Feasibility study for measurement of beta-decay rates of Λ hypernuclei

Abstract

The baryon structure may be modified in nuclear medium. The quark meson coupling model predicts that the beta decay rate of a Λ hyperon in Λ hypernuclei decreases by 20% at maximum. We propose an experiment to precisely measure the beta-decay rate of 5ΛHe at J-PARC via the (π+, K+) reaction. A feasibility study via GEANT4 simulation has been done, showing that the background can be suppressed down to ~ 3.9% of the betadecay electron yield, using a calorimeter covering the whole solid angle around the target. The measurement of the beta-decay of a Λ in a nucleus is found to be feasible.