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Beam normal spin asymmetry in the quasireal Compton scattering approximation

Gorchtein, M. (2006) Beam normal spin asymmetry in the quasireal Compton scattering approximation. Physical Review C, 73 (5). Art. No. 055201. ISSN 0556-2813.

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he two-photon exchange contribution to the single spin asymmetries with the spin orientation normal to the reaction plane is discussed for elastic electron-proton scattering in the equivalent photon approximation. In this case, the hadronic part of the two-photon exchange amplitude describes real Compton scattering (RCS). We show that in the case of the beam normal spin asymmetry this approximation selects only the photon helicity flip amplitudes of RCS. At low energies, we make use of unitarity and estimate the contribution of the piN multipoles to the photon helicity flip amplitudes. In the Regge regime, the quasi-RCS (QRCS) approximation allows for a contribution from two-pion exchange, and we provide an estimate of such contributions.

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Additional Information:©2006 The American Physical Society (Received 10 May 2005; revised 21 March 2006; published 1 May 2006) 1In the literature, also, the An notation for beam normal spin asymmetry or vector analyzing power was adopted. The author is grateful to Professor M. M. Giannini for continuous support and to Dr. M. J. Ramsey-Musolf and D. O’Connell for numerous discussions and for thorough reading of the manuscript. The work was supported by Italian MIUR and INFN, and by U.S. Department of Energy contract DE-FG02-05ER41361.
Subject Keywords:elementary particle spin; exchange models; Compton effect; electron-proton scattering; helicity (elementary particles); Reggeon field theory
Issue or Number:5
Record Number:CaltechAUTHORS:GORprc06b
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3694
Deposited By: Archive Administrator
Deposited On:27 Jun 2006
Last Modified:02 Oct 2019 23:05

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