Compton scattering on the proton, neutron, and deuteron in chiral perturbation theory to

✍ Scribed by S.R. Beane; M. Malheiro; J.A. McGovern; D.R. Phillips; U. van Kolck

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 917 KB
• Volume: 747
• Category: Article
• ISSN: 0375-9474
• DOI: 10.1016/j.nuclphysa.2004.09.068

✦ Synopsis

We study Compton scattering in systems with A = 1 and 2 using chiral perturbation theory up to fourth order. For the proton we fit the two undetermined parameters in the O(Q 4 ) γp amplitude of McGovern to experimental data in the region ω, √ |t| 180 MeV, obtaining a χ 2 /d.o.f. of 133/113. This yields a model-independent extraction of proton polarizabilities based solely on low-energy data: α p = (12.1 ± 1.1(stat.)) +0.5 -0.5 (theory) and β p = (3.4 ± 1.1(stat.)) +0.1 -0.1 (theory), both in units of 10 -4 fm 3 . We also compute Compton scattering on deuterium to O(Q 4 ). The γ d amplitude is a sum of one-and two-nucleon mechanisms, and contains two undetermined parameters, which are related to the isoscalar nucleon polarizabilities. We fit data points from three recent γ d scattering experiments with a χ 2 /d.o.f. = 26.6/20, and find α N = (13.0 ± 1.9 (stat.)) +3.9 -1.5 (theory) and a β N that is consistent with zero within sizable error bars.