Polarization phenomena in small-angle photoproduction of e{sup +}e{sup {minus}} pairs and the Gerasimov-Drell-Hearn sum rule
- P.N. Lebedev Physical Institute, Moscow, 117924 (Russia)
- Department of Physics, University of Perugia, I-06100 Perugia (Italy)
- Institut fuer Kernphysik, Universitaet Mainz, D-55099 Mainz (Germany)
Photoproduction of e{sup +}e{sup {minus}} pairs at small angles is investigated as a tool to determine the functions f{sub 1} and f{sub 2} entering the real-photon forward Compton scattering amplitude. The method is based on an interference of the Bethe-Heitler and the virtual Compton scattering mechanisms, generating an azimuthal asymmetry in the e{sup +} versus e{sup {minus}} yield. The general case of a circularly polarized beam and a longitudinally polarized target allows one to determine both the real and imaginary parts of f{sub 1} as well as f{sub 2}. The imaginary part of f{sub 2} requires target polarization only. We calculate cross sections and asymmetries of the reaction p({gamma},e{sup +}e{sup {minus}})p, estimate corrections and backgrounds, and propose suitable kinematical regions to perform the experiment. Our investigation shows that photoproduction of e{sup +}e{sup {minus}}-pairs off the proton and light nuclei may serve as a rather sensitive test of the validity of the Gerasimov-Drell-Hearn sum rule. {copyright} {ital 1998} {ital The American Physical Society}
- OSTI ID:
- 566012
- Journal Information:
- Physical Review, C, Vol. 57, Issue 1; Other Information: PBD: Jan 1998
- Country of Publication:
- United States
- Language:
- English
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