Towards resolving the Λ3H lifetime puzzle

Abstract

Recent Λ3H lifetime measurements in relativistic heavy ion collision experiments have yielded values shorter by (30±8)% than the free Λ lifetime τΛ, thereby questioning the naive expectation τ(HΛ3)≈τΛ for a weakly bound Λ hyperon. Here we apply the closure approximation introduced by Dalitz and coworkers to evaluate the Λ3H lifetime, using Λ3H wavefunctions generated by solving three-body Faddeev equations. Our result, disregarding pion final-state interaction (FSI), is τ(HΛ3)=(0.90±0.01)τΛ. In contrast to previous works, pion FSI is found attractive, reducing further τ(HΛ3) to τ(HΛ3)=(0.81±0.02)τΛ. We also evaluate for the first time τ(nΛ3), finding it considerably longer than τΛ, contrary to the shorter lifetime values suggested by the GSI HypHI experiment for this controversial hypernucleus. Keywords: Light Λ hypernuclei, Hypertriton lifetime, Faddeev calculations