Physical Sciences and Mathematics Commons^™

Measurement Of Two-Photon Exchange Effect By Comparing Elastic E±P Cross Sections, P. Rimal, D. Adikaram, B. A. Raue, L. B. Weinstein, J. Arrington, W. K. Brooks, M. Ungaro, K. P. Adhikari, A. V. Afanasev, Z. Akbar, S. Anefalos Pereira, R. A. Badui, J. Ball, N. A. Baltzell, M. Battaglieri, V. Batourine, I. Bedlinskiy, A. S. Biselli, S. Boiarinov, W. J. Briscoe, S. Bültmann, V. D. Burkert, D. S. Carman, A. Celentano, T. Chetry, G. Ciullo, L. Clark, L. Colaneri, P. L. Cole, N. Compton, Wesley P. Gohn

Physics and Astronomy Faculty Publications

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 (Q²). 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 …

First Measurement Of Unpolarized Semi-Inclusive Deep-Inelastic Scattering Cross Sections From A 3He Target, X. Yan, K. Allada, K. Aniol, J. R. M. Annand, T. Averett, F. Benmokhtar, W. Bertozzi, P. C. Bradshaw, P. Bosted, A. Camsonne, M. Canan, G. D. Cates, C. Chen, J. -P. Chen, W. Chen, K. Chirapatpimol, E. Chudakov, E. Cisbani, J. C. Cornejo, F. Cusanno, M. M. Dalton, W. Deconinck, C. W. De Jager, R. De Leo, X. Deng, A. Deur, H. Ding, P. A. M. Dolph, C. Dutta, D. Dutta, A. Kolarkar, Wolfgang Korsch

Physics and Astronomy Faculty Publications

The unpolarized semi-inclusive deep-inelastic scattering (SIDIS) differential cross sections in ³He(e,e′π^±)X have been measured for the first time in Jefferson Lab experiment E06-010 with a 5.9 GeV e⁻ beam on a ³He gas target. The experiment focuses on the valence quark region, covering a kinematic range 0.12 < x_bj < 0.45, 1 < Q² < 4 (GeV/c)², 0.45 < z_h < 0.65, and 0.05 < P_t < 0.55 GeV/c. The extracted SIDIS differential cross sections of π^± production are compared with existing phenomenological models while the ³He nucleus approximated as two protons and one …

Target And Beam-Target Spin Asymmetries In Exclusive Pion Electroproduction For Q2 > 1 Gev2. Ii. Ep → Eπ0P, P. E. Bosted, A. Kim, K. P. Adhikari, D. Adikaram, Z. Akbar, M. J. Amaryan, S. Anefalos Pereira, H. Avakian, R. A. Badui, J. Ball, I. Balossino, M. Battaglieri, I. Bedlinskiy, A. S. Biselli, S. Boiarinov, W. J. Briscoe, W. K. Brooks, S. Bültmann, V. D. Burkert, T. Cao, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, T. Chetry, G. Ciullo, L. Clark, L. Colaneri, P. L. Cole, M. Contalbrigo, Wesley P. Gohn

Physics and Astronomy Faculty Publications

Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive π⁰ electroproduction reaction γ^∗p → pπ⁰, expanding an analysis of the γ^∗p → nπ⁺ reaction from the same experiment. The results were obtained from scattering of 6-GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The kinematic ranges covered are 1.1 < W < 3 GeV and 1 < Q² < 6 GeV². Results were obtained for about 5700 bins in W, Q², cos(θ^∗), and ϕ^∗. The beam-target asymmetries were found …

Target And Beam-Target Spin Asymmetries In Exclusive Π+ And Π− Electroproduction With 1.6- To 5.7-Gev Electrons, P. E. Bosted, A. S. Biselli, S. Careccia, G. Dodge, R. Fersch, N. Guler, S. E. Kuhn, J. Pierce, Y. Prok, X. Zheng, K. P. Adhikari, D. Adikaram, Z. Akbar, M. J. Amaryan, S. Anefalos Pereira, G. Asryan, H. Avakian, R. A. Badui, J. Ball, N. A. Baltzell, M. Battaglieri, V. Batourine, I. Bedlinskiy, S. Boiarinov, W. J. Briscoe, S. Bültmann, V. D. Burkert, T. Cao, D. S. Carman, A. Celentano, Wesley P. Gohn

Physics and Astronomy Faculty Publications

Beam-target double-spin asymmetries and target single-spin asymmetries in exclusive π+ and quasiexclusive π− electroproduction were obtained from scattering of 1.6- to 5.7-GeV longitudinally polarized electrons from longitudinally polarized protons (for π+) and deuterons (for π−) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. The kinematic range covered is 1.1 < W < 2.6 GeV and 0.05 < Q² < 5 GeV², with good angular coverage in the forward hemisphere. The asymmetry results were divided into approximately 40 000 kinematic bins for π+ from free protons and 15 000 bins for π− production from bound nucleons in the deuteron. The …