Precise Measurement of Differential Cross Sections of the Sigma(- )p -> Lambda n Reaction in Momentum Range 470-650 MeV/c

The differential cross sections of the Sigma(-) p -> Lambda n reaction were measured accurately for the Sigma(-)momentum (p(Sigma)) ranging from 470 to 650 MeV/c at the J-PARC Hadron Experimental Facility. Precise angular information about the Sigma(-) p -> Lambda n reaction was obtained for the first time by detecting approximately 100 reaction events at each angular step of Delta cos theta = 0.1. The obtained differential cross sections show a slightly forward-peaking structure in the measured momentum regions. The cross sections integrated for -0.7 <= cos theta <= 1.0 were obtained as 22.5 +/- 0.68 [statistical error(stat.)] +/- 0.65 [systematic error(syst.)] mb and 15.8 +/- 0.83(stat) +/- 0.52(syst) mb for 470 < p(Sigma)(MeV/c) < 550 and 550 < p(Sigma)(MeV/c) < 650, respectively. These results show a drastic improvement compared with past measurements of the hyperon-proton scattering experiments. They will play essential roles in updating the theoretical models of the baryon-baryon interactions.