Search for the deeply bound K-pp state from the semi-inclusive forward-neutron spectrum in the in-flight K- reaction on helium-3

Abstract

semi-inclusive neutron missing-mass spectrum at lab n = 0 , no significant peak was observed in the region corresponding to K -pp binding energy larger than 80 MeV, where a bump structure has been reported in the p final state in different reactions. Assuming the state to be isotropically decaying into p, mass-dependent upper limits on the production cross section were determined to be 30-180, 70-250, and 100-270 b/sr, for the natural widths of 20, 60, and 100 MeV, respectively, at 95% confidence level.