Measurement of two-photon exchange effect by comparing elastic e±p cross sections
Measurement of two-photon exchange effect by comparing elastic e±p cross sections
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DOI：
10.1103/physrevc.95.065201
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发表时间：
2016-03
影响因子：
3.1
通讯作者：
D. Rimal;D. Adikaram;B. Raue;L. Weinstein;J. Arrington;W. Brooks;M. Ungaro;K. Adhikari;Z. Akbar;S. Pereira;R. Badui;J. Ball;N. Baltzell;M. Battaglieri;V. Batourine;I. Bedlinskiy;R. Bennett;A. Biselli;S. Boiarinov;W. Briscoe;S. Bultmann;D. Carman;A. Celentano;T. Chetry;G. Ciullo;L. Clark;L. Colaneri;P. Cole;N. Compton;M. Contalbrigo;O. Cortes;V. Crede;A. D’Angelo;N. Dashyan;R. Vita;A. Deur;C. Djalali;R. Dupré;H. Egiyan;A. Alaoui;Lamiaa El Fassi;P. Eugenio;G. Fedotov;R. Fersch;A. Filippi;J. Fleming;T. Forest;A. Fradi;N. Gevorgyan;Y. Ghandilyan;G. Gilfoyle;K. Giovanetti;F. Girod;C. Gleason;W. Gohn;E. Golovatch;R. Gothe;K. Griffioen;L. Guo;K. Hafidi;C. Hanretty;N. Harrison;M. Hattawy;D. Heddle;K. Hicks;M. Holtrop;S. Hughes;Y. Ilieva;D. Ireland;B. Ishkhanov;E. Isupov;D. Jenkins;H. Jiang;S. Joosten;D. Keller;P. Khetarpal;G. Khachatryan;M. Khandaker;W. Kim;A. Klein;F. Klein;V. Kubarovsky;S. Kuhn;S. Kuleshov;L. Lanza;P. Lenisa;K. Livingston;H. Lu;I. Macgregor;N. Markov;B. Mckinnon;M. Mestayer;M. Mirazita;V. Mokeev;A. Movsisyan;E. Munevar;C. Camacho;P. Nadel-Turonski;A. Ni;S. Niccolai;G. Niculescu;I. Niculescu;M. Osipenko;A. Ostrovidov;M. Paolone;R. Paremuzyan;K. Park;E. Pasyuk;W. Phelps;S. Pisano;O. Pogorelko;J. Price;Y. Prok;D. Protopopescu;A. Puckett;Alessandro Rizzo;G. Rosner;P. Rossi;P. Roy;F. Sabati'e;C. Salgado;R. Schumacher;E. Seder;Y. Sharabian;I. Skorodumina;G. Smith;D. Sokhan;N. Sparveris;I. Stanković;S. Stepanyan;S. Strauch;V. Sytnik;M. Taiuti;B. Torayev;H. Voskanyan;E. Voutier;N. Walford;D. Watts;X. Wei;M. Wood;N. Zachariou;L. Zana;J. Zhang;Z. Zhao;I. Zonta
中科院分区：
文献类型：
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作者：
D. Rimal;D. Adikaram;B. Raue;L. Weinstein;J. Arrington;W. Brooks;M. Ungaro;K. Adhikari;Z. Akbar;S. Pereira;R. Badui;J. Ball;N. Baltzell;M. Battaglieri;V. Batourine;I. Bedlinskiy;R. Bennett;A. Biselli;S. Boiarinov;W. Briscoe;S. Bultmann;D. Carman;A. Celentano;T. Chetry;G. Ciullo;L. Clark;L. Colaneri;P. Cole;N. Compton;M. Contalbrigo;O. Cortes;V. Crede;A. D’Angelo;N. Dashyan;R. Vita;A. Deur;C. Djalali;R. Dupré;H. Egiyan;A. Alaoui;Lamiaa El Fassi;P. Eugenio;G. Fedotov;R. Fersch;A. Filippi;J. Fleming;T. Forest;A. Fradi;N. Gevorgyan;Y. Ghandilyan;G. Gilfoyle;K. Giovanetti;F. Girod;C. Gleason;W. Gohn;E. Golovatch;R. Gothe;K. Griffioen;L. Guo;K. Hafidi;C. Hanretty;N. Harrison;M. Hattawy;D. Heddle;K. Hicks;M. Holtrop;S. Hughes;Y. Ilieva;D. Ireland;B. Ishkhanov;E. Isupov;D. Jenkins;H. Jiang;S. Joosten;D. Keller;P. Khetarpal;G. Khachatryan;M. Khandaker;W. Kim;A. Klein;F. Klein;V. Kubarovsky;S. Kuhn;S. Kuleshov;L. Lanza;P. Lenisa;K. Livingston;H. Lu;I. Macgregor;N. Markov;B. Mckinnon;M. Mestayer;M. Mirazita;V. Mokeev;A. Movsisyan;E. Munevar;C. Camacho;P. Nadel-Turonski;A. Ni;S. Niccolai;G. Niculescu;I. Niculescu;M. Osipenko;A. Ostrovidov;M. Paolone;R. Paremuzyan;K. Park;E. Pasyuk;W. Phelps;S. Pisano;O. Pogorelko;J. Price;Y. Prok;D. Protopopescu;A. Puckett;Alessandro Rizzo;G. Rosner;P. Rossi;P. Roy;F. Sabati'e;C. Salgado;R. Schumacher;E. Seder;Y. Sharabian;I. Skorodumina;G. Smith;D. Sokhan;N. Sparveris;I. Stanković;S. Stepanyan;S. Strauch;V. Sytnik;M. Taiuti;B. Torayev;H. Voskanyan;E. Voutier;N. Walford;D. Watts;X. Wei;M. Wood;N. Zachariou;L. Zana;J. Zhang;Z. Zhao;I. Zonta
[背景]通过非极化和极化电子散射实验测量的质子的电磁形状因子显示出显著的不一致，随着四阶动量转移的平方（$Q^{2}$）而增长。计算表明，通过考虑双光子交换（TPE）的贡献，这两种测量可以在很大程度上得到调和。TPE效应通常不包括在辐射校正的标准集合中，因为TPE效应的理论计算高度依赖于模型，并且直到最近，还没有观察到显着TPE效应的直接证据。【目的】测量正电子-质子和电子-质子弹性散射截面的比值，以确定TPE对电子-质子弹性散射的贡献，从而解决质子电形状因子的差异。[方法]在Jefferson实验室的Hall B中，将5.6 GeV的初级电子束通过辐射器产生韧致辐射光子束，然后将光子束通过反射器产生电子/正电子对，从而产生混合的同时电子-正电子束。然后，有用能量约为0.85至3.5 GeV的混合电子-正电子（轻子）束撞击位于CEBAF大型接受谱仪（CLAS）内的30厘米长的液氢（LH 2 $）靶。通过对散射轻子和反冲质子的探测，我们识别并重建了弹性散射事件，并确定了入射轻子的能量。实验的详细描述。
[Background] The electromagnetic form factors of the proton measured by unpolarized and polarized electron scattering experiments show a significant disagreement that grows with the squared four momentum transfer ($Q^{2}$). Calculations have shown that the two measurements can be largely reconciled by accounting for the contributions of two-photon exchange (TPE). TPE effects are not typically included in the standard set of radiative corrections since theoretical calculations of the TPE effects are highly model dependent, and, until recently, no direct evidence of significant TPE effects has been observed. [Purpose] We measured the ratio of positron-proton to electron-proton elastic-scattering cross sections in order to determine the TPE contribution to elastic electron-proton scattering and thereby resolve the proton electric form factor discrepancy. [Methods] We produced a mixed simultaneous electron-positron beam in Jefferson Lab's Hall B by passing the 5.6 GeV primary electron beam through a radiator to produce a bremsstrahlung photon beam and then passing the photon beam through a convertor to produce electron/positron pairs. The mixed electron-positron (lepton) beam with useful energies from approximately 0.85 to 3.5 GeV then struck a 30-cm long liquid hydrogen (LH$_2$) target located within the CEBAF Large Acceptance Spectrometer (CLAS). By detecting both the scattered leptons and the recoiling protons we identified and reconstructed elastic scattering events and determined the incident lepton energy. A detailed description of the experiment is presented.