Nonmesonic hyperon weak decay spectra in ¹²_ΛC

Abstract

We study the nonmesonic weak decay (NMWD) ΛN → nN of the ¹²_ΛC hypernucleus induced by the nucleon N = n,p with transition rate ΓN. The nuclear process is described by the interplay of two models; one describing the NMWD of hyperon Λ in the nuclear environment, and the other taking into account the Final State Interaction (FSI) of the two outgoing nucleons with the residual nucleus. The first one is done in the framework of the Independent-Particle Shell-Model (IPSM), with the decay dynamics represented by the exchange of π+η+K+ρ+ω+ K*mesons with usual parametrization. For the second one is used a time dependent multicollisional intranuclear cascade schema (implemented in the CRISP code - Collaboration Rio-São Paulo). The results obtained for inclusive and exclusive kinetic energy spectra, and the angular correlation are compared with recent data from KEK and FINUDA experiments. The calculated ratio (Γ n /Γ p ) FSI , between the numbers of emitted back-to-back nn and np pairs, is in good agreement with the experimental data.