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13 results on '"Širca, S."'

1. Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

Author

Christy, M.E., Gautam, T., Ou, L., Schmookler, B., Wang, Y., Adikaram, D., Ahmed, Z., Albataineh, H., Ali, S.F., Aljawrneh, B., Allada, K., Allison, S.L., Alsalmi, S., Androic, D., Aniol, K., Annand, John, Arrington, J., Atac, H., Averett, T., Ayerbe Gayoso, C., Bai, X., Bane, J., Barcus, S., Bartlett, K., Bellini, V., Beminiwattha, R., Bericic, J., Bhatt, H., Bhetuwal, D., Biswas, D., Brash, E., Bulumulla, D., Camacho, C.M., Campbell, J., Camsonne, A., Carmignotto, M., Castellanos, J., Chen, C., Chen, J-P., Chetry, T., Cisbani, E., Clary, B., Cohen, E., Compton, N., Cornejo, J.C., Covrig Dusa, S., Crowe, B., Danagoulian, S., Danley, T., Deconinck, W., Defurne, M., Desnault, C., Di, D., Dlamini, M., Duer, M., Duran, B., Ent, R., Fanelli, C., Fuchey, E., Gal, C., Gaskell, D., Georges, F., Gilad, S., Glamazdin, O., Gnanvo, K., Gramolin, A.V., Gray, V.M., Gu, C., Habarakada, A., Hague, T., Hamad, G., Hamilton, David, Hamilton, K., Hansen, O., Hauenstein, F., Hernandez, A.V., Henry, W., Higinbotham, D.W., Holmstrom, T., Horn, T., Huang, Y., Huber, G.M., Hyde, C., Ibrahim, H., Israel, N., Jen, C-M., Jin, K., Jones, M., Kabir, A., Karki, B., Keppel, C., Khachatryan, V., King, P.M., Li, S., Li, W., Liu, H., Liu, J., Liyanage, A.H., Mack, D., Magee, J., Malace, S., Mammei, J., Markowitz, P., Mayilyan, S., McClellan, E., Meddi, F., Meekins, D., Mesick, K., Michaels, R., Mkrtchyan, A., Moffit, B., Montgomery, Rachel, Myers, L.S., Nadel-Turonski, P., Nazeer, S.J., Nelyubin, V., Nguyen, D., Nuruzzaman, N., Nycz, M., Obrecht, R.F., Ohanyan, K., Palatchi, C., Pandey, B., Park, K., Park, S., Peng, C., Persio, F.D., Pomatsalyuk, R., Pooser, E., Puckett, A.J.R., Punjabi, V., Quinn, B., Rahman, S., Rashad, M.N.H., Reimer, P.E., Riordan, S., Roche, J., Sapkota, I., Sarty, A., Sawatzky, B., Saylor, N.H., Shabestari, M.H., Shahinyan, A., Širca, S., Smith, G.R., Sooriyaarachchilage, S., Sparveris, N., Spies, R., Stefanko, A., Su, T., Subedi, A., Sulkosky, V., Sun, A., Tan, Y., Thorne, L., Ton, N., Tortorici, F., Trotta, R., Uniyal, R., Urciuoli, G.M., Voutier, E., Waidyawansa, B., Wojtsekhowski, B., Wood, S., Yan, X., Ye, L., Ye, Z.H., Yero, C., Zhang, J., Zhao, Y.X., Zhu, P., 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), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), CentraleSupélec, 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
exchange: two-photon, polarization, longitudinal, momentum transfer, p: form factor: magnetic, FOS: Physical sciences, General Physics and Astronomy, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], form factor, electron-proton scattering, two photon exchange, High Energy Physics - Experiment, electron p: scattering, High Energy Physics - Experiment (hep-ex), transverse, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment (nucl-ex), cross section: elastic scattering, Nuclear Experiment
Abstract

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q$^2$) up to 15.75~\gevsq. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q$^2$ and double the range over which a longitudinal/transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q$^2$ and attributed to hard two-photon exchange (TPE) effects, extending to 8~(GeV/c)$^2$ the range of Q$^2$ for which a discrepancy is established at $>$95\% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q$^2$., 7 pages, 2 figures

Published
2022

2. Dispersive Corrections to the Born Approximation in Elastic Electron-Nucleus Scattering in the Intermediate Energy Regime

Author

Guèye, P., Kabir, A.A., Glister, J., Lee, B.W., Gilman, R., Higinbotham, D.W., Piasetzky, E., Ron, G., Sarty, A.J., Strauch, S., Adeyemi, A., Allada, K., Armstrong, W., Arrington, J., Arenhövel, H., Beck, A., Benmokhtar, F., Berman, B.L., Boeglin, W., Brash, E., Camsonne, A., Calarco, J., Chen, J.P., Choi, S., Chudakov, E., Coman, L., Craver, B., Cusanno, F., Dumas, J., Dutta, C., Feuerbach, R., Freyberger, A., Frullani, S., Garibaldi, F., Hansen, J.-O., Holmstrom, T., Hyde, C.E., Ibrahim, H., Ilieva, Y., Jiang, X., Jones, M.K., Katramatou, A.T., Kelleher, A., Khrosinkova, E., Kuchina, E., Kumbartzki, G., LeRose, J.J., Lindgren, R., Markowitz, P., May-Tal Beck, S., Mccullough, E., Meekins, D., Meziane, M., Meziani, Z.-E., Michaels, R., Moffit, B., Norum, B.E., Petratos, G.G., Oh, Y., Olson, M., Paolone, M., Paschke, K., Perdrisat, C.F., Potokar, M., Pomatsalyuk, R., Pomerantz, I., Puckett, A., Punjabi, V., Qian, X., Qiang, Y., Ransome, R.D., Reyhan, M., Roche, J., Rousseau, Y., Sawatzky, B., Schulte, E., Schwamb, M., Shabestari, M., Shahinyan, A., Shneor, R., Širca, S., Slifer, K., Solvignon, P., Song, J., Sparks, R., Subedi, R., Urciuoli, G.M., Wang, K., Wojtsekhowski, B., Yan, X., Yao, H., Zhan, X., Zhu, X., Laboratoire de Physique de Clermont (LPC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS), and Jefferson Lab Hall A

Subjects
Nuclear Theory (nucl-th), Nuclear Theory, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], FOS: Physical sciences, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

Measurements of elastic electron scattering data within the past decade have highlighted two-photon exchange contributions as a necessary ingredient in theoretical calculations to precisely evaluate hydrogen elastic scattering cross sections. This correction can modify the cross section at the few percent level. In contrast, dispersive effects can cause significantly larger changes from the Born approximation. The purpose of this experiment is to extract the carbon-12 elastic cross section around the first diffraction minimum, where the Born term contributions to the cross section are small to maximize the sensitivity to dispersive effects. The analysis uses the LEDEX data from the high resolution Jefferson Lab Hall A spectrometers to extract the cross sections near the first diffraction minimum of 12C at beam energies of 362 MeV and 685 MeV. The results are in very good agreement with previous world data, although with less precision. The average deviation from a static nuclear charge distribution expected from linear and quadratic fits indicate a 30.6% contribution of dispersive effects to the cross section at 1 GeV. The magnitude of the dispersive effects near the first diffraction minimum of 12C has been confirmed to be large with a strong energy dependence and could account for a large fraction of the magnitude for the observed quenching of the longitudinal nuclear response. These effects could also be important for nuclei radii extracted from parity-violating asymmetries measured near a diffraction minimum., Comment: 14 pages, 10 figures

Published
2018

3. Polarization Transfer Observables in Elastic Electron Proton Scattering at $Q^2 = $2.5, 5.2, 6.8, and 8.5 GeV$^2$

Author

Puckett, A.J.R., Brash, E.J., Jones, M.K., Luo, W., Meziane, M., Pentchev, L., Perdrisat, C.F., Punjabi, V., Wesselmann, F.R., Afanasev, A., Ahmidouch, A., Albayrak, I., Aniol, K.A., Arrington, J., Asaturyan, A., Baghdasaryan, H., Benmokhtar, F., Bertozzi, W., Bimbot, L., Bosted, P., Boeglin, W., Butuceanu, C., Carter, P., Chernenko, S., Christy, E., Commisso, M., Cornejo, J.C., Covrig, S., Danagoulian, S., Daniel, A., Davidenko, A., Day, D., Dhamija, S., Dutta, D., Ent, R., Frullani, S., Fenker, H., Frlez, E., Garibaldi, F., Gaskell, D., Gilad, S., Gilman, R., Goncharenko, Y., Hafidi, K., Hamilton, D., Higinbotham, D.W., Hinton, W., Horn, T., Hu, B., Huang, J., Huber, G.M., Jensen, E., Keppel, C., Khandaker, M., King, P., Kirillov, D., Kohl, M., Kravtsov, V., Kumbartzki, G., Li, Y., Mamyan, V., Margaziotis, D.J., Marsh, A., Matulenko, Y., Maxwell, J., Mbianda, G., Meekins, D., Melnik, Y., Miller, J., Mkrtchyan, A., Mkrtchyan, H., Moffit, B., Moreno, O., Mulholland, J., Narayan, A., Nedev, S., Nuruzzaman, N., Piasetzky, E., Pierce, W., Piskunov, N.M., Prok, Y., Ransome, R.D., Razin, D.S., Reimer, P., Reinhold, J., Rondon, O., Shabestari, M., Shahinyan, A., Shestermanov, K., Širca, S., Sitnik, I., Smykov, L., Smith, G., Solovyev, L., Solvignon, P., Subedi, R., Tomasi-Gustafsson, E., Vasiliev, A., Veilleux, M., Wojtsekhowski, B.B., Wood, S., Ye, Z., Zanevsky, Y., Zhang, X., Zhang, Y., Zheng, X., Zhu, 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), 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, 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
Born approximation, generalized parton distribution, electron: trajectory, FOS: Physical sciences, Newport News CEBAF Linac, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], spin, bremsstrahlung, electron p: elastic scattering, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), hydrogen: liquid: target, quark: constituent, p: form factor: ratio, quantum chromodynamics, radiative correction, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], p: polarization, p: recoil, angular distribution, Nuclear Experiment (nucl-ex), electron: beam, Nuclear Experiment, background: suppression, lattice field theory, helicity, vector meson, time projection chamber, Dyson-Schwinger equation, calorimeter: electromagnetic, experimental equipment, analyzing power, asymmetry, Jefferson Lab, experimental results
Abstract

The GEp-III and GEp-2$\gamma$ experiments were carried out in Jefferson Lab's (JLab's) Hall C from 2007-2008, to extend the knowledge of $G_E^p/G_M^p$ to the highest practically achievable $Q^2$ and to search for effects beyond the Born approximation in polarization transfer observables of elastic $\vec{e}p$ scattering. This article reports an expanded description of the common experimental apparatus and data analysis procedure, and the results of a final reanalysis of the data from both experiments, including the previously unpublished results of the full-acceptance data of the GEp-2$\gamma$ experiment. The Hall C High Momentum Spectrometer detected and measured the polarization of protons recoiling elastically from collisions of JLab's polarized electron beam with a liquid hydrogen target. A large-acceptance electromagnetic calorimeter detected the elastically scattered electrons in coincidence to suppress inelastic backgrounds. The final GEp-III data are largely unchanged relative to the originally published results. The statistical uncertainties of the final GEp-2$\gamma$ data are significantly reduced at $\epsilon = 0.632$ and $0.783$ relative to the original publication. The decrease with $Q^2$ of $G_E^p/G_M^p$ continues to $Q^2 = 8.5$ GeV$^2$, but at a slowing rate relative to the approximately linear decrease observed in earlier Hall A measurements. At $Q^2 = 2.5$ GeV$^2$, the proton form factor ratio $G_E^p/G_M^p$ shows no statistically significant $\epsilon$-dependence, as expected in the Born approximation. The ratio $P_\ell/P_\ell^{Born}$ of the longitudinal polarization transfer component to its Born value shows an enhancement of roughly 1.4\% at $\epsilon = 0.783$ relative to $\epsilon = 0.149$, with $\approx 1.9\sigma$ significance based on the total uncertainty, implying a similar effect in the transverse component $P_t$ that cancels in the ratio $R$., Comment: 44 pages, 28 figures. Archival publication for the GEp-III and GEp-2gamma experiments that ran in Jefferson Lab's experimental Hall C from October, 2007 to June, 2008. v2: final manuscript as accepted by PRC. v3: Replaced figures 13 and 19 with corrected versions from published Erratum. Also made minor corrections to the text and to Table XI reflecting the corrections in the published Erratum

Published
2017

4. First measurement of unpolarized semi-inclusive deep-inelastic scattering cross sections from a $^3$He target

Author

Allada, K., Aniol, K., Annand, J.R.M., Averett, T., Benmokhtar, F., Bertozzi, W., Bradshaw, P.C., Bosted, P., Camsonne, A., Canan, M., Cates, G.D., Chen, C., Chen, J.-P., Chen, W., Chirapatpimol, K., Chudakov, E., Cisbani, E., Cornejo, J.C., Cusanno, F., Dalton, M.M., Deconinck, W., de Jager, C.W., de Leo, R., Deng, X., Deur, A., Ding, H., Dolph, P.A.M., Dutta, C., Dutta, D., El Fassi, L., Frullani, S., Gao, H., Garibaldi, F., Gaskell, D., Gilad, S., Gilman, R., Glamazdin, O., Golge, S., Guo, L., Hamilton, D., Hansen, O., Higinbotham, D.W., Holmstrom, T., Huang, J., Huang, M., Ibrahim, H.F., Iodice, M., Jiang, X., Jin, G., Jones, M.K., Katich, J., Kelleher, A., Kim, W., Kolarkar, A., Korsch, W., Lerose, J.J., Li, X., Li, Y., Lindgren, R., Liu, T., Liyanage, N., Long, E., Lu, H.-J., Margaziotis, D.J., Markowitz, P., Marrone, S., Mcnulty, D., Meziani, Z.-E., Michaels, R., Moffit, B., Muñoz Camacho, C., Nanda, S., Narayan, A., Nelyubin, V., Norum, B., Oh, Y., Osipenko, M., Parno, D., Peng, J.-C., Phillips, S.K., Posik, M., Puckett, A.J.R., Qian, X., Qiang, Y., Rakhman, A., Ransome, R., Riordan, S., Saha, A., Sawatzky, B., Schulte, E., Shahinyan, A., Shabestari, M.H., Širca, S., Stepanyan, S., Subedi, R., Sulkosky, V., Tang, L.-G., Tobias, W.A., Urciuoli, G.M., Vilardi, I., Wang, K., Wojtsekhowski, B., Wang, Y., Yan, X., Yao, H., Ye, Y., Ye, Z., Yuan, L., Zhan, X., Zhang, Y.-W., Zhao, B., Zhao, Y.X., Zheng, X., Zhu, L., Zhu, X., Zong, X., Laboratoire de Physique de Clermont ( LPC ), Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Université Clermont Auvergne ( UCA ) -Centre National de la Recherche Scientifique ( CNRS ), Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ), Jefferson Lab Hall A, Laboratoire de Physique de Clermont (LPC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)

Subjects
+electron+pi%2B%22">electron helium --> electron pi+, HRS, helium: target, cross section: ratio, plane wave, HERMES, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], cross section: angular dependence, COMPASS, Sivers function, quantum chromodynamics, electron: beam, [ PHYS.NEXP ] Physics [physics]/Nuclear Experiment [nucl-ex], +electron+pi%22">electron helium --> electron pi, deep inelastic scattering: semi-inclusive reaction, nucleus, parametrization, showers, model: quark parton, pi+: production, kinematics, differential cross section, quark: valence, higher-dimensional, numerical calculations: Monte Carlo, experimental results, Jefferson Lab
Abstract

International audience; The unpolarized semi-inclusive deep-inelastic scattering (SIDIS) differential cross sections in He3(e,e′π±)X have been measured for the first time in Jefferson Lab experiment E06-010 with a 5.9GeVe− beam on a He3 gas target. The experiment focuses on the valence quark region, covering a kinematic range 0.12

Published
2017

5. Ground-state binding energy of $^4_s$H from high-resolution decay-pion spectroscopy

Author

Schulz, F., Achenbach, P., Aulenbacher, S., Beričič, J., Bleser, S., Böhm, R., Bosnar, D., Correa, L., Distler, M.O., Esser, A., Fonvieille, H., Friščić, I., Fujii, Y., Fujita, M., Gogami, T., Kanda, H., Kaneta, M., Kegel, S., Kohl, Y., Kusaka, W., Margaryan, A., Merkel, H., Mihovilovič, M., Müller, U., Nagao, S., Nakamura, S.N., Pochodzalla, J., Sanchez Lorente, A., Schlimme, B.S., Schoth, M., Sfienti, C., Širca, S., Steinen, M., Takahashi, Y., Tang, L., Thiel, M., Tsukada, K., Tyukin, A., Weber, A., Laboratoire de Physique de Clermont (LPC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), A1, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Charge symmetry breaking, Hypernuclear mass spectroscopy, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Mesonic weak decay
Abstract

International audience; A systematic study on the Λ ground state binding energy of hyperhydrogen HΛ4 measured at the Mainz Microtron MAMI is presented. The energy was deduced from the spectroscopy of mono-energetic pions from the two-body decays of hyperfragments, which were produced and stopped in a 9 Be target. First data, taken in the year 2012 with a high resolution magnetic spectrometer, demonstrated an almost one order of magnitude higher precision than emulsion data, while being limited by systematic uncertainties. In 2014 an extended measurement campaign was performed with improved control over systematic effects, increasing the yield of hypernuclei and confirming the observation with two independent spectrometers and two targets of different thicknesses. The analysis of these data is in agreement with the previously published value for the HΛ4 binding energy as well as with a consistent re-analysis of the 2012 data. When compared to the HeΛ4 binding energy from emulsion data, a large charge symmetry breaking effect in the A=4 hypernuclear system is confirmed.

Published
2016

6. Precision Measurement of the p(e,e′p)π0 Reaction at Threshold

Author

Chirapatpimol, K., Shabestari, M.H., Lindgren, R.A., Smith, L.C., Annand, J.R.M., Higinbotham, D.W., Moffit, B., Nelyubin, V., Norum, B.E., Allada, K., Aniol, K., Ardashev, K., Armstrong, D.S., Arndt, R.A., Benmokhtar, F., Bernstein, A.M., Bertozzi, W., Briscoe, W.J., Bimbot, L., Camsonne, A., Chen, J.-P., Choi, S., Chudakov, E., Cisbani, E., Cusanno, F., Dalton, M.M., Dutta, C., Egiyan, K., Fernàndez-Ramìrez, C., Feuerbach, R., Fissum, K.G., Frullani, S., Garibaldi, F., Gayou, O., Gilman, R., Gilad, S., Goity, J., Gomez, J., Hahn, B., Hamilton, D., Hansen, J.-O., Huang, J., Igarashi, R., Ireland, D., De Jager, C.W., Jin, X., Jiang, X., Jinasundera, T., Kellie, J., Keppel, C.E., Kolb, N., LeRose, J., Liyanage, N., Livingston, K., McNulty, D., Mercado, L., Michaels, R., Mihovilovič, M., Qian, S., Qian, X., Mailyan, S., Mamyan, V., Marrone, S., Monaghan, P., Nanda, S., Perdrisat, C.F., Piasetzky, E., Protopopescu, D., Punjabi, V., Qiang, Y., Rachek, I.A., Rakhman, A., Riordan, S., Ron, G., Rosner, G., Saha, A., Sawatzky, B., Shahinyan, A., Širca, S., Sparveris, N., Subedi, R.R., Suleiman, R., Strakovsky, I., Sulkosky, V., Moinelo, J., Voskanyan, H., Wang, K., Wang, Y., Watson, J., Watts, D., Wojtsekhowski, B., Workman, R.L., Yao, H., Zhan, X., Zhang, Y., 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), and Hall A Collaboration

Subjects
[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

International audience; New results are reported from a measurement of π0 electroproduction near threshold using the p(e,e′p)π0 reaction. The experiment was designed to determine precisely the energy dependence of s- and p-wave electromagnetic multipoles as a stringent test of the predictions of chiral perturbation theory (ChPT). The data were taken with an electron beam energy of 1192 MeV using a two-spectrometer setup in Hall A at Jefferson Lab. For the first time, complete coverage of the ϕ∗π and θ∗π angles in the pπ0 center of mass was obtained for invariant energies above threshold from 0.5 up to 15 MeV. The 4-momentum transfer Q2 coverage ranges from 0.05 to 0.155 (GeV/c)2 in fine steps. A simple phenomenological analysis of our data shows strong disagreement with p-wave predictions from ChPT for Q2>0.07 (GeV/c)2, while the s-wave predictions are in reasonable agreement.

Published
2015

7. Measurement of the Neutron Electric to Magnetic Form Factor Ratio at Q2=1.58 GeV2 Using the Reaction He−→3(e⃗ ,e′n)pp

Author

Schlimme, B.S., Achenbach, P., Ayerbe Gayoso, C. A., Bernauer, J. C., Böhm, R., Bosnar, D., Challand, T., Distler, M.O., Doria, L., Fellenberger, F., Fonvieille, H., Gómez Rodríguez, M., Grabmayr, P., Hehl, T., Heil, W., Kiselev, D., Krimmer, J., Makek, M., Merkel, H., Middleton, D. G., Müller, U., Nungesser, L., Ott B., A., Pochodzalla, J., Potokar, M., Sánchez Majos, S., Sargsian M., M., Sick, I., Širca, S., Weinriefer, M., Wendel, M., Yoon, J., Institut für Kernphysik, Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University (JGU), Department of Physics [Zagreb], Faculty of Science [Zagreb], University of Zagreb-University of Zagreb, Department of Physics, University of Basel (Unibas), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Physikalisches Institut [Tübingen], Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, Institut für Physik [Mainz], The Swiss Light Source (SLS) (SLS-PSI), Paul Scherrer Institute (PSI), Institut de Physique Nucléaire de Lyon (IPNL), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Jozef Stefan Institute [Ljubljana] (IJS), Florida International University [Miami] (FIU), University of Ljubljana, Johannes Gutenberg - Universität Mainz (JGU), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
High Energy Physics::Experiment, Nuclear Experiment
Abstract

International audience; A measurement of beam helicity asymmetries in the reaction He−→3(e⃗ ,e′n)pp is performed at the Mainz Microtron in quasielastic kinematics to determine the electric to magnetic form factor ratio of the neutron GnE/GnM at a four-momentum transfer Q2=1.58 GeV2. Longitudinally polarized electrons are scattered on a highly polarized He3 gas target. The scattered electrons are detected with a high-resolution magnetic spectrometer, and the ejected neutrons are detected with a dedicated neutron detector composed of scintillator bars. To reduce systematic errors, data are taken for four different target polarization orientations allowing the determination of GnE/GnM from a double ratio. We find μnGnE/GnM=0.250±0.058(stat)±0.017(syst).

Published
2013

8. Search for light gauge bosons of the dark sector at MAMI

Author

Merkel, H., Achenbach, P., Gayoso, C. Ayerbe, Bernauer, J. C., Böhm, R., Bosnar, D., Debenjak, L., Denig, A., Distler, M. O., Esser, A., Fonvieille, H., Friščić, I., Middleton, D. G., Müller, U., Nungesser, L., Pochodzalla, J., Rohrbeck, M., Majos, S. Sánchez, Schlimme, B. S., Schoth, M., Širca, S., Weinriefer, M., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and MAMI-A1

Subjects
High Energy Physics::Phenomenology, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, 95.30.Cq, 14.70.Pw, 25.30.Rw
Abstract

4 pages, 7 figures, soumis à PRL; A new exclusion limit for the electromagnetic production of a light U(1) gauge boson {\gamma}' decaying to e^+e^- was determined by the A1 Collaboration at the Mainz Microtron MAMI. Such light gauge bosons appear in several extensions of the standard model and are also discussed as candidates for the interaction of dark matter with Standard Model matter. In electron scattering from a heavy nucleus, the existing limits for a narrow state coupling to e^+e^- were reduced by nearly an order of magnitude in the range of the lepton pair mass of 210 MeV/c^2 < m_e^+e^- < 300 MeV/c^2. This experiment demonstrates the potential of high current and high resolution fixed target experiments for the search for physics beyond the Standard Model.

Published
2011

9. First measurements of Lambda and Sigma0 hyperons in elementary electroproduction at MAMI

Author

Achenbach, P., Ayerbe Gayoso, C., Bernauer, J.C., Bianchin, S., Böhm, R., Borodina, O., Bosnar, D., Bozkurt, V., Debenjak, L., Denig, A., Distler, M.O., Essera, A., Fonvieille, H., Friščić, I., Göküzüm, B., Grießinger, K., Kim, E., Maas, F.E., Makek, M., Merkel, H., Minami, S., Müller, U., Nakajima, D., Nungesser, L., Özel-Tashenov, B., Pochodzalla, J., Potokar, M., Rappold, Ch., Saito, T.R., Sánchez Majos, S., Schlimme, B.S., Širca, S., Weinriefera, M., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and MAMI-A1

Subjects
Missing mass spectroscopy, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Electroproduction reactions, Kaon, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2009

10. A new measurement of the structure functions $P_{LL}-P_{TT}/epsilon$ and $P_{LT}$ in virtual Compton scattering at $Q^2=$ 0.33 (GeV/c)$^2$

Author

Collaboration, The MAMI-A1, Janssens, P., Doria, L., Achenbach, P., Gayoso, C. Ayerbe, Baumann, D., Bernauer, J. C., Bensafa, I. K., Böhm, R., Bosnar, D., Burtin, E., D'Hose, N., Defaÿ, X., Ding, M., Distler, M. O., Fonvieille, H., Friedrich, J., Friedrich, J. M., Laveissière, G., Makek, M., Marroncle, J., Merkel, H., Müller, U., Nungesser, L., Pasquini, B., Pochodzalla, J., Postavaru, O., Potokar, M., Ryckbosch, D., Majos, S. Sanchez, Schlimme, B. S., Seimetz, M., Širca, S., Tamas, G., Van de Vyver, R., Van Hoorebeke, L., Van Overloop, A., Walcher, Th., Weinriefer, M., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), 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, and MAMI-A1

Subjects
Physics, Nuclear and High Energy Physics, Proton, 010308 nuclear & particles physics, Detector, Structure function, Compton scattering, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, High Energy Physics - Experiment, Nuclear physics, Cross section (physics), High Energy Physics - Experiment (hep-ex), 0103 physical sciences, Cathode ray, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment (nucl-ex), 010306 general physics, Linear combination, elastic and compton scattering, protons and neutrons, electroproduction, Nuclear Experiment
Abstract

The cross section of the $ep \to e' p' \gamma$ reaction has been measured at $Q^2 = 0.33$ (GeV/c)$^2$. The experiment was performed using the electron beam of the MAMI accelerator and the standard detector setup of the A1 Collaboration. The cross section is analyzed using the low-energy theorem for virtual Compton scattering, yielding a new determination of the two structure functions $P_LL}-P_{TT}/epsilon$ and $P_{LT}$ which are linear combinations of the generalized polarizabilities of the proton. We find somewhat larger values than in the previous investigation at the same $Q^2$. This difference, however, is purely due to our more refined analysis of the data. The results tend to confirm the non-trivial $Q^2$-evolution of the generalized polarizabilities and call for more measurements in the low-$Q^2$ region ($\le$ 1 (GeV/c)$^2$)., Comment: 9 pages, 10 figures. EPJA version. slight revisions in the text and figures

Published
2008

11. Recoil Polarization Measurements for Neutral Pion Electroproduction at $Q^2$=1 (GeV/c)$^2$ Near the $\Delta$ Resonance

Author

Kelly, J.J., Gayou, O., E. Roché, R., Chai, Z., K. Jones, M., J. Sarty, A., Frullani, S., Aniol, K., J. Beise, E., Benmokhtar, F., Bertozzi, W., U. Boeglin, W., Botto, T., J. Brash, E., Breuer, H., Brown, E., Burtin, E., R. Calarco, J., Cavata, C., C. Chang, C., S. Chant, N., Chen, J.-P., Coman, M., Crovelli, D., De Leo, R., Dieterich, S., Escoffier, S., G. Fissum, K., Garde, V., Garibaldi, F., Georgakopoulos, S., Gilad, S., Gilman, R., Glashausser, C., Hansen, J.-O., W. Higinbotham, D., Hotta, A., M. Huber, G., Ibrahim, H., Iodice, M., W. De Jager, C., Jiang, X., Klimenko, A., Kozlov, A., Kumbartzki, G., Kuss, M., Lagamba, L., Laveissière, G., LeRose, J.J., A. Lindgren, R., Liyange, N., J. Lolos, G., W. Lourie, R., J. Margaziotis, D., Marie, F., Markowitz, P., McAleer, S., Meekins, D., Michaels, R., D. Milbrath, B., Mitchell, J., Nappa, J., Neyret, D., F. Perdrisat, C., Potokar, M., A. Punjabi, V., Pussieux, T., D. Ransome, R., G. Roos, P., Rvachev, M., Saha, A., Širca, S., Suleiman, R., Strauch, S., A. Templon, J., Todor, L., E. Ulmer, P., M. Urciuoli, G., B. Weinstein, L., Wijsooriya, K., Wojtsekhowski, B., Zheng, X., Zhu, L., Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and HALL A

Subjects
24.70.+s, 14.20.Gk, 13.60.Le, 13.40.Gp, FOS: Physical sciences, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

We measured angular distributions of differential cross section, beam analyzing power, and recoil polarization for neutral pion electroproduction at Q^2 = 1.0 (GeV/c)^2 in 10 bins of W across the Delta resonance. A total of 16 independent response functions were extracted, of which 12 were observed for the first time. Comparisons with recent model calculations show that response functions governed by real parts of interference products are determined relatively well near 1.232 GeV, but variations among models is large for response functions governed by imaginary parts and for both increases rapidly with W. We performed a nearly model-independent multipole analysis that adjusts complex multipoles with high partial waves constrained by baseline models. Parabolic fits to the W dependence of the multipole analysis around the Delta mass gives values for SMR = (-6.61 +/- 0.18)% and EMR = (-2.87 +/- 0.19)% that are distinctly larger than those from Legendre analysis of the same data. Similarly, the multipole analysis gives Re(S0+/M1+) = (+7.1 +/- 0.8)% at W=1.232 GeV, consistent with recent models, while the traditional Legendre analysis gives the opposite sign because its truncation errors are quite severe. Finally, using a unitary isobar model (UIM), we find that excitation of the Roper resonance is dominantly longitudinal with S1/2 = (0.05 +/- 0.01) GeV^(-1/2) at Q^2=1. The ReS0+ and ReE0+ multipoles favor pseudovector coupling over pseudoscalar coupling or a recently proposed mixed-coupling scheme, but the UIM does not reproduce the imaginary parts of 0+ multipoles well., Comment: 60 pages, 54 figures

Published
2007

12. Recoil polarization and beam-recoil double polarization measurement of $\eta$ electroproduction on the proton in the region of the $S_{11}$(1535) resonance

Author

Merkel, H., Achenbach, P., Gayoso, C. A. Ayerbe, Bernauer, J. C., Böhm, R., Bosnar, D., Cheymol, B., Distler, M. O., Doria, L., Fonvieille, H., Friedrich, J., Janssens, P., Makek, M., Müller, U., Nungesser, L., Pochodzalla, J., Potokar, M., Majos, S. Sánchez, Schlimme, B. S., Širca, S., Tiator, L., Walcher, Th., Weinriefer, M., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
25.30.Rw, 13.60.Le, 14.20.Gk, Nuclear Theory, Electroproduction, Polarization, Meson, Resonances, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

The beam-recoil double polarization P_{x'}^h and P_{z'}^h and the recoil polarization P_{y'} were measured for the first time for the p(\vec{e},e'\vec{p})\eta reaction at a four-momentum transfer of Q^2=0.1 GeV^2/c^2 and a center of mass production angle of \theta = 120^\circ at MAMI C. With a center of mass energy range of 1500 MeV < W < 1550 MeV the region of the S_{11}(1535) and D_{13}(1520) resonance was covered. The results are discussed in the framework of a phenomenological isobar model (Eta-MAID). While P_{x'}^h and P_{z'}^h are in good agreement with the model, P_{y'} shows a significant deviation, consistent with existing photoproduction data on the polarized-target asymmetry., Comment: 4 pages, 1 figure

Published
2007

13. Measurements of the Proton Elastic-Form-Factor Ratio µpG $^{p}_{E}$/G $^{p}_{M}$ at Low Momentum Transfer

Author

Ron, G., Glister, J., Lee, B., Allada, K., Armstrong, W., Arrington, J., Beck, A., Benmokhtar, F., L. Berman, B., Boeglin, W., Brash, E., Camsonne, A., Calarco, J., P. Chen, J., Choi, S., Chudakov, E., Coman, L., Craver, B., Cusanno, F., Dumas, J., Dutta, C., Feuerbach, R., Freyberger, A., Frullani, S., Garibaldi, F., Gilman, R., Hansen, O., W. Higinbotham, D., Holmstrom, T., Hyde, C. E., Ibrahim, H., Ilieva, Y., W. De Jager, C., Jiang, X., K. Jones, M., Kang, H., Kelleher, A., Khrosinkova, E., Kuchina, E., Kumbartzki, G., LeRose, J.J., Lindgren, R., Markowitz, P., May-Tal Beck, S., Mccullough, E., Meekins, D., Meziane, M., Meziani, Z.-E., Michaels, R., Moffit, B., E. Norum, B., Oh, Y., Olson, M., Paolone, M., Paschke, K., F. Perdrisat, C., Piasetzky, E., Potokar, M., Pomatsalyuk, R., Pomerantz, I., Puckett, A., Punjabi, V., Qian, X., Qiang, Y., Ransome, R., Reyhan, M., Roche, J., Rousseau, Y., Saha, A., J. Sarty, A., Sawatzky, B., Schulte, E., Shabestari, M., Shahinyan, A., Shneor, R., Širca, S., Slifer, K., Solvignon, P., Song, J., Sparks, R., Subedi, R., Strauch, S., M. Urciuoli, G., Wang, K., Wojtsekhowski, B., Yan, X., Yao, H., Zhan, X., Zhu, X., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and HALL A

Subjects
14.20.Dh, 13.40.Gp, 24.70.+s, 25.30.Bf, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Published
2007

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