Two-photon exchange contribution to elastic electron-proton scattering: measurements at the VEPP-3 storage ring

被引:1
作者
Rachek, I. A. [1 ]
Arrington, J. [2 ]
Dmitriev, V. F. [1 ,3 ]
Gauzshtein, V. V. [4 ]
Gramolin, A. V. [1 ]
Holt, R. J. [2 ]
Kaminskiy, V. V. [1 ]
Lazarenko, B. A. [1 ]
Mishnev, S. I. [1 ]
Muchnoi, N. Yu [1 ,3 ]
Neufeld, V. V. [1 ]
Nikolenko, D. M. [1 ]
Sadykov, R. Sh [1 ]
Shestakov, Yu V. [1 ]
Stibunov, V. N.
Toporkov, D. K. [1 ,3 ]
de Vries, H. [5 ]
Zevakov, S. A. [1 ]
Zhilich, V. N. [1 ,3 ]
机构
[1] Budker Inst Nucl Phys SB RAS, Novosibirsk, Russia
[2] Argonne Natl Lab, Argonne, IL 60439 USA
[3] Novosibirsk State Univ, Novosibirsk 630090, Russia
[4] Tomsk Polytech Univ, Inst Nucl Phys, Tomsk, Russia
[5] NIKHEF, Amsterdam, Netherlands
关键词
two-photon exchange; proton form factors; elastic scattering; POSITRONS;
D O I
10.1088/0031-8949/2015/T166/014017
中图分类号
O4 [物理学];
学科分类号
0702 ;
摘要
A striking discrepancy between the results for the ratio of electric and magnetic form factors of the proton obtained by two approaches: the Rosenbluth extraction from the unpolarized cross section and the double-polarization measurements has led to a serious re-examination of the role played by two-photon exchange diagrams. The evaluation of such diagrams could not be done in model-independent way, which means an experimental verification is required. One of the direct ways to do this is to measure the ratio of positron-proton and electron-proton elastic scattering cross-sections for identical kinematics. Such a measurement has been performed at the VEPP-3 storage ring at Novosibirsk. There were two runs at beam energies of 1.6 and 1.0 GeV at several ranges of scattering angle. The measurements covered the transferred momentum Q(2) up to 1.5 GeV2 and the virtual photon polarization parameter is an element of down to 0.2. The VEPP-3 experimental approach is described and the results of the measurements are presented.
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页数:5
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