FIZIKA B 13 (2004)  1, 209-216

VIRTUAL COMPTON SCATTERING AT LOW ENERGY AND THE GENERALIZED POLARIZABILITIES OF THE NUCLEON

H. FONVIEILLE for the Jefferson Lab Hall A Collaboration and the VCS Collaboration

Laboratoire de Physique Corpusculaire IN2P3/CNRS,
Université Blaise Pascal - Clermont II, 63170 AUBIERE Cedex, FRANCE

Received 12 September 2003;     Accepted 26 April 2004
Online 10 October 2004

Virtual Compton scattering (VCS) g^* p ® gp at low CM energy gives access to the generalized polarizabilities of the nucleon. These observables generalize the concept of electromagnetic polarizabilities to the case of a virtual photon. Dedicated VCS experiments have been performed at MAMI, Jefferson Lab and MIT-Bates. The experimental status is reviewed, including methods of analysis and physical results. The measurement of absolute (ep ® ep g) cross sections allows the extraction of the two unpolarized VCS structure functions  P_LL-P_TT/e  and P_LT, which are combinations of the generalized polarizabilities of the proton. Future prospects in the field of VCS at low energy are also presented.

PACS numbers: 13.60.Fz
UDC 539.12

Keywords: virtual Compton scattering, cross sections, nucleon generalized polarizabilities

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