/ nucl-ex arXiv:1707.08587

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

Puckett, A.J.R. (UConn, Storrs) ; Brash, E.J. (Jefferson Lab) ; Jones, M.K. (Jefferson Lab) ; Luo, W. (Lanzhou U.) ; Meziane, M. (William-Mary Coll.) ; Pentchev, L. (Jefferson Lab) ; Perdrisat, C.F. (William-Mary Coll.) ; Punjabi, V. (Norfolk State U.) ; Wesselmann, F.R. (Norfolk State U.) ; Afanasev, A. (George Washington U.) ; Ahmidouch, A. (North Carolina A-T State U.) ; Albayrak, I. (COSM, Hampton) ; Aniol, K.A. (Cal State, L.A.) ; Arrington, J. (Argonne (main)) ; Asaturyan, A. (Yerevan Phys. Inst.) ; Baghdasaryan, H. (Virginia U.) ; Benmokhtar, F. (Duquesne U.) ; Bertozzi, W. (MIT) ; Bimbot, L. (Orsay, IPN) ; Bosted, P. (Jefferson Lab) ; Boeglin, W. (Florida Intl. U.) ; Butuceanu, C. (Regina U.) ; Carter, P. (Christopher Newport U.) ; Chernenko, S. (Dubna, JINR) ; Christy, E. (COSM, Hampton) ; Commisso, M. (Virginia U.) ; Cornejo, J.C. (Cal State, L.A.) ; Covrig, S. (Jefferson Lab) ; Danagoulian, S. (North Carolina A-T State U.) ; Daniel, A. (Ohio U., Athens) ; Davidenko, A. (Serpukhov, IHEP) ; Day, D. (Virginia U.) ; Dhamija, S. (Florida Intl. U.) ; Dutta, D. (Mississippi State U.) ; Ent, R. (Jefferson Lab) ; Frullani, S. (Rome, ISS) ; Fenker, H. (Jefferson Lab) ; Frlez, E. (Virginia U.) ; Garibaldi, F. (Rome, ISS) ; Gaskell, D. (Jefferson Lab) ; Gilad, S. (MIT) ; Gilman, R. (Jefferson Lab) ; Goncharenko, Y. (Serpukhov, IHEP) ; Hafidi, K. (Argonne (main)) ; Hamilton, D. (Glasgow U.) ; Higinbotham, D.W. (Jefferson Lab) ; Hinton, W. (Norfolk State U.) ; Horn, T. (Jefferson Lab) ; Hu, B. (Lanzhou U.) ; Huang, J. (MIT) ; Huber, G.M. (Regina U.) ; Jensen, E. (Christopher Newport U.) ; Keppel, C. (COSM, Hampton) ; Khandaker, M. (Norfolk State U.) ; King, P. (Ohio U., Athens) ; Kirillov, D. (Dubna, JINR) ; Kohl, M. (COSM, Hampton) ; Kravtsov, V. (Serpukhov, IHEP) ; Kumbartzki, G. (Rutgers U., Piscataway) ; Li, Y. (COSM, Hampton) ; Mamyan, V. (Virginia U.) ; Margaziotis, D.J. (Cal State, L.A.) ; Marsh, A. (Christopher Newport U.) ; Matulenko, Y. (Serpukhov, IHEP) ; Maxwell, J. (Virginia U.) ; Mbianda, G. (Witwatersrand U.) ; Meekins, D. (Jefferson Lab) ; Melnik, Y. (Serpukhov, IHEP) ; Miller, J. (Maryland U.) ; Mkrtchyan, A. (Yerevan Phys. Inst.) ; Mkrtchyan, H. (Yerevan Phys. Inst.) ; Moffit, B. (MIT) ; Moreno, O. (SLAC) ; Mulholland, J. (Virginia U.) ; Narayan, A. (Mississippi State U.) ; Nedev, S. (Chem. Tech. Metal. U., Sofia) ; Nuruzzaman (Mississippi State U.) ; Piasetzky, E. (Tel Aviv U.) ; Pierce, W. (Christopher Newport U.) ; Piskunov, N.M. (Dubna, JINR) ; Prok, Y. (Christopher Newport U.) ; Ransome, R.D. (Rutgers U., Piscataway) ; Razin, D.S. (Dubna, JINR) ; Reimer, P. (Argonne (main)) ; Reinhold, J. (Florida Intl. U.) ; Rondon, O. (Virginia U.) ; Shabestari, M. (Virginia U.) ; Shahinyan, A. (Yerevan Phys. Inst.) ; Shestermanov, K. (Serpukhov, IHEP) ; Širca, S. (Ljubljana U.) ; Sitnik, I. (Dubna, JINR) ; Smykov, L. (Dubna, JINR) ; Smith, G. (Jefferson Lab) ; Solovyev, L. (Serpukhov, IHEP) ; Solvignon, P. (Argonne (main)) ; Subedi, R. (Virginia U.) ; Tomasi-Gustafsson, E. (Orsay, IPN) ; Vasiliev, A. (Serpukhov, IHEP) ; Veilleux, M. (Christopher Newport U.) ; Wojtsekhowski, B.B. (Jefferson Lab) ; Wood, S. (Jefferson Lab) ; Ye, Z. (COSM, Hampton) ; Zanevsky, Y. (Dubna, JINR) ; Zhang, X. (Lanzhou U.) ; Zhang, Y. (Lanzhou U.) ; Zheng, X. (Virginia U.) ; Zhu, L. (MIT)

Pages: 43

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 1.7\% at $\epsilon = 0.783$ relative to $\epsilon = 0.149$, with $\approx 2.2\sigma$ significance based on the total uncertainty, implying a similar effect in the transverse component $P_t$ that cancels in the ratio $R$.

Web-Page: http://inspirehep.net/record/1613323/files/q2f2f1_Brodsky_GEP3PRC.png; http://inspirehep.net/record/1613323/files/GEp2g_summaryfig.png; http://inspirehep.net/record/1613323/files/gepgmp_allpol_roberts_GEP3PRC.png; http://inspirehep.net/record/1613323/files/BackgroundEstimationQ85.png; http://inspirehep.net/record/1613323/files/q2f2f1_belitsky_GEP3PRC.png; http://inspirehep.net/record/1613323/files/fig_phisumplusminusdiff_gep2gamma.png; http://inspirehep.net/record/1613323/files/Pinel_gep3.png; http://inspirehep.net/record/1613323/files/twogamma_top_GEP3PRC.png; http://inspirehep.net/record/1613323/files/gepgmp_vsVMD_GEP3PRC.png; http://inspirehep.net/record/1613323/files/gepgmp_allpol_chambers_GEP3PRC.png; http://inspirehep.net/record/1613323/files/gepgmp_world_027_GEP3PRC.png; http://inspirehep.net/record/1613323/files/gepgmp_allpol_allcs_GEP3PRC.png; http://inspirehep.net/record/1613323/files/gepgmp_vs_CQM_GEP3PRC.png; http://inspirehep.net/record/1613323/files/fig_axfpp_chi.png; http://inspirehep.net/record/1613323/files/Ay_vs_pT_Q2.png; http://inspirehep.net/record/1613323/files/FPPschematic_new.png; http://inspirehep.net/record/1613323/files/Aymax_Ayavg_vs_pinv.png; http://inspirehep.net/record/1613323/files/gepgd_GEP3PRC.png; http://inspirehep.net/record/1613323/files/Pinel_gep2gamma.png; http://inspirehep.net/record/1613323/files/gmpgd_spS_GEP3PRC.png; http://inspirehep.net/record/1613323/files/Rbcc_vs_epsilon_confidence_band.png; http://inspirehep.net/record/1613323/files/R_PT_PL_Q2_gep2g.png; http://inspirehep.net/record/1613323/files/fig_asym_gep3.png; http://inspirehep.net/record/1613323/files/bigcal_photo.png; http://inspirehep.net/record/1613323/files/ExclusivityCutsGEP3.png; http://inspirehep.net/record/1613323/files/fig_asym_gep2gamma.png; http://inspirehep.net/record/1613323/files/bg_vs_dpp_q85.png; http://inspirehep.net/record/1613323/files/GEp3summaryfig.png; http://inspirehep.net/record/1613323/files/arXiv:1707.08587.pdf

Note: 43 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. To be submitted to Phys. Rev. C. Abstract abbreviated to conform to arxiv length limits. Paper has PRC "structured abstract" format

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