Polarization transfer observables in elastic electron-proton scattering at Q2=2.5, 5.2, 6.8, and 8.5 GeV2

被引：81

作者：

Puckett, A. J. R. ^{[1
]}

Brash, E. J. ^{[2
,3
]}

Jones, M. K. ^{[3
]}

Luo, W. ^{[4
]}

Meziane, M. ^{[5
]}

Pentchev, L. ^{[3
]}

Perdrisat, C. F. ^{[5
]}

Punjabi, V. ^{[6
]}

Wesselmann, F. R. ^{[6
]}

Afanasev, A. ^{[7
]}

Ahmidouch, A. ^{[8
]}

Albayrak, I. ^{[9
]}

Aniol, K. A. ^{[10
]}

Arrington, J. ^{[11
]}

Asaturyan, A. ^{[12
]}

Baghdasaryan, H. ^{[13
]}

Benmokhtar, F. ^{[14
]}

Bertozzi, W. ^{[15
]}

Bimbot, L. ^{[16
,17
]}

Bosted, P. ^{[3
]}

Boeglin, W. ^{[18
]}

Butuceanu, C. ^{[19
]}

Carter, P. ^{[2
]}

Chernenko, S. ^{[20
]}

Christy, M. E. ^{[9
]}

Commisso, M. ^{[13
]}

Cornejo, J. C. ^{[10
]}

Covrig, S. ^{[3
]}

Danagoulian, S. ^{[8
]}

Daniel, A. ^{[21
]}

Davidenko, A. ^{[22
]}

Day, D. ^{[13
]}

Dhamija, S. ^{[18
]}

Dutta, D. ^{[23
]}

Ent, R. ^{[3
]}

Frullani, S. ^{[24
,25
]}

Fenker, H. ^{[3
]}

Frlez, E. ^{[13
]}

Garibaldi, F. ^{[24
,25
]}

Gaskell, D. ^{[3
]}

Gilad, S. ^{[15
]}

Gilman, R. ^{[3
,26
]}

Goncharenko, Y. ^{[22
]}

Hafidi, K. ^{[11
]}

Hamilton, D. ^{[27
]}

Higinbotham, D. W. ^{[3
]}

Hinton, W. ^{[6
]}

Horn, T. ^{[3
]}

Hu, B. ^{[4
]}

Huang, J. ^{[15
]}

机构：

[1] Univ Connecticut, Storrs, CT 06269 USA

[2] Christopher Newport Univ, Newport News, VA 23606 USA

[3] Thomas Jefferson Natl Accelerator Facil, Newport News, VA 23606 USA

[4] Lanzhou Univ, Lanzhou 730000, Gansu, Peoples R China

[5] Coll William & Mary, Williamsburg, VA 23187 USA

[6] Norfolk State Univ, Norfolk, VA 23504 USA

[7] George Washington Univ, Washington, DC 20523 USA

[8] North Carolina A&T State Univ, Greensboro, NC 27411 USA

[9] Hampton Univ, Hampton, VA 23668 USA

[10] Calif State Univ Los Angeles, Los Angeles, CA 90032 USA

[11] Argonne Natl Lab, Argonne, IL 60439 USA

[12] Yerevan Phys Inst, Yerevan 375036, Armenia

[13] Univ Virginia, Charlottesville, VA 22904 USA

[14] Duquesne Univ, Pittsburgh, PA 15282 USA

[15] MIT, 77 Massachusetts Ave, Cambridge, MA 02139 USA

[16] CNRS, Inst Phys Nucl, IN2P3, Paris, France

[17] Univ Paris 11, Paris, France

[18] Florida Int Univ, Miami, FL 33199 USA

[19] Univ Regina, Regina, SK S4S 0A2, Canada

[20] JINR LHE, Dubna 141980, Moscow Region, Russia

[21] Ohio Univ, Athens, OH 45701 USA

[22] IHEP, Protvino 142284, Moscow Region, Russia

[23] Mississippi State Univ, Mississippi, MS 39762 USA

[24] INFN, Sez Sanita, I-00161 Rome, Italy

[25] Inst Super Sanita, I-00161 Rome, Italy

[26] Rutgers State Univ, Piscataway, NJ 08855 USA

[27] Univ Glasgow, Glasgow G12 8QQ, Lanark, Scotland

[28] Univ Witwatersrand, Johannesburg, South Africa

[29] Univ Maryland, College Pk, MD 20742 USA

[30] SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA

[31] Univ Chem Technol & Met, Sofia, Bulgaria

[32] Tel Aviv Univ, Tel Aviv, Israel

[33] Univ Ljubljana, Fac Math & Phys, SI-1000 Ljubljana, Slovenia

[34] Jozef Stefan Inst, SI-1000 Ljubljana, Slovenia

[35] SPhN, DSM, IRFU, F-91191 Gif Sur Yvette, France

来源：

PHYSICAL REVIEW C | 2017年 / 96卷 / 05期

基金：

美国国家科学基金会; 加拿大自然科学与工程研究理事会;

关键词：

ELECTROMAGNETIC FORM-FACTORS; SQUARED 4-MOMENTUM TRANSFERS; CONSTITUENT-QUARK-MODEL; PERTURBATIVE QCD; SCALING LAWS; NUCLEON; RATIO; 2-PHOTON-EXCHANGE; DYNAMICS; BARYONS;

D O I：

10.1103/PhysRevC.96.055203

中图分类号：

O57 [原子核物理学、高能物理学];

学科分类号：

070202 ;

摘要：

Background: Interest in the behavior of nucleon electromagnetic form factors at large momentum transfers has steadily increased since the discovery, using polarization observables, of the rapid decrease of the ratio G(E)(p)/G(M)(p) of the proton's electric and magnetic form factors for momentum transfers Q(2) greater than or similar to 1 GeV2, in strong disagreement with previous extractions of this ratio using the traditional Rosenbluth separation technique. Purpose: The GEp-III and GEp-2 gamma experiments were carried out in Jefferson Laboratory's ( JLab's) Hall C from 2007 to 2008, to extend the knowledge of G(E)(p) /G(M)(p) to the highest practically achievable Q(2) given the maximum beam energy of 6 GeV and to search for effects beyond the Born approximation in polarization transfer observables of elastic (e) over right arrowp scattering. This article provides an expanded description of the common experimental apparatus and data analysis procedures, and reports the results of a final reanalysis of the data from both experiments, including the previously unpublished results of the full-acceptance dataset of the GEp-2 gamma experiment. Methods: Polarization transfer observables in elastic (e) over right arrowp -> e (p) over right arrow scattering were measured at central Q(2) values of 2.5, 5.2, 6.8, and 8.54 GeV2. At Q 2 = 2.5 GeV2, data were obtained for central values of the virtual photon polarization parameter is an element of of 0.149, 0.632, and 0.783. 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. Results: 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 is an element of = 0.632 and 0.783 relative to the original publication. Conclusions: The final GEp-III results show that the decrease with Q(2) of G(E)(p)/G(M)(p) continues to Q(2) = 8.5 GeV2, but at a slowing rate relative to the approximately linear decrease observed in earlier Hall A measurements. At Q(2) = 8.5 GeV2, G(E)(p)/G(M)(p) remains positive but is consistent with zero. At Q(2) = 2.5 GeV2, G(E)(p)/G(M)(p) derived from the polarization component ratio R alpha P-t/P-l shows no statistically significant is an element of dependence, as expected in the Born approximation. On the other hand, the ratio P-l/P-l(Born) of the longitudinal polarization transfer component to its Born value shows an enhancement of roughly 1.7% at is an element of = 0.783 relative to is an element of = 0.149, with approximate to 2.2 sigma significance based on the total uncertainty, implying a similar effect in the transverse component Pt that cancels in the ratio R.

引用

页数：40

共 180 条

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