Compton scattering from the free and bound proton at backward angles abovepi-threshold

Citation
F. Wissmann et al., Compton scattering from the free and bound proton at backward angles abovepi-threshold, NUCL PHYS A, 660(2), 1999, pp. 232-245
Citations number
36
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
NUCLEAR PHYSICS A
ISSN journal
0375-9474 → ACNP
Volume
660
Issue
2
Year of publication
1999
Pages
232 - 245
Database
ISI
SICI code
0375-9474(19991122)660:2<232:CSFTFA>2.0.ZU;2-Q
Abstract
Differential cross sections for Compton scattering from the free proton at Theta(gamma)(lab) = 130.7 degrees in the energy region from 200 MeV to 410 MeV and far quasi-free Compton scattering from the proton bound in the deut eron at Theta(gamma)(lab) = 148.8 degrees in the energy region from 200 MeV to 290 MeV have been measured. The free proton data are in agreement with dispersion-theory predictions based on standard parameters. The difference of the proton polarizabilities has been extracted from the quasi-free data. Our result, <(alpha)over bar> - <(beta)over bar> = [9.1 +/- 1.7(stat + sys t) +/- 1.2(mod)] x 10(-4) fm(3), is in reasonable agreement with the world average of the free proton data if the backward spin polarizability gamma(p i) is taken to be -37.6 x 10(-4) fm(4) as predicted by dispersion theory in agreement with many theoretical calculations. This implies that quasi-free Compton scattering may also be used to determine the electromagnetic polar izabilities of the neutron. No indication has been found of a recently sugg ested new contribution to gamma(pi). (C) 1999 Elsevier Science B.V. All rig hts reserved.