Test of low-energy theorems for 1H(--> gamma, pi(0))(H)in the threshold hegion.
/ Authors
A. Schmidt, P. Achenbach, J. Ahrens, H. Arends, R. Beck, A. Bernstein, V. Hejny, M. Kotulla, B. Krusche, V. Kuhr
and 11 more authors
R. Leukel, I. MacGregor, J. Mcgeorge, V. Metag, V. O. D. León, F. Rambo, U. Siodlaczek, H. Ströher, J. Weiss, F. Wissmann, M. Wolf
/ Abstract
The photon asymmetry in the reaction H-1(, pi (0))H-1 close to threshold has been measured for the first time with the photon spectrometer TAPS using linearly polarized photons from the tagged-photon facility at the Mainz Microtron MAMI. The total and differential cross sections were also measured simultaneously with the photon asymmetry. This allowed determination of the S-wave and all three P-wave amplitudes. The values obtained at threshold are E0+ = [-1.33 +/- 0.08(stat) +/- 0.03(syst)] x 10(-3)/m(pi+), P-1 = [9.47 +/- 0.08(stat) +/- 0.29(syst)] x 10(-3)q /m(pi+)(2) P-2 [-9.46 +/- 0.1(stat) +/- 0.29(syst)] x 10(-3)q/m(pi+)(2), and P-3 = [11.48 +/- 0.06(stat) +/- 0.35(syst)] x 10(-3)q/m(pi+)(2).
Journal: Physical Review Letters