 γ and η → π0η → 6 γ 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 ω and η 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 ω width and η-N absorption cross sections. The energy dependence of the imaginary part of the ω- and η-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 η-nucleus potential is found to be about three times smaller than recently determined values of the real part of the η-nucleus potential, which makes the η meson a suitable candidate for the search for meson-nucleus bound states. For the ω 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 ω mesic states very difficult experimentally.
Published: 2016

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

Author: Nanova, M., Friedrich, S., Metag, V., Paryev, E. Ya, Afzal, F. N., Bayadilov, D., Beck, R., Becker, M., Böse, S., Brinkmann, K. T., Crede, V., Elsner, D., Frommberger, F., Grüner, M., Gutz, E., Hammann, Ch, Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, P., Honisch, Ch, Jude, T., Kalischewski, F., Keshelashvili, I., Klein, F., Koop, K., Krusche, B., Makonyi, K., Messi, F., Müller, J., Müllers, J., Piontek, D. M., Rostomyan, T., Schaab, D., Schmidt, C., Schmieden, H., Schmitz, R., Seifen, T., Sowa, C., Spieker, K., Thiel, A., Thoma, U., Triffterer, T., Urban, M., Van Pee, H., Walther, D., Wendel, C., Wiedner, U., Witthauer, L., and Werthmüller, Dominik
Subjects: Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract: The excitation function and momentum distribution of η′ mesons have been measured in photoproduction off Nb93 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 η′-Nb potential has been extracted from a comparison of the data with model calculations. An attractive potential of -(41±10(stat)±15(syst)) MeV depth at normal nuclear matter density is deduced within model uncertainties. This value is consistent with the potential depth of -(37±10(stat)±10(syst)) MeV obtained in an earlier measurement for a light nucleus (carbon). This relatively shallow η′-nucleus potential will make the search for η′-nucleus bound states more difficult.
Published: 2016

21. Determination of the real part of the ��'-Nb optical potential

Author: Nanova, M., Friedrich, S., Metag, V., Paryev, E. Ya., Afzal, F. N., Bayadilov, D., Beck, R., Becker, M., B��se, S., Brinkmann, K. -T., Crede, V., Elsner, D., Frommberger, F., Grtuner, M., Gutz, E., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, P., Honisch, Ch., Jude, T., Kalischewski, F., Keshelashvili, I., Klein, F., Koop, K., Krusche, B., Lang, M., Makonyi, K., Messi, F., M��ller, J., M��llers, J., Piontek, D. M., Rostomyan, T., Schaab, D., Schmidt, C., Schmieden, H., Schmitz, R., Seifen, T., Sowa, C., Spieker, K., Thiel, A., Thoma, U., Tristerer, T., Urban, M., van Pee, H., Walther, D., Wendel, C., Werthm��ller, D., Wiedner, U., Wilson, A., Witthauer, L., Wunderlich, Y., and Zaunick, H. -G.
Subjects: Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: The excitation function and momentum distribution of ��' 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 ��'-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 ��'-nucleus potential will make the search for ��'-nucleus bound states more difficult., 9 pages, 6 figures
Published: 2016
Full Text: View/download PDF

22. The Impact of New Polarization Data from Bonn, Mainz and Jefferson Laboratory on $��p \to ��N$ Multipoles

Author: Beck, A. V. Anisovich R., D��ring, M., Gottschall, M., Hartmann, J., Kashevarov, V., Klempt, E., Mei��ner, Ulf-G., Nikonov, V., Ostrick, M., R��nchen, D., Sarantsev, A., Strakovsky, I., Thiel, A., Tiator, L., Thoma, U., Workman, R., and Wunderlich, Y.
Subjects: Nuclear Theory (nucl-th), Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: New data on pion-photoproduction off the proton have been included in the partial wave analyses Bonn-Gatchina and SAID and in the dynamical coupled-channel approach J��lich-Bonn. All reproduce the recent new data well: the double polarization data for E, G, H, P and T in $��p \to ��^0 p$ from ELSA, the beam asymmetry $��$ for $��p \to ��^0 p$ and $��^+ n$ from Jefferson Laboratory, and the precise new differential cross section and beam asymmetry data $��$ for $��p \to ��^0 p$ from MAMI. The new fit results for the multipoles are compared with predictions not taking into account the new data. The mutual agreement is improved considerably but still far from being perfect.
Published: 2016
Full Text: View/download PDF

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

Author: Friedrich, S., Nanova, M., Metag, V., Afzal, F. N., Bayadilov, D., Bantes, B., Beck, R., Becker, M., B��se, S., Brinkmann, K. -T., Crede, V., Drexler, P., Eberhardt, H., Elsner, D., Frommberger, F., Funke, Ch., Gottschall, M., Gr��ner, M., Gutz, E., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kaiser, D., Kalischewski, F., Keshelashvili, I., Klein, F., Koop, K., Krusche, B., Lang, M., Makonyi, K., Messi, F., M��ller, J., M��llers, J., Piontek, D. -M., Rostomyan, T., Schaab, D., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Sowa, C., Spieker, K., Thiel, A., Thoma, U., Triffterer, T., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Werthm��ller, D., Wiedner, U., Wilson, A., Witthauer, L., Wunderlich, Y., and Zaunick, H. -G.
Subjects: High Energy Physics::Phenomenology, Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: The photoproduction of $��$ and $��^\prime$ 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 $��\rightarrow ��^0 ��\rightarrow 3 ��$ and $��^\prime\rightarrow ��^0 ��^0��\rightarrow 6 ��$ 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 $��$ and $��^\prime$ 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 $��$ width and $��^\prime$-N absorption cross sections. The energy dependence of the imaginary part of the $��$- and $��^\prime$-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 $��^\prime$ nucleus potential is found to be about three times smaller than recently determined values of the real part of the $��^\prime$-nucleus potential, which makes the $��^\prime$ meson a suitable candidate for the search for meson-nucleus bound states. For the $��$ 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 $��$ mesic states very difficult experimentally., 10 pages, 8 figures
Published: 2016
Full Text: View/download PDF

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

Author: Hartmann, J., Dutz, H., Anisovich, A.V., Bayadilov, D., Beck, R., Becker, M., Beloglazov, Y., Berlin, A., Bichow, M., Böse, S., Brinkmann, K.-Th., Crede, V., Dieterle, M., Eberhardt, H., Elsner, D., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Funke, Ch., Gottschall, M., Gridnev, A., Grüner, M., Goertz, St., Gutz, E., Hammann, Ch., Hannappel, J., Hannen, V., Herick, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jahn, O., Jude, T., Käser, A., Kaiser, D., Kalinowsky, H., Kalischewski, F., Klassen, P., Keshelashvili, I., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Makonyi, K., Messi, F., Metag, V., Meyer, W., Müller, J., Nanova, M., Nikonov, V., Novinski, D., Novotny, R., Piontek, D., Reeve, S., Rosenbaum, Ch., Roth, B., Reicherz, G., Rostomyan, T., Runkel, St., Sarantsev, A., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Thämer, Ph., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Wiedner, U., Wilson, A., Winnebeck, A., and Witthauer, L.
Subjects: Polarization observables, Baryon spectroscopy, Nuclear Theory, Nuclear Experiment, Multipoles, Meson photoproduction, lcsh:Physics, lcsh: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

25. The polarization observables T, P, and H and their impact on $\gamma p \to p\pi^0$ multipoles

Author: Hartmann, J., Dutz, H., Anisovich, A. V., Bayadilov, D., Beck, R., Becker, M., Beloglazov, Y., Berlin, A., Bichow, M., Böse, S., Brinkmann, K. -Th., Crede, V., Dieterle, M., Eberhardt, H., Elsner, D., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Funke, Ch., Gottschall, M., Gridnev, A., Grüner, M., Görtz, St., Gutz, E., Hammann, Ch., Hannappel, J., Hannen, V., Herick, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jahn, O., Jude, T., Käser, A., Kaiser, D., Kalinowsky, H., Kalischewski, F., Klassen, P., Keshelashvili, I., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Makonyi, K., Messi, F., Metag, V., Meyer, W., Müller, J., Nanova, M., Nikonov, V., Novinski, D., Novotny, R., Piontek, D., Reeve, S., Rosenbaum, Ch., Roth, B., Reicherz, G., Rostomyan, T., Runkel, St., Sarantsev, A., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Thämer, Ph., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Wiedner, U., Wilson, A., Winnebeck, A., and Witthauer, L.
Subjects: Nuclear Theory, Nuclear Experiment
Abstract: Data on the polarization observables T, P, and H for the reaction $\gamma p\to p\pi^0$ 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.
Published: 2015

26. Interference phenomena in the $J^P=1/2^-$-wave in $\eta$ photoproduction

Author: Anisovich, A. V., Klempt, E., Krusche, B., Nikonov, V. A., Sarantsev, A. V., Thoma, U., and Werthmüller, D.
Subjects: Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract: The recent precise experimental results for the photoproduction of $\eta$-mesons off the neutron measured with the Crystal Ball/TAPS calorimeter at the MAMI accelerator have been investigated in detail in the framework of the Bonn-Gatchina coupled channel model. The main result is that the narrow structure observed in the excitation function of $\gamma n \rightarrow n\eta$ can be reproduced fully with a particular interference pattern in the $J^P=1/2^-$ partial wave. Introduction of the narrow resonance $N(1685)$ with the properties reported in earlier publications deteriorates the quality of the fit., Comment: 10 pages, 13 figures, accepted for publication in EPJA
Published: 2015

27. The polarization observables T, P, and H and their impact on $��p \to p��^0$ multipoles

Author: Hartmann, J., Dutz, H., Anisovich, A. V., Bayadilov, D., Beck, R., Becker, M., Beloglazov, Y., Berlin, A., Bichow, M., B��se, S., Brinkmann, K. -Th., Crede, V., Dieterle, M., Eberhardt, H., Elsner, D., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Funke, Ch., Gottschall, M., Gridnev, A., Gr��ner, M., G��rtz, St., Gutz, E., Hammann, Ch., Hannappel, J., Hannen, V., Herick, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jahn, O., Jude, T., K��ser, A., Kaiser, D., Kalinowsky, H., Kalischewski, F., Klassen, P., Keshelashvili, I., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Makonyi, K., Messi, F., Metag, V., Meyer, W., M��ller, J., Nanova, M., Nikonov, V., Novinski, D., Novotny, R., Piontek, D., Reeve, S., Rosenbaum, Ch., Roth, B., Reicherz, G., Rostomyan, T., Runkel, St., Sarantsev, A., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Th��mer, Ph., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Wiedner, U., Wilson, A., Winnebeck, A., and Witthauer, L.
Subjects: Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: Data on the polarization observables T, P, and H for the reaction $��p\to p��^0$ 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.
Published: 2015
Full Text: View/download PDF

28. Comment on 'Narrow Structure in the Excitation Function of $\eta$\ Photoproduction off the Neutron'

Author: Anisovich, A. V., Klempt, E., Nikonov, V. A., Sarantsev, A. V., and Thoma, U.
Subjects: Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract: It is shown that the narrow structure observed in the excitation function of $\eta$ photoproduction off the Neutron originates from the interference of the two $S_{11}$ resonances., Comment: 1 page, 2 figures
Published: 2014

29. Experimental constraints on the $��$-nucleus real potential

Author: Friedrich, S., Makonyi, K., Metag, V., Bayadilov, D., Bantes, B., Beck, R., Beloglazov, Y. A., B��se, S., Brinkmann, K. -T., Challand, Th., Crede, V., Dahlke, T., Dietz, F., Drexler, P., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Frommberger, F., Funke, Ch., Gottschall, M., Gridnev, A., Gr��ner, M., Gutz, E., Hammann, Ch., Hammann, D., Hannappel, J., Hartmann, J., Hillert, W., Hirenzaki, S., Hoffmeister, P., Honisch, Ch., Jaegle, I., Kaiser, D., Kalinowsky, H., Kammer, S., Keshelashvili, I., Kleber, V., Klein, F., Krusche, B., Lang, M., Lopatin, I. V., Maghrbi, Y., Nanova, M., Nagahiro, H., M��ller, J., Odenthal, T., Piontek, D., Rostomyan, T., Schaepe, S., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Thiel, A., Thoma, U., van Pee, H., Walther, D., Weil, J., Wendel, Ch., Wiedner, U., Wilson, A., Winnebeck, A., and Zenke, F.
Subjects: Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: In a search for $��$ mesic states, the production of $��$-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 $��^0 ��$ pairs from decays of bound or quasi-free $��$-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 $��^0 ��$ pairs, which would indicate the population and decay of bound $��~^{11}$B states, are not observed. The $��^0 ��$ 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 $��$-meson. A comparison of the measured total energy distribution with calculations suggests the real part $V_0$ of the $��~^{11}$B potential to be small and only weakly attractive with $V_0(��=��_0) = -15\pm$ 35(stat) $\pm$20(syst) MeV in contrast to some theoretical predictions of attractive potentials with a depth of 100 - 150 MeV., 13 pages, 8 figures
Published: 2014
Full Text: View/download PDF

30. First measurement of the helicity asymmetry for $\gamma p\rightarrow p\pi^0$ in the resonance region

Author: Gottschall, M., Anisovich, A. V., Bantes, B., Bayadilov, D., Beck, R., Bichow, M., Böse, S., Brinkmann, K. -Th., Challand, Th., Crede, V., Dietz, F., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Funke, Ch., Gridnev, A., Grüner, M., Gutz, E., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jaegle, I., Kaiser, D., Kalinowsky, H., Kammer, S., Keshelashvili, I., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Maghrbi, Y., Makonyi, K., Metag, V., Meyer, W., Müller, J., Nanova, M., Nikonov, V., Novotny, R., Piontek, D., Reicherz, G., Rostomyan, T., Sarantsev, A., Schaepe, St., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Wiedner, U., Wilson, A., and Winnebeck, A.
Subjects: Nuclear Theory, Nuclear Experiment
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

31. Determination of the ��'-nucleus optical potential

Author: Nanova, M., Metag, V., Paryev, E. Ya., Bayadilov, D., Bantes, B., Beck, R., Beloglazov, Y. A., B��se, S., Brinkmann, K. -T., Challand, Th., Crede, V., Dahlke, T., Dietz, F., Drexler, P., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, S., Frommberger, F., Funke, Ch., Gottschall, M., Gridnev, A., Gr��ner, M., Gutz, E., Hammann, Ch., Hammann, D., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, P., Honisch, Ch., Jaegle, I., Kaiser, D., Kalinowsky, H., Kammer, S., Keshelashvili, I., Kleber, V., Klein, F., Klempt, E., Krusche, B., Lang, M., Lopatin, I. V., Maghrbi, Y., Makonyi, K., M��ller, J., Odenthal, T., Piontek, D., Schaepe, S., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Thiel, A., Thoma, U., van Pee, H., Walther, D., Wendel, Ch., Wiedner, U., Wilson, A., Winnebeck, A., and Zenke, F.
Subjects: Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: The excitation function and momentum distribution of $��^\prime$ 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 $��^\prime$-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 $��^\prime$-nucleus potential of -($10\pm2.5$) MeV, determined by transparency ratio measurements, a search for resolved $��^\prime$-bound states appears promising., 13 pages, 6 figures
Published: 2013
Full Text: View/download PDF

32. First measurement of the helicity asymmetry for $��p\rightarrow p��^0$ in the resonance region

Author: Gottschall, M., Anisovich, A. V., Bantes, B., Bayadilov, D., Beck, R., Bichow, M., B��se, S., Brinkmann, K. -Th., Challand, Th., Crede, V., Dietz, F., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Funke, Ch., Gridnev, A., Gr��ner, M., Gutz, E., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jaegle, I., Kaiser, D., Kalinowsky, H., Kammer, S., Keshelashvili, I., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Maghrbi, Y., Makonyi, K., Metag, V., Meyer, W., M��ller, J., Nanova, M., Nikonov, V., Novotny, R., Piontek, D., Reicherz, G., Rostomyan, T., Sarantsev, A., Schaepe, St., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Wiedner, U., Wilson, A., and Winnebeck, A.
Subjects: Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
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
Full Text: View/download PDF

33. Transparency ratio in \gamma A -> \eta' A' and the in-medium \eta' width

Author: Nanova, M., Metag, V., Ramos, A., Oset, E., Jaegle, I., Makonyi, K., Brinkmann, K., Bartholomy, O., Bayadilov, D., Beloglazov, Y. A., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fuchs, M., Funke, Ch., Gregor, R., Gridnev, A. B., Gutz, E., Höffgen, S., Hoffmeister, P., Horn, I., Junkersfeld, J., Kalinowsky, H., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kopf, B., Krusche, B., Langheinrich, J., Löhner, H., Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Mertens, T., Messchendorp, J. G., Morales, C., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Roy, A., Radkov, A., Schadmand, S., Schmidt, Ch., Schmieden, H., Schoch, B., Süle, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., and Wendel, Ch.
Subjects: Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract: The photoproduction of \eta'-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 \eta'-mesons in nuclei. The comparison indicates a width of the \eta' -meson of the order of \Gamma= 15-25 MeV at \rho =\rho_0 for an average momentum p_{\eta'} = 1050 MeV/c, at which the \eta'-meson is produced in the nuclear rest frame. The inelastic \eta' N cross section is estimated to be 3 - 10 mb. Parameterizing the photoproduction cross section of \eta'-mesons by \sigma(A) = \sigma_0 A^{\alpha}, a value of \alpha = 0.84\pm0.03 has been deduced., Comment: 14 pages, 6 figures
Published: 2012

34. Pion- and photo-induced transition amplitudes to $��K$, $��K$, and $N��$

Author: Anisovich, A. V., Beck, R., Klempt, E., Nikonov, V. A., Sarantsev, A. V., and Thoma, U.
Subjects: Nuclear Theory (nucl-th), Nuclear Theory, FOS: Physical sciences, Nuclear Experiment
Abstract: Pion and photo-induced inelastic reactions off protons are studied in a multichannel partial-wave analysis. Properties of nucleon and $��$ resonances are derived and compared to previous analyses. Amplitudes are shown for transitions to $N��$, $��K$, and $��K$ final states., 9 pages, 6 figures
Published: 2012
Full Text: View/download PDF

35. Photoproduction of eta'-mesons off the deuteron

Author: Jaegle, I., Mertens, T., Fix, A., Huang, F., Nakayama, K., Tiator, L., Anisovich, A. V., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D. E., Beck, R., Beloglazov, Y. A., Castelijns, R., Crede, V., Dutz, H., Elsner, D., Ewald, R., Frommberger, F., Funke, C., Gregor, R., Gridnev, A. B., Gutz, E., Hillert, W., Hoeffgen, S., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Kotulla, M., Krusche, B., Lang, M., Loehner, H., Lopatin, I. V., Lugert, S., Menze, D., Messchendorp, J. G., Metag, V., Nikonov, V. A., Nanova, M., Novinski, D. V., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Roy, A., Sarantsev, A. V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S. V., Sokhoyan, V., Suele, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Wendel, C., and Publica
Subjects: Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract: Quasi-free photoproduction of $\eta '$ 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 2.5 GeV. The $\eta '$-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 $\gamma n \rightarrow n\eta '$ reaction. In addition, also first estimates for coherent $\eta '$-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., Comment: Accepted for publication in Eur. Phys. J. A
Published: 2011

36. Photoproduction of omega mesons on nuclei near the production threshold

Author: Nanova, M., Weil, J., Friedrich, S., Metag, V., Mosel, U., Thiel, M., Anton, G., Bacelar, J.C.S., Bartholomy, O., Bayadilov, D., Beloglazov, Y.A., Bogendörfer, R., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fuchs, M., Funke, C., Gothe, R., Gregor, R., Gridnevm, A.B., Gutz, E., Höffgen, Stefan Klaus, Hoffmeister, P., Horn, I., Hössl, J., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Klein, F., Klempt, E., Konrad, M., Kopf, B., Kotulla, M., Krusche, B., Langheinrich, J., Löhner, H., Lopatin, I.V., Lotz, J., Lugert, S., Menze, M., Mertens, T., Messchendorp, J.G., Morales, C., Novotny, R., Ostrick, M., Pant, L.M., Pee, H. van, Pfeiffer, M., Roy, A., Radkov, A., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Suft, G., Süle, A., Sumachev, V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Weinheimer, C., Wendel, C., Publica, KVI - Center for Advanced Radiation Technology, and Research unit Nuclear & Hadron Physics
Subjects: Physics, Nuclear and High Energy Physics, Photon, Meson, ENERGIES, Significant difference, Nuclear Theory, Omega, Nuclear physics, Production (computer science), Sensitivity (control systems), Nucleon, Nuclear Experiment, Line (formation)
Abstract: The photoproduction of $\omega$ mesons on LH_2, C and Nb has been studied for incident photon energies from 900 to 1300 MeV using the CB/TAPS detector at ELSA. The $\omega$ line shape does not show any significant difference between the LH_2 and the Nb targets. The data are compared with results of transport calculations that predict a sensitivity of the $\omega$ line shape to in-medium modifications near the production threshold on a free nucleon of $E_{\gamma}^{lab}$ = 1109 MeV.}, Comment: 5 pages, 3 figures
Published: 2011

37. Evidence for a backward peak in the gamma d -> pi(0)d cross section near the eta threshold

Author: Ilieva, Y., Berman, B. L., Kudryavtsev, A. E., Strakovsky, I. I., Tarasov, V. E., Amarian, M., Ambrozewicz, P., Anghinolfi, M., Asryan, G., Avakian, H., Bagdasaryan, H., Baillie, N., Ball, J. P., Baltzell, N. A., Batourine, V., Battaglieri, M., Bedlinskiy, I., Bellis, M., Benmouna, N., Biselli, A. S., Bouchigny, S., Boiarinov, S., Bradford, R., Branford, D., Briscoe, W. J., Brooks, W. K., Bültmann, S., Burkert, V. D., Butuceanu, C., Calarco, J. R., Careccia, S. L., Carman, D. S., Chen, S., Cole, P. L., Collins, P., Coltharp, P., Crabb, D., Crede, V., De Masi, R., De Sanctis, E., De Vita, R., Degtyarenko, P. V., Deur, A., Dickson, R., Djalali, C., Dodge, G. E., Donnelly, J., Doughty, D., Dugger, M., Dzyubak, O. P., Egiyan, H., Egiyan, K. S., Elouadrhiri, L., Eugenio, P., Fedotov, G., Feldman, G., Funsten, H., Garçon, M., Gavalian, G., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Goetz, J. T., Gonenc, A., Gothe, R. W., Griffioen, K. A., Guidal, M., Guler, N., Guo, L., Gyurjyan, V., Hafidi, K., Hakobyan, R. S., Hersman, F. W., Hicks, K., Hleiqawi, I., Holtrop, M., Hyde Wright, C. E., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Ito, M. M., Jenkins, D., H. S., Jo, Joo, K., Juengst, H. G., Kalantarians, N., Kellie, J. D., Khandaker, M., Kim, W., Klein, A., Klein, F. J., Kossov, M., Krahn, Z., Kramer, L. H., Kubarovsky, V., Kuhn, J., Kuhn, S. E., Kuleshov, S. V., Lachniet, J., Laget, J. M., Langheinrich, J., Lawrence, D., Livingston, K., Lu, H., Maccormick, M., Markov, N., Mckinnon, B., Mecking, B. A., Mestayer, M. D., Meyer, C. A., Mibe, T., Mikhailov, K., Mirazita, M., Miskimen, R., Mokeev, V., Moriya, K., Morrow, S. A., Moteabbed, M., Munevar, E., Mutchler, G. S., Nadel Turonski, P., Nasseripour, R., Niccolai, S., Niculescu, G., Niculescu, I., Niczyporuk, B. B., Niroula, M. R., Niyazov, R. A., Nozar, M., Osipenko, M., Ostrovidov, A. I., Park, K., Pasyuk, E., Paterson, C., Pierce, J., Pivnyuk, N., Pogorelko, O., Pozdniakov, S., Price, J. W., Prok, Y., Protopopescu, D., Raue, B. A., Ricco, Giovanni, Ripani, M., Ritchie, B. G., Ronchetti, F., Rosner, G., Rossi, P., Sabatié, F., Salgado, C., Santoro, J. P., Sapunenko, V., Schumacher, R. A., Serov, V. S., Sharabian, Y. G., Shvedunov, N. V., Smith, E. S., Smith, L. C., Sober, D. I., Stavinsky, A., Stepanyan, S. S., Stepanyan, S., Stokes, B. E., Stoler, P., Strauch, S., Taiuti, MAURO GINO, Tedeschi, D. J., Thoma, U., Tkabladze, A., Tkachenko, S., Tur, C., Ungaro, M., Vineyard, M. F., Vlassov, A. V., Watts, D. P., Weinstein, L. B., Weygand, D. P., Williams, M., Wolin, E., Wood, M. H., Yegneswaran, A., Zana, L., Zhang, J., Zhao, B., and Zhao, Z.
Subjects: Nuclear and High Energy Physics, D ELASTIC-SCATTERING, COHERENT PION-PHOTOPRODUCTION, D ELASTIC-SCATTERING, DIBARYON RESONANCES, NEAR-THRESHOLD, MESIC NUCLEUS, BOUND-STATES, DEUTERON, MESON, SIGNATURE, REGION, DIBARYON RESONANCES, Nuclear Theory, MESIC NUCLEUS, COHERENT PION-PHOTOPRODUCTION, Resonance (particle physics), BOUND-STATES, REGION, Nuclear physics, Pion, Intermediate state, NEAR-THRESHOLD, Nuclear Experiment, Physics, Range (particle radiation), Eta meson, SIGNATURE, DEUTERON, Amplitude, High Energy Physics::Experiment, MESON, Nucleon, Excitation
Abstract: High-quality cross sections for the reaction gamma+d->pi^0+d have been measured using the CLAS at Jefferson Lab over a wide energy range near and above the eta-meson photoproduction threshold. At backward c.m. angles for the outgoing pions, we observe a resonance-like structure near E_gamma=700 MeV. Our model analysis shows that it can be explained by eta excitation in the intermediate state. The effect is the result of the contribution of the N(1535)S_11 resonance to the amplitudes of the subprocesses occurring between the two nucleons and of a two-step process in which the excitation of an intermediate eta meson dominates., Comment: slightly modified title, additional paragraph and a table (Table 2) added on p. 5; to be submitted to EPJA, 6 pages, 3 figures
Published: 2010

38. Photoproduction of $��$ mesons on nuclei near the production threshold

Author: Nanova, M., Weil, J., Friedrich, S., Metag, V., Mosel, U., Anton, G., Bacelar, J. C. S., Bartholomy, O., Bayadilov, D., Beloglazov, Y. A., Bogend��rfer, R., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fuchs, M., Funke, Ch., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., H��ffgen, S., Hoffmeister, P., Horn, I., H��ssl, J., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kopf, B., Kotulla, M., Krusche, B., Langheinrich, J., L��hner, H., Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Mertens, T., Messchendorp, J. G., Morales, C., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Roy, A., Radkov, A., Schadmand, S., Schmidt, Ch., Schmieden, H., Schoch, B., Shende, S., Suft, G., S��le, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Weinheimer, Ch., and Wendel, Ch.
Subjects: Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: The photoproduction of $��$ mesons on LH_2, C and Nb has been studied for incident photon energies from 900 to 1300 MeV using the CB/TAPS detector at ELSA. The $��$ line shape does not show any significant difference between the LH_2 and the Nb targets. The data are compared with results of transport calculations that predict a sensitivity of the $��$ line shape to in-medium modifications near the production threshold on a free nucleon of $E_��^{lab}$ = 1109 MeV.}, 5 pages, 3 figures
Published: 2010
Full Text: View/download PDF

39. Photoproduction of $��'$-mesons off the deuteron

Author: Jaegle, I., Mertens, T., Fix, A., Huang, F., Nakayama, K., Tiator, L., Anisovich, A. V., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D. E., Beck, R., Beloglazov, Y. A., Castelijns, R., Crede, V., Dutz, H., Elsner, D., Ewald, R., Frommberger, F., Funke, C., Gregor, R., Gridnev, A. B., Gutz, E., Hillert, W., Hoeffgen, S., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Kotulla, M., Krusche, B., Lang, M., Loehner, H., Lopatin, I. V., Lugert, S., Menze, D., Messchendorp, J. G., Metag, V., Nikonov, V. A., Nanova, M., Novinski, D. V., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Roy, A., Sarantsev, A. V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S. V., Sokhoyan, V., Suele, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., and Wendel, C.
Subjects: Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: Quasi-free photoproduction of $��'$ 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 2.5 GeV. The $��'$-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 $��n \rightarrow n��'$ reaction. In addition, also first estimates for coherent $��'$-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., Accepted for publication in Eur. Phys. J. A
Published: 2010
Full Text: View/download PDF

40. Photoproduction of $\eta$ and $\eta\prime$ Mesons off Protons

Author: CBELSA, The, Collaboration, TAPS, Crede, Volker, McVeigh, A., Anisovich, A., Bacelar, J., Bantes, R., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y., Castelijns, R., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fuchs, M., Funke, C., Gothe, R., Gregor, R., Gridnev, A., Gutz, E., Hoeffgen, S., Hoffmeister, P., Horn, I., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kotulla, M., Krusche, B., Langheinrich, J., Loehner, H., Lopatin, I., Lotz, J., Lugert, S., Menze, D., Mertens, T., Messchendorp, J., Metag, V., Nanova, M., Nikonov, V., Novinski, D., Novotny, R., Ostrick, M., Pant, L., van Pee, H., Pfeiffer, M., Roy, A., Sarantsev, A., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Sparks, N., Suele, A., Sumachev, V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Weinheimer, C., Wendel, C., and Wilson, A.
Subjects: Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract: Total and differential cross sections for $\eta$ and $\eta ^\prime$ 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, $\eta\to\gamma\gamma$ and $\eta\to 3\pi^0\to 6\gamma$, and for the first time, cover the full angular range in $\rm cos \theta_{cm}$ of the $\eta$ meson. These new $\eta$ photoproduction data are consistent with the earlier CB-ELSA results. The $\eta ^\prime$ mesons are observed in their neutral decay to $\pi^0\pi^0\eta\to 6\gamma$ and also extend the coverage in angular range., Comment: 13 pages, 21 figures, updated author list, submitted to PRC
Published: 2009

41. Photoproduction of eta-mesons off nuclei for E(gamma)

Author: Mertens, T., Jaegle, I., Muehlich, P., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D. E., Beck, R., Beloglazov, Y. A., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fornet-Ponse, K., Fuchs, M., Funke, C., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Hoeffgen, S., Hoffmeister, P., Horn, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kotulla, M., Krusche, B., Lang, M., Langheinrich, J., Loehner, H., Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Messchendorp, J. G., Metag, V., Morales, C., Mosel, U., Nanova, M., Novinski, D. V., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Radkov, A. K., Roy, A., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S. V., Sokhoyan, V., Suele, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Weinheimer, C., Wendel, C., and KVI - Center for Advanced Radiation Technology
Subjects: IN-MEDIUM PROPERTIES, BARYON RESONANCES, Nuclear Theory, NEAR-THRESHOLD PHOTOPRODUCTION, BEAM ASYMMETRY, High Energy Physics::Experiment, EXCLUSIVE MEASUREMENT, PHOTOABSORPTION, Nuclear Experiment, PROTON, CROSS-SECTION, DEUTERON, REGION
Abstract: The 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 modi. cations of the S(11)(1535).
Published: 2008

42. Photoproduction of $��$ mesons off neutrons from a deuteron target

Author: Anisovich, A. V., Jaegle, I., Klempt, E., Krusche, B., Nikonov, V. A., Sarantsev, A. V., and Thoma, U.
Subjects: High Energy Physics - Phenomenology (hep-ph), Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment
Abstract: A formalism is developed for the partial wave analysis of data on meson photoproduction off deuterons and applied to photoproduction of $��$ and $��^0$ mesons. Different interpretations of a dip-bump structure of the $��$ photoproduction cross section in the 1670 MeV region are presented and discussed. Helicity amplitudes for two low-mass $S_{11}$ states are determined., 11 pages, 13 figures
Published: 2008
Full Text: View/download PDF

43. Quasi-free photoproduction of eta-mesons of the neutron

Author: Jaegle, I., Mertens, T., Anisovich, A. V., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y. A., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fuchs, M., Funke, C., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Hoeffgen, S., Hoffmeister, P., Horn, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kotulla, M., Krusche, B., Lang, M., Langheinrich, J., Loehner, H., Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Messchendorp, J. G., Metag, V., Morales, C., Nanova, M., Nikonov, V. A., Novinski, D. V., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Radkov, A. K., Roy, A., Sarantsev, A. V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Sokhoyan, V., Suele, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Weinheimer, C., and Wendel, C.
Subjects: Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: Quasi-free photoproduction of eta-mesons off nucleons bound in the deuteron has been measured with the CBELSA/TAPS detector for incident photon energies up to 2.5 GeV at the Bonn ELSA accelerator. The eta-mesons have been detected in coincidence with recoil protons and recoil neutrons, which allows a detailed comparison of the quasi-free n(gamma,eta)n and p(gamma,eta)p reactions. The excitation function for eta-production off the neutron shows a pronounced bump-like structure at W=1.68 GeV (E_g ~ 1 GeV), which is absent for the proton., Comment: accepted for publication in Phys. Rev. Lett
Published: 2008
Full Text: View/download PDF

44. Photoproduction of eta-mesons off nuclei for Eg < 2.2 GeV

Author: Mertens, T., Jaegle, I., Muehlich, P., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D. E., Beck, R., Beloglazov, Y. A., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fornet-Ponse, K., Fuchs, M., Funke, C., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Hoeffgen, S., Hoffmeister, P., Horn, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kotulla, M., Krusche, B., Lang, M., Langheinrich, J., Loehner, H., Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Messchendorp, J. G., Metag, V., Morales, C., Mosel, U., Nanova, M., Novinski, D. V., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Radkov, A. K., Roy, A., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Sokhoyan, V., Suele, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Weinheimer, C., and Wendel, C.
Subjects: Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: Photoproduction of $��$ 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 $��$ mesons. Careful consideration was given to contributions from $��$ final states and secondary production mechanisms of $��$-mesons e.g. from inelastic $��N$ reactions of intermediate pions. The analysis of the mass number scaling shows that the nuclear absorption cross section $��_{N��}$ for $��$ mesons is constant over a wide range of the $��$ 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)., Accepted for publication in Eur. Phys. J. A
Published: 2008
Full Text: View/download PDF

45. Photoproduction of π 0 ω off protons for E γ ≤3 GeV

Author: Junkersfeld, J., Anisovich, A. V., Anton, G., Bantes, R., Bartholomy, O., Beck, R., Beloglazov, Yu, Bogendoerfer, R., Castelijns, R., Crede, V., Ehmanns, A., Ernst, J., Fabry, I., Flemming, H., Foesel, A., Fuchs, M., Funke, Ch, Gothe, R., Gridnev, A., Gutz, E., Hoeffgen, St, Horn, I., Hossl, J., Kalinowsky, H., Klein, F., Klempt, E., Koch, H., Konrad, M., Kopf, B., Krusche, B., Langheinrich, J., Löhner, H., Lopatin, I., Lotz, J., Mattaey, H., Menze, D., Messchendorp, J., Nikonov, V. A., Novinski, D., Ostrick, M., van Pee, H., Radkov, A., Sarantsev, A. V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Suft, G., Sumachev, V., Szczepanek, T., Thoma, U., Walther, D., Weinheimer, Ch, and KVI - Center for Advanced Radiation Technology
Subjects: Physics, Nuclear and High Energy Physics, Range (particle radiation), Proton, Nuclear Theory, Particle accelerator, Photon energy, Omega, ETA, MESONS, DECAYS, law.invention, LAMBDA, Nuclear physics, RELATIVISTIC QUARK-MODEL, law, PHOTON ENERGIES, STRANGE-BARYON SPECTRUM, Physics::Accelerator Physics, High Energy Physics::Experiment, SIGMA(0), FORCES, Nuclear Experiment, RESONANCES
Abstract: Differential and total cross-sections for photoproduction of gamma proton to proton pi0 omega and gamma proton to Delta+ omega were determined from measurements of the CB-ELSA experiment, performed at the electron accelerator ELSA in Bonn. The measurements covered the photon energy range from the production threshold up to 3GeV.
Published: 2007

46. Experimental study of exclusive $^2$H$(e,e^\prime p)n$ reaction mechanisms at high $Q^2$

Author: Egiyan, K.S., Asryan, G., Gevorgyan, N., Griffioen, K.A., Laget, J.M., Kuhn, S.E., Adams, G., Amaryan, M.J., Ambrozewicz, P., Anghinolfi, M., Audit, G., Avakian, H., Bagdasaryan, H., Baillie, N., Ball, J.P., Baltzell, N.A., Barrow, S., Batourine, V., Battaglieri, M., Bedlinskiy, I., Bektasoglu, M., Bellis, M., Benmouna, N., Berman, B.L., Biselli, A.S., Blaszczyk, L., Bouchigny, S., Boiarinov, S., Bradford, R., Branford, D., Briscoe, W.J., Brooks, W.K., Bültmann, S., Burkert, V.D., Butuceanu, C., Calarco, J.R., Careccia, S.L., Carman, D.S., Cazes, A., Chen, Si, Cole, P.L., Collins, P., Coltharp, P., Cords, D., Corvisiero, P., Crabb, D., Crede, V., Cummings, J.P., Dashyan, N., De Masi, R., De Vita, R., De Sanctis, E., Degtyarenko, P.V., Denizli, H., Dennis, L., Deur, A., Dharmawardane, K.V., Dickson, R., Djalali, C., Dodge, G.E., Donnelly, J., Doughty, D., Dugger, M., Dytman, S., Dzyubak, O.P., Egiyan, H., El Fassi, L., Elouadrhiri, L., Eugenio, P., Fatemi, R., Fedotov, G., Feldman, G., Feuerbach, R.J., Fersch, R., Garçon, M., Gavalian, G., Gilfoyle, G.P., Giovanetti, K.L., Girod, F.X., Goetz, J.T., Gonenc, A., Gordon, C.I.O., Gothe, R.W., Guidal, M., Guillo, M., Guler, N., Guo, L., Gyurjyan, V., Hadjidakis, C., Hafidi, K., Hakobyan, H., Hakobyan, R.S., Hanretty, C., Hardie, J., Hersman, F.W., Hicks, K., Hleiqawi, I., Holtrop, M., Hyde-Wright, C.E., Ilieva, Y., Ireland, D.G., Ishkhanov, B.S., Isupov, E.L., Ito, M.M., Jenkins, D., Jo, H.S., Joo, K., Juengst, H.G., Kalantarians, N., Kellie, J.D., Khandaker, M., Kim, W., Klein, A., Klein, F.J., Klimenko, A.V., Kossov, M., Krahn, Z., Kramer, L.H., Kubarovsky, V., Kuhn, J., Kuleshov, S.V., Lachniet, J., Langheinrich, J., Lawrence, D., Li, Ji, Livingston, K., Lu, H.Y., MacCormick, M., Marchand, C., Markov, N., Mattione, P., McAleer, S., Mckinnon, B., McNabb, J.W.C., Mecking, B.A., Mehrabyan, S., Melone, J.J., Mestayer, M.D., Meyer, C.A., Mibe, T., Mikhailov, K., Minehart, R., Mirazita, M., Miskimen, R., Mokeev, V., Moriya, K., Morrow, S.A., Moteabbed, M., Mueller, J., Munevar, E., Mutchler, G.S., Nadel-Turonski, P., Nasseripour, R., Niccolai, S., Niculescu, G., Niculescu, I., Niczyporuk, B.B., Niroula, M.R., Niyazov, R.A., Nozar, M., O'Rielly, G.V., Osipenko, M., Ostrovidov, A.I., Park, K., Pasyuk, E., Paterson, C., Anefalos Pereira, S., Pierce, J., Pivnyuk, N., Pocanic, D., Pogorelko, O., Pozdniakov, S., Preedom, B.M., Price, J.W., Prok, Y., Protopopescu, D., Raue, B.A., Riccardi, G., Ricco, G., Ripani, M., Ritchie, B.G., Ronchetti, F., Rosner, G., Rossi, P., Sabatié, F., Salamanca, J., Salgado, C., Santoro, J.P., Sapunenko, V., Schumacher, R.A., Serov, V.S., Sharabian, Y.G., Shvedunov, N.V., Skabelin, A.V., Smith, E.S., Smith, L.C., Sober, D.I., Sokhan, D., Stavinsky, A., Stepanyan, S.S., Stepanyan, S., Stokes, B.E., Stoler, P., Strauch, S., Taiuti, M., Tedeschi, D.J., Thoma, U., Tkabladze, A., Tkachenko, S., Todor, L., Tur, C., Ungaro, M., Vineyard, M.F., Vlassov, A.V., Watts, D.P., Weinstein, L.B., Weygand, D.P., Williams, M., Wolin, E., Wood, M.H., Yegneswaran, A., Zana, L., Zhang, J., Zhao, B., Zhao, Z.W., Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), CLAS, and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 25.10.+s, 25.30.Fj, Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract: The reaction $^2$H$(e,e^\prime p)n$ has been studied with full kinematic coverage for photon virtuality $1.75, Comment: 6 pages, 4 figures
Published: 2007

47. Decays of Baryon Resonances into K Lambda, K^+ Sigma^0 and K^0 Sigma^+

Author: Sarantsev, A. V., Nikonov, V. A., Anisovich, A. V., Klempt, E., and Thoma, U.
Subjects: High Energy Physics - Experiment (hep-ex), Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment, High Energy Physics - Experiment
Abstract: Cross sections, beam asymmetries, and recoil polarisations for the reactions gamma p to K^+ Lambda ; gamma to K^+ Sigma^0, and gamma p to K^0 Sigma^+ have been measured by the SAPHIR, CLAS, and LEPS collaborations with high statistics and good angular coverage for centre-of-mass energies between 1.6 and 2.3 GeV. The combined analysis of these data with data from pi and eta photoproduction reveals evidence for new baryon resonances in this energy region. A new P_{11} state with mass 1840 MeV and width 140 MeV was observed contributing to most of the fitted reactions. The data demand the presence of two D_{13} states at 1870 and 2170 MeV., 12 pages, 16 figures
Published: 2005

48. Measurement of the Deuteron Structure Function F2 in the Resonance Region and Evaluation of Its Moments

Author: Adams, G., Ambrozewicz, P., Anghinolfi, M., Asavapibhop, B., Asryan, G., Audit, G., Avakian, H., Bagdasaryan, H., Baillie, N., Ball, J.P., Baltzell, N.A., Barrow, S., Batourine, V., Battaglieri, M., Beard, K., Bedlinskiy, I., Bektasoglu, M., Bellis, M., Benmouna, N., Bennhold, C., Biselli, A.S., Boiarinov, S., Bouchigny, S., Bradford, R., Branford, D., Briscoe, W.J., Brooks, W.K., Bültmann, S., Burkert, V.D., Butuceanu, C., Calarco, J.R., Careccia, S.L., Carman, D.S., Carnahan, B., Chen, Si, Cole, P.L., Coleman, A., Coltharp, P., Cords, D., Corvisiero, P., Crabb, D., Crannell, H., Cummings, J.P., Degtyarenko, P.V., Denizli, H., Dennis, L., De Sanctis, E., Deur, A., Devita, R., Dharmawardane, K.V., Dhuga, K.S., Djalali, C., Dodge, G.E., Donnelly, J., Doughty, D., Dragovitsch, P., Dugger, M., Dytman, S., Dzyubak, O.P., Egiyan, H., Egiyan, K.S., Elouadrhiri, L., Empl, A., Eugenio, P., Fatemi, R., Fedotov, G., Feldman, G., Feuerbach, R.J., Fix, A., Forest, T.A., Funsten, H., Gavalian, G., Gilfoyle, G.P., Giovanetti, K.L., Girod, F.X., Goetz, J.T., Gothe, R.W., Griffioen, K.A., Guidal, M., Guler, N., Guo, L., Gyurjyan, V., Hadjidakis, C., Hakobyan, R.S., Hardie, J., Heddle, D., Hersman, F.W., Hicks, K., Hleiqawi, I., Holtrop, M., Hu, J., Huertas, M., Hyde-Wright, C.E., Ilieva, Y., Ireland, D.G., Ishkhanov, B.S., Ito, M.M., Jenkins, D., Jo, H.S., Joo, K., Juengst, H.G., Kellie, J.D., Khandaker, M., Kim, K.Y., Kim, K., Kim, W., Klein, A., Klein, F.J., Klimenko, A.V., Klusman, M., Kossov, M., Kramer, L.H., Kubarovsky, V., Kuhn, J., Kuhn, S.E., Lachniet, J., Laget, J.M., Langheinrich, J., Lawrence, D., Lee, T., Lima, A.C.S., Livingston, K., Lukashin, K., Manak, J.J., Marchand, C., McAleer, S., Mckinnon, B., McNabb, J.W.C., Mecking, B.A., Mestayer, M.D., Meyer, C.A., Mibe, T., Mikhailov, K., Minehart, R., Mirazita, M., Miskimen, R., Mokeev, V., Morrow, S.A., Muccifora, V., Mueller, J., Mutchler, G.S., Nadel-Turonski, P., Napolitano, J., Nasseripour, R., Niccolai, S., Niculescu, G., Niculescu, I., Niczyporuk, B.B., Niyazov, R.A., Nozar, M., O'Rielly, G.V., Osipenko, M., Ostrovidov, A.I., Park, K., Pasyuk, E., Paterson, C., Philips, S.A., Pierce, J., Pivnyuk, N., Pocanic, D., Pogorelko, O., Polli, E., Pozdniakov, S., Preedom, B.M., Price, J.W., Prok, Y., Protopopescu, D., Qin, L.M., Raue, B.A., Riccardi, G., Ricco, G., Ripani, M., Ritchie, B.G., Roberts, W., Ronchetti, F., Rosner, G., Rossi, P., Rowntree, D., Rubin, P.D., Sabatié, F., Salgado, C., Santoro, J.P., Sapunenko, V., Schumacher, R.A., Serov, V.S., Shafi, A., Sharabian, Y.G., Shaw, J., Skabelin, A.V., Smith, E.S., Smith, L.C., Sober, D.I., Stavinsky, A., Stepanyan, S.S., Stepanyan, S., Stokes, B.E., Stoler, P., Strakovsky, I.I., Suleiman, R., Taiuti, M., Taylor, S., Tedeschi, D.J., Thoma, U., Thompson, R., Tkabladze, A., Tkachenko, S., Todor, L., Tur, C., Ungaro, M., Vineyard, M.F., Wang, K., Weinstein, L.B., Weygand, D.P., Williams, M., Wolin, E., Wood, M.H., Yegneswaran, A., Yun, J., Zana, L., Zhang, J., Strauch, S., Berman, B. L., Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and CLAS
Subjects: Nuclear Theory, MUON SCATTERING, FOS: Physical sciences, ELECTROMAGNETIC STRUCTURE, MAGNETIC FORM-FACTORS, PROTON SCATTERING, High Energy Physics - Experiment, 12.38.Cy, 12.38.Lg, 12.38.Qk, 13.60.Hb, High Energy Physics - Experiment (hep-ex), STRUCTURE-FUNCTION A(Q(2)), INELASTIC ELECTRON-SCATTERING, QUARK-HADRON DUALITY, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], RADIATIVE-CORRECTIONS, LONGITUDINAL RESPONSE FUNCTIONS, Nuclear Experiment, CROSS-SECTION, INELASTIC ELECTRON-SCATTERING, LONGITUDINAL RESPONSE FUNCTIONS, STRUCTURE-FUNCTION A(Q(2)), MAGNETIC FORM-FACTORS, QUARK-HADRON DUALITY, MUON SCATTERING, ELECTROMAGNETIC STRUCTURE, RADIATIVE-CORRECTIONS, PROTON SCATTERING, CROSS-SECTION
Abstract: PHASE; Inclusive electron scattering off the deuteron has been measured to extract the deuteron structure function F2 with the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. The measurement covers the entire resonance region from the quasielastic peak up to the invariant mass of the final-state hadronic system W~=2.7 GeV with four-momentum transfers Q2 from 0.4 to 6 (GeV/c)2. These data are complementary to previous measurements of the proton structure function F2 and cover a similar two-dimensional region of Q2 and Bjorken variable x. Determination of the deuteron F2 over a large x interval including the quasielastic peak as a function of Q2, together with the other world data, permit a direct evaluation of the structure function moments for the first time. By fitting the Q2 evolution of these moments with an OPE-based twist expansion we have obtained a separation of the leading twist and higher twist terms. The observed Q2 behavior of the higher twist contribution suggests a partial cancelation of different higher twists entering into the expansion with opposite signs. This cancelation, found also in the proton moments, is a manifestation of the "duality" phenomenon in the F2 structure function.
Published: 2005

49. Deeply virtual and exclusive electroproduction of $\omega$-mesons

Author: Morand, L, Dore, D, Garcon, M, Guidal, M, Laget, Jm, Morrow, S, Sabatie, F, Smith, E, Adams, G, Arnbrozewicz, P, Anghinolfi, Marco, Asryan, G, Audit, G, Avakian, H, Bagdasaryan, H, Ball, J, Ball, Jp, Baltzell, Na, Barrow, S, Batourine, V, Battaglieri, Marco, Bektasoglu, M, Bellis, M, Benmouna, N, Berman, Bl, Biselli, As, Boiarinov, S, Bonner, Be, Bouchigny, S, Bradford, R, Branford, D, Briscoe, Wj, Brooks, Wk, Bultmann, S, Burkert, Vd, Butuceanu, C, Calarco, Jr, Careccia, Sl, Carman, Ds, Cazes Antoine Jacques, Chen, S, Cole, Pl, Cords, D, Corvisiero, Pietro, Crabb, D, Cummings, Jp, De Sanctis Enzo, Devita, R, Degtyarenko, Pv, Denizli, H, Dennis, L, Deur, A, Dharmawardane, Kv, Dhuga, Ks, Djalali, C, Dodge, Ge, Donnelly, J, Doughty, D, Dugger, M, Dytman, S, Dzyubak, Op, Egiyan, H, Egiyan, Ks, Elouadrhiri, L, Eugenio, P, Fatemi, R, Feldman, Gerald, Fersch, Rg, Feuerbach, Rj, Funsten, H, Gavalian, G, Gilfoyle, Gp, Giovanetti, Kl, Girod, Fx, Goetz, Jt, Gordon, Cio, Gothe, Rw, Griffioen, Ka, Guillo, M, Guler, N, Guo, L, Gyurjyan, V, Hadjidakis, Cynthia, Hakobyan, Rs, Hardie, J, Heddle, D, Hersman, Fw, Hicks, K, Hleiqawi, I, Holtrop, M, Hyde Wright CE, Ilieva, Y, Ireland, Dg, Ito, Mm, Jenkins, D, Jo, Hs, Joo, K, Juengst, Hg, Kellie, Jd, Khandaker, M, Kim, W, Klein, A, Klein, Fj, Klimenko, Av, Kossov, M, Kubarovski, V, Kramer, Lh, Kuhn, Se, Kuhn, J, Lachniet, J, Langhenirich, J, Lawrence, D, Lee, T, Jun, Li, Livingston, K, Marchand, C, Maximon, Lc, Mcaleer, S, Mckinnon, B, Mcnabb, Jwc, Mecking, Ba, Mehrabyan, S, Melone, Jj, Mestayer, Md, Meyer, Ca, Mikhailov, K, Minehart, R, Mirazita, Marco, Miskimen, R, Mokeev, V, Mueller, J, Mutchler, Gs, Napolitano, J, Nasseripour, R, Niccolai, S, Niculescu, G, Niculescu, I, Niczyporuk, Bb, Niyazov, Ra, Nozar, M, O'Rielly, Gv, Osipenko, Mikhail, Ostrovidov, Ai, Park, K, Pasyuk, E, Philips, Sa, Pivnyuk, N, Pocanic, D, Pogorelko, O, Polli, Ermanno, Popa, I, Pozdniakov, S, Preedom, Bm, Price, Jw, Prok, Y, Protopopescu, D, Raue, Ba, Riccardi, G, Ricco, Giovanni, Ripani, Marco, Ritchie, Bg, Ronchetti, Federico, Rosner, G, Rossi, Patrizia, Rubin, Pd, Salgado Lopez Carlos Alberto, Santoro, Joseph, Sapunenko, Vladimir, Schumacher, Ra, Serov, Vs, Sharabian, Yg, Shaw, J, Skabelin, Av, Smith, Lc, Sober, Di, Stavinsky, A, Stepanyan, S, Stepanyan, Ss, Stokes, Be, Stoler, P, Strakovsky, Ii, Strauch, S, Taiuti, MAURO GINO, Tedeschi, Dj, Thoma, U, Tkabladze, A, Todor, L, Tur, C, Ungaro, M, Vineyard, Mf, Vlassov, Av, Weinstein, Lb, Weygand, Dp, Williams Meurig Crispin Stowe, Wolin, E, Wood, Mh, Yegneswaran, A, Zana, L., Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and CLAS
Subjects: Nuclear and High Energy Physics, Particle physics, Photon, Meson, Proton, Nuclear Theory, FOS: Physical sciences, Parton, 13.60.Le - 12.40.Nn -12.38.Bx, 01 natural sciences, Omega, Resonance (particle physics), High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), GENERALIZED PARTON DISTRIBUTIONS, CLAS, 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], SCATTERING, 010306 general physics, Nuclear Experiment, Coupling, Physics, 010308 nuclear & particles physics, HYDROGEN, PHOTON, SPIN, GENERALIZED PARTON DISTRIBUTIONS, VECTOR-MESONS, SCATTERING, PHOTON, HYDROGEN, SPIN, CLAS, High Energy Physics::Experiment, Nucleon, VECTOR-MESONS
Abstract: The exclusive omega electroproduction off the proton was studied in a large kinematical domain above the nucleon resonance region and for the highest possible photon virtuality (Q2) with the 5.75 GeV beam at CEBAF and the CLAS spectrometer. Cross sections were measured up to large values of the four-momentum transfer (-t < 2.7 GeV2) to the proton. The contributions of the interference terms sigma_TT and sigma_TL to the cross sections, as well as an analysis of the omega spin density matrix, indicate that helicity is not conserved in this process. The t-channel pi0 exchange, or more generally the exchange of the associated Regge trajectory, seems to dominate the reaction gamma* p -> omega p, even for Q2 as large as 5 GeV2. Contributions of handbag diagrams, related to Generalized Parton Distributions in the nucleon, are therefore difficult to extract for this process. Remarkably, the high-t behaviour of the cross sections is nearly Q2-independent, which may be interpreted as a coupling of the photon to a point-like object in this kinematical limit., 15 pages,19 figures
Published: 2005

50. First observation of in-medium modifications of the omega meson

Author: Trnka, D., Anton, G., Bacelar, J.C.S, Bartholomy, O., Bayadilov, D., Beloglazov, Y.A., Bogendorfer, R., Castelijns, R.J.J., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Ewald, R., Fabry, I., Fuchs, M., Essig, K., Funke, Ch., Gothe, R., Gregor, R., Gridnev, A., Gutz, E., Hoffgen, S.K., Hoffmeister, P., Horn, I., Hössl, J., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Klein, Frank, Klein, Fritz, Klempt, E., Konrad, M., Kopf, B., Kotulla, M., Krusche, B., Langheinrich, J., Löhner, H., Lopatin, I., Lotz, J., Lugert, S., Menze, D.W., Messchendorp, J.G., Mertens, T., Metag, V., Morales, C., Nanova, M., Novotny, R., Ostrick, M., Pant, L.M., van Pee, H., Pfeiffer, M., Roy, A., Radkov, A., Schadmand, S., Schmidt, Ch., Schmieden, H., Schoch, B., Shende, S., Suft, G., Sumachev, V., Szczepanek, T., Sule, A., Thoma, U., Varma, R., Walther, D., Weinheimer, Ch., Wendel, Ch., and KVI - Center for Advanced Radiation Technology
Subjects: JONA-LASINIO MODEL, deuteron, +pi0+photon%22">omega(783) --> pi0 photon, Nuclear Theory, FOS: Physical sciences, (pi0 photon) [mass spectrum], +omega%28783%29+anything%22">photon nucleus --> omega(783) anything, 0.64-2.53 GeV, High Energy Physics - Experiment, Nuclear Theory (nucl-th), High Energy Physics - Experiment (hep-ex), ddc:550, Bonn ELSA Stor, SPECTROMETER, density [nuclear matter], Nuclear Experiment (nucl-ex), Nuclear Experiment, AU COLLISIONS, mass [omega(783)], NUCLEI, PAIRS, momentum [omega(783)], radiative decay [omega(783)], High Energy Physics::Experiment, photoproduction [omega(783)], inclusive reaction [photon nucleus], NAMBU, niobium, VECTOR-MESONS, MATTER, experimental results
Abstract: The photoproduction of omega mesons on nuclei has been investigated using the Crystal Barrel/TAPS experiment at the ELSA tagged photon facility in Bonn. The aim is to study possible in-medium modifications of the omega meson via the reaction A(gamma, omega)X. Results obtained for Nb are compared to a reference measurement on a liquid hydrogen target. While for recoiling, long-lived mesons (pi, eta and etaprime), which decay outside of the nucleus, a difference in the lineshape for the two data samples is not observed, we find a significant enhancement towards lower masses for omega mesons with low momenta produced on the Nb target., Comment: Latex, 4 pages, 4 figures, accepted by Phys. Rev. Lett; references re-arranged, now references in chronological order in first paragraph
Published: 2005
Full Text: View/download PDF

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

Database

Publisher

63 results on '"Thoma, U"'

Search Results

Catalog

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources