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1. Deeply virtual Compton scattering off the neutron

Author

Benali, M., Desnault, C., Mazouz, M., Ahmed, Z., Albataineh, H., Allada, K., Aniol, K. A., Bellini, V., Boeglin, W., Bertin, P., Brossard, M., Camsonne, A., Canan, M., Chandavar, S., Chen, C., Chen, J.-P., Defurne, M., de Jager, C. W., de Leo, R., Deur, A., El Fassi, L., Ent, R., Flay, D., Friend, M., Fuchey, E., Frullani, S., Garibaldi, F., Gaskell, D., Giusa, A., Glamazdin, O., Golge, S., Gomez, J., Hansen, O., Higinbotham, D., Holmstrom, T., Horn, T., Huang, J., Huang, M., Huber, G. M., Hyde, C. E., Iqbal, S., Itard, F., Kang, Ho., Kang, Hy., Kelleher, A., Keppel, C., Koirala, S., Korover, I., LeRose, J. J., Lindgren, R., Long, E., Magne, M., Mammei, J., Margaziotis, D. J., Markowitz, P., Martí Jiménez-Argüello, A., Meddi, F., Meekins, D., Michaels, R., Mihovilovic, M., Muangma, N., Muñoz Camacho, C., Nadel-Turonski, P., Nuruzzaman, N., Paremuzyan, R., Pomatsalyuk, R., Puckett, A., Punjabi, V., Qiang, Y., Rakhman, A., Rashad, M. N. H., Riordan, S., Roche, J., Russo, G., Sabatié, F., Saenboonruang, K., Saha, A., Sawatzky, B., Selvy, L., Shahinyan, A., Sirca, S., Solvignon, P., Sperduto, M. L., Subedi, R., Sulkosky, V., Sutera, C., Tobias, W. A., Urciuoli, G. M., Wang, D., Wojtsekhowski, B., Yao, H., Ye, Z., Zana, L., Zhan, X., Zhang, J., Zhao, B., Zhao, Z., Zheng, X., and Zhu, P.

Published
2020
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2. Probing for high-momentum protons in $^{4}\mathrm{He}$ via the $^{4}\mathrm{He}(e,{e}^{'}p)X$ reactions

Author

Iqbal, S., Benmokhtar, F., Ivanov, M., See, N., Aniol, K., Higinbotham, D.W., Boyd, C., Gadsby, A., Goodwill, J.S., Finton, D., Boyer, A., Gilad, S., Saha, A., Udias, J.M., Ye, Z., Solvignon, P., Aguilera, P., Ahmed, Z., Albataineh, H., Allada, K., Anderson, B., Anez, D., Annand, J., Arrington, J., Averett, T., Baghdasaryan, H., Bai, X., Beck, A., Beck, S., Bellini, V., Camsonne, A., Chen, C., Chen, J.-P., Chirapatpimol, K., Cisbani, E., Dalton, M.M., Daniel, A., Day, D., Deconinck, W., Defurne, M., Flay, D., Fomin, N., Friend, M., Frullani, S., Fuchey, E., Garibaldi, F., Gaskell, D., Gilman, R., Glamazdin, S., Gu, C., Guèye, P., Hanretty, C., Hansen, J.-O., Hashemi Shabestari, M., Huang, M., Jin, G., Kalantarians, N., Kang, H., Kelleher, A., Korover, I., Lerose, J., Leckey, J., Lindgren, R., Long, E., Mammei, J., Margaziotis, D.J., Markowitz, P., Meekins, D., Meziani, Z., Michaels, R., Mihovilovic, M., Muangma, N., Munoz Camacho, C., Norum, B., Nuruzzaman, M., Pan, K., Phillips, S., Piasetzky, E., Pomerantz, I., Posik, M., Punjabi, V., Qian, X., Qiang, Y., Qiu, X., Reimer, P.E., Rakhman, A., Riordan, S., Ron, G., Rondon-Aramayo, O., Selvy, L., Shahinyan, A., Shneor, R., Sirca, S., Slifer, K., Sparveris, N., Subedi, R., Sulkosky, V., Wang, D., Watson, J.W., Weinstein, L.B., Wojtsekhowski, B., Wood, S.A., Yaron, I., Zhan, X., Zhang, J., Zhang, Y.W., Zhao, B., Zheng, X., Zhu, P., Zielinski, R., 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), Laboratoire de Physique de Clermont (LPC), 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 Jefferson Lab Hall A

Subjects
[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th]
Abstract

International audience; Experimental cross sections for the He4(e,e′p)X reactions in the missing energy range from 0.017 to 0.022 GeV and up to a missing momentum of 0.632 GeV/c at xB=1.24 and Q2=2 (GeV/c)2 are reported. The data are compared to relativistic distorted-wave impulse approximation calculations for the He4(e,e′p)H3 channel. Significantly more events are observed for pm≥0.45 GeV/c than are predicted by the theoretical model, and striking fluctuations in the ratio of data to the theoretical model around pm=0.3GeV/c are possible signals of initial-state multinucleon correlations.

Published
2022
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3. Probing for high momentum protons in $^4$He via the $^4He(e,e'p)X$ reaction

Author

Iqbal, S., Benmokhtar, F., Ivanov, M., See, N., Aniol, K., Higinbotham, D. W., Boyd, C., Gadsby, A., Gilad, S., Saha, A., Udias, J. M., Goodwill, J. S., Finton, D., Boyer, A., Ye, Z., Solvignon, P., Aguilera, P., Ahmed, Z., Albataineh, H., Allada, K., Anderson, B., Anez, D., Annand, J., Arrington, J., Averett, T., Baghdasaryan, H., Bai, X., Beck, A., Beck, S., Bellini, V., Camsonne, A., Chen, C., Chen, J. -P., Chirapatpimol, K., Cisbani, E., Dalton, M. M., Daniel, A., Day, D., Deconinck, W., Defurne, M., Flay, D., Fomin, N., Friend, M., Frullani, S., Fuchey, E., Garibaldi, F., Gaskell, D., Gilman, R., Glamazdin, S., Gu, C., Gueye, P., Hanretty, C., Hansen, J. -O., Shabestari, M. Hashemi, Huang, M., Jin, G., Kalantarians, N., Kang, H., Kelleher, A., Korover, I., LeRose, J., Leckey, J., Lindgren, R., Long, E., Mammei, J., Margaziotis, D. J., Markowitz, P., Meekins, D., Meziani, Z., Michaels, R., Mihovilovic, M., Muangma, N., Camacho, C. Munoz, Norum, B., Nuruzzaman, Nuruzzaman, Pan, K., Phillips, S., Piasetzky, E., Pomerantz, I., Posik, M., Punjabi, V., Qian, X., Qiang, Y., Qiu, X., Reimer, P. E., Rakhman, A ., Riordan, S., Ron, G., Rondon-Aramayo, O., Selvy, L., Shahinyan, A., Shneor, R., Sirca, S., Slifer, K., Sparveris, N., Subedi, R., Sulkosky, V., Wang, D., Watson, J. W., Weinstein, L. B., Wojtsekhowski, B., Wood, S. A., Yaron, I., Zhan, X., Zhang, J., Zhang, Y. W., Zhao, B., Zheng, X., Zhu, P., Zielinski, R., 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), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Physique de Clermont (LPC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Jefferson Lab Hall A, 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 HEP, INSPIRE

Subjects
[PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

Experimental cross sections for the $^4He(e,e'p)X$ reaction up to a missing momentum of 0.632 GeV/$c$ at $x_B=1.24$ and $Q^2$=2(GeV/$c$)$^2$ are reported. The data are compared to Relativistic Distorted Wave Impulse Approximation(RDWIA) calculations for $^4He(e,e'p)^3H$ channel. Significantly more events in the triton mass region are measured for $p_{m}$$>$0.45 GeV/$c$ than are predicted by the theoretical model, suggesting that the effects of initial-state multi-nucleon correlations are stronger than expected by the RDWIA model., Submitted to PRC

Published
2021
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4. Rosenbluth separation of the $\pi^0$ Electroproduction Cross Section off the Neutron

Author

Mazouz, M., Ahmed, Z., Albataineh, H., Allada, K., Aniol, K.A., Bellini, V., Benali, M., Boeglin, W., Bertin, P., Brossard, M., Camsonne, A., Canan, M., Chandavar, S., Chen, C., Chen, J.P., Defurne, M., de Jager, C.W., de Leo, R., Desnault, C., Deur, A., El Fassi, L., Ent, R., Flay, D., Friend, M., Fuchey, E., Frullani, S., Garibaldi, F., Gaskell, D., Giusa, A., Glamazdin, O., Golge, S., Gomez, J., Hansen, O., Higinbotham, D., Holmstrom, T., Horn, T., Huang, J., Huang, M., Huber, G.M., Hyde, C.E., Iqbal, S., Itard, F., Kang, Ho., Kang, Hy., Kelleher, A., Keppel, C., Koirala, S., Korover, I., Lerose, J.J., Lindgren, R., Long, E., Magne, M., Mammei, J., Margaziotis, D.J., Markowitz, P., Martí Jiménez-Argüello, A., Meddi, F., Meekins, D., Michaels, R., Mihovilovic, M., Muangma, N., Muñoz Camacho, C., Nadel-Turonski, P., Nuruzzaman, N., Paremuzyan, R., Puckett, A., Punjabi, V., Qiang, Y., Rakhman, A., Rashad, M.N.H., Riordan, S., Roche, J., Russo, G., Sabatié, F., Saenboonruang, K., Saha, A., Sawatzky, B., Selvy, L., Shahinyan, A., Sirca, S., Solvignon, P., Sperduto, M.L., Subedi, R., Sulkosky, V., Sutera, C., Tobias, W.A., Urciuoli, G.M., Wang, D., Wojtsekhowski, B., Yao, H., Ye, Z., Zana, L., Zhan, X., Zhang, J., Zhao, B., Zhao, Z., Zheng, X., Zhu, P., 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), 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), Jefferson Lab Hall A, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS), 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), 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 ), 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 ), 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 Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
longitudinal, Nuclear Theory, n: structure function, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], momentum transfer dependence, electron n: scattering, High Energy Physics - Experiment, generalized parton distribution: transversity, [ PHYS.HEXP ] Physics [physics]/High Energy Physics - Experiment [hep-ex], hard exclusive electroproduction, recoil, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], polarization: transverse, [ PHYS.NEXP ] Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, mesons, flavor, generalized parton distributions, scattering, deuteron: structure function, +electron+deuteron+pi0%22">electron deuteron --> electron deuteron pi0, electron deuteron: deep inelastic scattering, nucleon: generalized parton distribution, photon: polarization, coherence, pi0: electroproduction, High Energy Physics::Experiment, experimental results
Abstract

We report the first longitudinal/transverse separation of the deeply virtual exclusive $\pi^0$ electroproduction cross section off the neutron and coherent deuteron. The corresponding four structure functions $d\sigma_L/dt$, $d\sigma_T/dt$, $d\sigma_{LT}/dt$ and $d\sigma_{TT}/dt$ are extracted as a function of the momentum transfer to the recoil system at $Q^2$=1.75 GeV$^2$ and $x_B$=0.36. The $ed \to ed\pi^0$ cross sections are found compatible with the small values expected from theoretical models. The $en \to en\pi^0$ cross sections show a dominance from the response to transversely polarized photons, and are in good agreement with calculations based on the transversity GPDs of the nucleon. By combining these results with previous measurements of $\pi^0$ electroproduction off the proton, we present a flavor decomposition of the $u$ and $d$ quark contributions to the cross section., Comment: 6 pages, 6 figures, Submitted to Phys. Rev. Lett

Published
2017
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5. Probing the Repulsive Core of the Nucleon-Nucleon Interaction via the He-4(e,e'pN) Triple-Coincidence Reaction

Author

Korover, I, Muangma, N, Hen, O, Shneor, R, Sulkosky, V, Kelleher, A, Gilad, S, Higinbotham, Dw, Piasetzky, E, Watson, Jw, Wood, Sa, Aguilera, P, Ahmed, Z, Albataineh, H, Allada, K, Anderson, B, Anez, D, Aniol, K, Annand, J, Armstrong, W, Arrington, J, Averett, T, Badman, T, Baghdasaryan, H, Bai, X, Beck, A, Beck, S, Bellini, Vincenzo, Benmokhtar, F, Bertozzi, W, Bittner, J, Boeglin, W, Camsonne, A, Chen, C, Chen, Jp, Chirapatpimol, K, Cisbani, E, Dalton, Mm, Daniel, A, Day, D, de Jager CW, De Leo, R, Deconinck, W, Defurne, M, Flay, D, Fomin, N, Friend, M, Frullani, S, Fuchey, E, Garibaldi, F, Gaskell, D, Gilman, R, Glamazdin, O, Gu, C, Gueye, P, Hamilton, D, Hanretty, C, Hansen, Jo, Shabestari, Mh, Holmstrom, T, Huang, M, Iqbal, S, Jin, G, Kalantarians, N, Kang, H, Khandaker, M, Lerose, J, Leckey, J, Lindgren, R, Long, E, Mammei, J, Margaziotis, Dj, Markowitz, P, Jimenez Arguello AM, Meekins, D, Meziani, Z, Michaels, R, Mihovilovic, M, Monaghan, P, Camacho, Cm, Norum, B, Pan, K, Phillips, S, Pomerantz, I, Posik, M, Punjabi, V, Qian, X, Qiang, Y, Qiu, X, Rakhman, A, Reimer, Pe, Riordan, S, Ron, G, Rondon Aramayo, O, Saha, A, Schulte, E, Selvy, L, Shahinyan, A, Sirca, S, Sjoegren, J, Slifer, K, Solvignon, P, Sparveris, N, Subedi, R, Tireman, W, Wang, D, Weinstein, Lb, Wojtsekhowski, B, Yan, W, Yaron, I, Ye, Z, Zhan, X, Zhang, J, Zhang, Y, Zhao, B, Zhao, Z, Zheng, X, Zhu, P, and Zielinski, R.

Published
2014

6. A glimpse of gluons through deeply virtual compton scattering on the proton.

Author

Defurne M, Jiménez-Argüello AM, Ahmed Z, Albataineh H, Allada K, Aniol KA, Bellini V, Benali M, Boeglin W, Bertin P, Brossard M, Camsonne A, Canan M, Chandavar S, Chen C, Chen JP, de Jager CW, de Leo R, Desnault C, Deur A, El Fassi L, Ent R, Flay D, Friend M, Fuchey E, Frullani S, Garibaldi F, Gaskell D, Giusa A, Glamazdin O, Golge S, Gomez J, Hansen O, Higinbotham D, Holmstrom T, Horn T, Huang J, Huang M, Hyde CE, Iqbal S, Itard F, Kang H, Kelleher A, Keppel C, Koirala S, Korover I, LeRose JJ, Lindgren R, Long E, Magne M, Mammei J, Margaziotis DJ, Markowitz P, Mazouz M, Meddi F, Meekins D, Michaels R, Mihovilovic M, Camacho CM, Nadel-Turonski P, Nuruzzaman N, Paremuzyan R, Puckett A, Punjabi V, Qiang Y, Rakhman A, Rashad MNH, Riordan S, Roche J, Russo G, Sabatié F, Saenboonruang K, Saha A, Sawatzky B, Selvy L, Shahinyan A, Sirca S, Solvignon P, Sperduto ML, Subedi R, Sulkosky V, Sutera C, Tobias WA, Urciuoli GM, Wang D, Wojtsekhowski B, Yao H, Ye Z, Zhan X, Zhang J, Zhao B, Zhao Z, Zheng X, and Zhu P

Abstract

The internal structure of nucleons (protons and neutrons) remains one of the greatest outstanding problems in modern nuclear physics. By scattering high-energy electrons off a proton we are able to resolve its fundamental constituents and probe their momenta and positions. Here we investigate the dynamics of quarks and gluons inside nucleons using deeply virtual Compton scattering (DVCS)-a highly virtual photon scatters off the proton, which subsequently radiates a photon. DVCS interferes with the Bethe-Heitler (BH) process, where the photon is emitted by the electron rather than the proton. We report herein the full determination of the BH-DVCS interference by exploiting the distinct energy dependences of the DVCS and BH amplitudes. In the regime where the scattering is expected to occur off a single quark, measurements show an intriguing sensitivity to gluons, the carriers of the strong interaction.

Published
2017
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7. Rosenbluth Separation of the π^{0} Electroproduction Cross Section Off the Neutron.

Author

Mazouz M, Ahmed Z, Albataineh H, Allada K, Aniol KA, Bellini V, Benali M, Boeglin W, Bertin P, Brossard M, Camsonne A, Canan M, Chandavar S, Chen C, Chen JP, Defurne M, de Jager CW, de Leo R, Desnault C, Deur A, El Fassi L, Ent R, Flay D, Friend M, Fuchey E, Frullani S, Garibaldi F, Gaskell D, Giusa A, Glamazdin O, Golge S, Gomez J, Hansen O, Higinbotham D, Holmstrom T, Horn T, Huang J, Huang M, Huber GM, Hyde CE, Iqbal S, Itard F, Kang H, Kang H, Kelleher A, Keppel C, Koirala S, Korover I, LeRose JJ, Lindgren R, Long E, Magne M, Mammei J, Margaziotis DJ, Markowitz P, Martí Jiménez-Argüello A, Meddi F, Meekins D, Michaels R, Mihovilovic M, Muangma N, Muñoz Camacho C, Nadel-Turonski P, Nuruzzaman N, Paremuzyan R, Puckett A, Punjabi V, Qiang Y, Rakhman A, Rashad MNH, Riordan S, Roche J, Russo G, Sabatié F, Saenboonruang K, Saha A, Sawatzky B, Selvy L, Shahinyan A, Sirca S, Solvignon P, Sperduto ML, Subedi R, Sulkosky V, Sutera C, Tobias WA, Urciuoli GM, Wang D, Wojtsekhowski B, Yao H, Ye Z, Zana L, Zhan X, Zhang J, Zhao B, Zhao Z, Zheng X, and Zhu P

Abstract

We report the first longitudinal-transverse separation of the deeply virtual exclusive π^{0} electroproduction cross section off the neutron and coherent deuteron. The corresponding four structure functions dσ_{L}/dt, dσ_{T}/dt, dσ_{LT}/dt, and dσ_{TT}/dt are extracted as a function of the momentum transfer to the recoil system at Q^{2}=1.75  GeV^{2} and x_{B}=0.36. The ed→edπ^{0} cross sections are found compatible with the small values expected from theoretical models. The en→enπ^{0} cross sections show a dominance from the response to transversely polarized photons, and are in good agreement with calculations based on the transversity generalized parton distributions of the nucleon. By combining these results with previous measurements of π^{0} electroproduction off the proton, we present a flavor decomposition of the u and d quark contributions to the cross section.

Published
2017
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8. Rosenbluth Separation of the π^{0} Electroproduction Cross Section.

Author

Defurne M, Mazouz M, Ahmed Z, Albataineh H, Allada K, Aniol KA, Bellini V, Benali M, Boeglin W, Bertin P, Brossard M, Camsonne A, Canan M, Chandavar S, Chen C, Chen JP, de Jager CW, de Leo R, Desnault C, Deur A, El Fassi L, Ent R, Flay D, Friend M, Fuchey E, Frullani S, Garibaldi F, Gaskell D, Giusa A, Glamazdin O, Golge S, Gomez J, Hansen O, Higinbotham D, Holmstrom T, Horn T, Huang J, Huang M, Huber GM, Hyde CE, Iqbal S, Itard F, Kang H, Kang H, Kelleher A, Keppel C, Koirala S, Korover I, LeRose JJ, Lindgren R, Long E, Magne M, Mammei J, Margaziotis DJ, Markowitz P, Martí Jiménez-Argüello A, Meddi F, Meekins D, Michaels R, Mihovilovic M, Muangma N, Muñoz Camacho C, Nadel-Turonski P, Nuruzzaman N, Paremuzyan R, Puckett A, Punjabi V, Qiang Y, Rakhman A, Rashad MN, Riordan S, Roche J, Russo G, Sabatié F, Saenboonruang K, Saha A, Sawatzky B, Selvy L, Shahinyan A, Sirca S, Solvignon P, Sperduto ML, Subedi R, Sulkosky V, Sutera C, Tobias WA, Urciuoli GM, Wang D, Wojtsekhowski B, Yao H, Ye Z, Zana L, Zhan X, Zhang J, Zhao B, Zhao Z, Zheng X, and Zhu P

Abstract

We present deeply virtual π^{0} electroproduction cross-section measurements at x_{B}=0.36 and three different Q^{2} values ranging from 1.5 to 2  GeV^{2}, obtained from Jefferson Lab Hall A experiment E07-007. The Rosenbluth technique is used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component and, thus, is far from the asymptotic limit predicted by perturbative quantum chromodynamics. Nonetheless, an indication of a nonzero longitudinal contribution is provided by the measured interference term σ_{LT}. Results are compared with several models based on the leading-twist approach of generalized parton distributions (GPDs). In particular, a fair agreement is obtained with models in which the scattering amplitude includes convolution terms of chiral-odd (transversity) GPDs of the nucleon with the twist-3 pion distribution amplitude. This experiment, together with previous extensive unseparated measurements, provides strong support to the exciting idea that transversity GPDs can be accessed via neutral pion electroproduction in the high-Q^{2} regime.

Published
2016
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9. Probing the repulsive core of the nucleon-nucleon interaction via the (4)He(e,e'pN) triple-coincidence reaction.

Author

Korover I, Muangma N, Hen O, Shneor R, Sulkosky V, Kelleher A, Gilad S, Higinbotham DW, Piasetzky E, Watson JW, Wood SA, Aguilera P, Ahmed Z, Albataineh H, Allada K, Anderson B, Anez D, Aniol K, Annand J, Armstrong W, Arrington J, Averett T, Badman T, Baghdasaryan H, Bai X, Beck A, Beck S, Bellini V, Benmokhtar F, Bertozzi W, Bittner J, Boeglin W, Camsonne A, Chen C, Chen JP, Chirapatpimol K, Cisbani E, Dalton MM, Daniel A, Day D, de Jager CW, De Leo R, Deconinck W, Defurne M, Flay D, Fomin N, Friend M, Frullani S, Fuchey E, Garibaldi F, Gaskell D, Gilman R, Glamazdin O, Gu C, Gueye P, Hamilton D, Hanretty C, Hansen JO, Hashemi Shabestari M, Holmstrom T, Huang M, Iqbal S, Jin G, Kalantarians N, Kang H, Khandaker M, LeRose J, Leckey J, Lindgren R, Long E, Mammei J, Margaziotis DJ, Markowitz P, Marti Jimenez-Arguello A, Meekins D, Meziani Z, Michaels R, Mihovilovic M, Monaghan P, Munoz Camacho C, Norum B, Nuruzzaman, Pan K, Phillips S, Pomerantz I, Posik M, Punjabi V, Qian X, Qiang Y, Qiu X, Rakhman A, Reimer PE, Riordan S, Ron G, Rondon-Aramayo O, Saha A, Schulte E, Selvy L, Shahinyan A, Sirca S, Sjoegren J, Slifer K, Solvignon P, Sparveris N, Subedi R, Tireman W, Wang D, Weinstein LB, Wojtsekhowski B, Yan W, Yaron I, Ye Z, Zhan X, Zhang J, Zhang Y, Zhao B, Zhao Z, Zheng X, Zhu P, and Zielinski R

Abstract

We studied simultaneously the (4)He(e,e'p), (4)He(e,e'pp), and (4)He(e,e'pn) reactions at Q(2)=2(GeV/c)(2) and x(B)>1, for an (e,e'p) missing-momentum range of 400 to 830  MeV/c. The knocked-out proton was detected in coincidence with a proton or neutron recoiling almost back to back to the missing momentum, leaving the residual A=2 system at low excitation energy. These data were used to identify two-nucleon short-range correlated pairs and to deduce their isospin structure as a function of missing momentum, in a region where the nucleon-nucleon (NN) force is expected to change from predominantly tensor to repulsive. The abundance of neutron-proton pairs is reduced as the nucleon momentum increases beyond ∼500  MeV/c. The extracted fraction of proton-proton pairs is small and almost independent of the missing momentum. Our data are compared with calculations of two-nucleon momentum distributions in (4)He and discussed in the context of probing the elusive repulsive component of the NN force.

Published
2014
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10. Search for a new gauge boson in electron-nucleus fixed-target scattering by the APEX experiment.

Author

Abrahamyan S, Ahmed Z, Allada K, Anez D, Averett T, Barbieri A, Bartlett K, Beacham J, Bono J, Boyce JR, Brindza P, Camsonne A, Cranmer K, Dalton MM, de Jager CW, Donaghy J, Essig R, Field C, Folts E, Gasparian A, Goeckner-Wald N, Gomez J, Graham M, Hansen JO, Higinbotham DW, Holmstrom T, Huang J, Iqbal S, Jaros J, Jensen E, Kelleher A, Khandaker M, LeRose JJ, Lindgren R, Liyanage N, Long E, Mammei J, Markowitz P, Maruyama T, Maxwell V, Mayilyan S, McDonald J, Michaels R, Moffeit K, Nelyubin V, Odian A, Oriunno M, Partridge R, Paolone M, Piasetzky E, Pomerantz I, Qiang Y, Riordan S, Roblin Y, Sawatzky B, Schuster P, Segal J, Selvy L, Shahinyan A, Subedi R, Sulkosky V, Stepanyan S, Toro N, Walz D, Wojtsekhowski B, and Zhang J

Abstract

We present a search at the Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling α' to electrons. Such a particle A' can be produced in electron-nucleus fixed-target scattering and then decay to an e + e- pair, producing a narrow resonance in the QED trident spectrum. Using APEX test run data, we searched in the mass range 175-250 MeV, found no evidence for an A'→ e+ e- reaction, and set an upper limit of α'/α ~/= 10(-6). Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and couplings for sub-GeV forces.

Published
2011
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