Four-point current-current interactions for nonmesonic weak decay of hypernuclei He-4(Lambda), He-5(Lambda) and C-12(Lambda)

摘要

One of the most urgent issues in Lambda-hypernuclear physics today is how to resolve the difficulty in explaining the total and partial decay rates Gamma(nm) = Gamma(n) + Gamma(p) and the ratio Gamma(n)/Gamma(p) in the nonmesonic weak decay (NMWD) of hypernuclei [1]. There have been a few theoretical treatments of this isuue: (1) various meson-exchange models, especially pion-exchange models (OPE) with the Delta I = 1/2 rule [2], (3) hybrid quark models [3], and (3) phenomenological models [4]. Yet, a complete understanding of NMWD has not been achieved. Other mechanisms might still be needed to resolve the issue. Here, we would like to suggest a new mechanism to resolve the nonmesonic decay problem. We believe, in addition to the pion-exchange interaction [2], the following 4-point current-current interactions (4P) play an important role [5]. [References: 15]