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The Compton scattering cross section on the proton has been measured at laboratory angles of 90$^\circ$ and 135$^\circ$ using tagged photons in the energy range 70--100 MeV and simultaneously using untagged photons in the range…

Nuclear Experiment · Physics 2008-11-26 B. E. MacGibbon , G. Garino , M. A. Lucas , A. M. Nathan , G. Feldman , B. Dolbilkin

We calculate two-photon exchange (TPE) amplitudes for the elastic electron-proton scattering, and take into account intermediate hadronic states containing \pi N system with total angular momentum 1/2 or 3/2, which includes 8 different…

High Energy Physics - Phenomenology · Physics 2015-09-16 Dmitry Borisyuk , Alexander Kobushkin

The ratio of the electric and magnetic form factor of the proton, $\mu_p G_E^p/G_M^p$, has been measured for elastic electron-proton scattering with polarized beam and target up to four-momentum transfer squared, $Q^2=5.66$ (GeV/c)$^2$…

We report the first precision measurement of the proton electric to magnetic form factor ratio from spin-dependent elastic scattering of longitudinally polarized electrons from a polarized hydrogen internal gas target. The measurement was…

The details of the calculation of the two-boson exchange effects in the parity-violating elastic $ep$ scattering within a simple hadronic model, including both the nucleon and $\Delta(1232)$-resonance intermediate states, are presented. We…

Nuclear Theory · Physics 2010-04-14 Hai Qing Zhou , Chung Wen Kao , Shin Nan Yang , Keitaro Nagata

The Qweak experiment which ran at Jefferson Lab in Newport News, VA, measured the weak charge of the proton $Q_W^p$ via elastic electron-proton scattering. Longitudinally polarized electrons were scattered from an unpolarized liquid…

Nuclear Experiment · Physics 2016-01-28 Donald Jones

Polarization of both electron and positron beams at a future linear collider (LC) allows for the measurement of transverse polarization asymmetries. These asymmetries have been shown to be particularly sensitive to graviton or other spin-2,…

High Energy Physics - Phenomenology · Physics 2009-11-10 Thomas G. Rizzo

Elastic lepton scattering off of a nucleon has proved to be an efficient tool to study the structure of the hadron. Modern cross section and asymmetry measurements at Jefferson Lab require effects beyond the leading order Born approximation…

High Energy Physics - Phenomenology · Physics 2018-07-18 Oleksandr Koshchii , Andrei Afanasev

A reanalysis of unpolarized electron-proton elastic scattering data is done in terms of the electric to magnetic form factor squared ratio. This observable is in principle more robust against experimental correlations and global…

Nuclear Theory · Physics 2016-12-07 Simone Pacetti , Egle Tomasi Gustafsson

Polarization transfer in quasi-elastic nucleon knockout is sensitive to the properties of the nucleon in the nuclear medium, including possible modification of the nucleon form factor and/or spinor. In our recently completed experiment…

Nuclear Experiment · Physics 2019-08-13 S. Malace , M. Paolone , S. Strauch

The $e^{+}p$ and $e^{-}p$ scattering data recorded at HERA during the recent years offer the possibility to study electroweak effects in $ep$ interactions apparent at high momentum transfers, $Q^{2}$, and to reveal information on the proton…

High Energy Physics - Experiment · Physics 2007-05-23 Hans-Christian Schultz-Coulon

The polarization of the secondary protons in the (p,2p) reaction with the S - shell protons of nuclei 4He, 6Li, 12C, 28Si, 40Ca was measured at 1 GeV unpolarized proton beam. The spin correlation parameters Cij for the 4He and 12C targets…

Systematic differences in the the proton's charge radius, as determined by ordinary atoms and muonic atoms, have caused a resurgence of interest in elastic lepton scattering measurements. The proton's charge radius, defined as the slope of…

The general form of the cross section as well as the polarizations of electron-deuteron elastic scattering are given. Two-photon exchange effects are analyzed. Possible signatures of the two-photon exchange effects in the electron-deuteron…

Nuclear Theory · Physics 2008-11-26 Yu Bing Dong , Chung Wen Kao , Shin Nan Yang , Yu Chun Chen

We investigate the effect of high order radiative corrections in unpolarized electron proton elastic scattering and compare with the calculations at lowest order, which are usually applied to experimental data. We show that higher order…

High Energy Physics - Phenomenology · Physics 2008-05-26 E. A. Kuraev , Yu. Bystritskiy , S. Bakmaev , V. V. Bytev , E. Tomasi-Gustafsson

We evaluate the two-photon exchange correction to the unpolarized cross section in the elastic muon-proton scattering within dispersion relations. One of the six independent invariant amplitudes requires a subtraction. We fix the…

High Energy Physics - Phenomenology · Physics 2024-10-28 Oleksandr Tomalak , Marc Vanderhaeghen

The Jefferson Lab Q_weak experiment determined the weak charge of the proton by measuring the parity-violating elastic scattering asymmetry of longitudinally polarized electrons from an unpolarized liquid hydrogen target at small momentum…

Instrumentation and Detectors · Physics 2015-01-08 Qweak Collaboration , T. Allison , M. Anderson , D. Androic , D. S. Armstrong , A. Asaturyan , T. D. Averett , R. Averill , J. Balewski , J. Beaufait , R. S. Beminiwattha , J. Benesch , F. Benmokhtar , J. Bessuille , J. Birchall , E. Bonnell , J. Bowman , P. Brindza , D. B. Brown , R. D. Carlini , G. D. Cates , B. Cavness , G. Clark , J. C. Cornejo , S. Covrig Dusa , M. M. Dalton , C. A. Davis , D. C. Dean , W. Deconinck , J. Diefenbach , K. Dow , J. F. Dowd , J. A. Dunne , D. Dutta , W. S. Duvall , J. R. Echols , M. Elaasar , W. R. Falk , K. D. Finelli , J. M. Finn , D. Gaskell , M. T. W. Gericke , J. Grames , V. M. Gray , K. Grimm , F. Guo , J. Hansknecht , D. J. Harrison , E. Henderson , J. R. Hoskins , E. Ihloff , K. Johnston , D. Jones , M. Jones , R. Jones , M. Kargiantoulakis , J. Kelsey , N. Khan , P. M. King , E. Korkmaz , S. Kowalski , A. Kubera , J. Leacock , J. P. Leckey , A. R. Lee , J. H. Lee , L. Lee , Y. Liang , S. MacEwan , D. Mack , J. A. Magee , R. Mahurin , J. Mammei , J. W. Martin , A. McCreary , M. H. McDonald , M. J. McHugh , P. Medeiros , D. Meekins , J. Mei , R. Michaels , A. Micherdzinska , A. Mkrtchyan , H. Mkrtchyan , N. Morgan , J. Musson , K. E. Mesick , A. Narayan , L. Z. Ndukum , V. Nelyubin , Nuruzzaman , W. T. H. van Oers , A. K. Opper , S. A. Page , J. Pan , K. D. Paschke , S. K. Phillips , M. L. Pitt , M. Poelker , J. F. Rajotte , W. D. Ramsay , W. R. Roberts , J. Roche , P. W. Rose , B. Sawatzky , T. Seva , M. H. Shabestari , R. Silwal , N. Simicevic , G. R. Smith , S. Sobczynski , P. Solvignon , D. T. Spayde , B. Stokes , D. W. Storey , A. Subedi , R. Subedi , R. Suleiman , V. Tadevosyan , W. A. Tobias , V. Tvaskis , E. Urban , B. Waidyawansa , P. Wang , S. P. Wells , S. A. Wood , S. Yang , S. Zhamkochyan , R. B. Zielinski

Double-polarization observables in the reaction $\vec{e}p \rightarrow e'\vec{p'}\gamma{}$ have been measured at $Q^2=0.33 (GeV/c)^2$. The experiment was performed at the spectrometer setup of the A1 Collaboration using the 855 MeV polarized…

In this work, the two-photon-exchange (TPE) effects in $e^+e^- \rightarrow \pi^+ \pi^-$ at small $\sqrt{s}$ are discussed within a hadronic model. In the limit $m_e\rightarrow 0$, the TPE contribution to the amplitude can be described by…

High Energy Physics - Phenomenology · Physics 2020-09-30 Zhong-Hua Zhao , Hui-Yun Cao , Hai-Qing Zhou