Towards resolving the Λ3 H lifetime puzzle

Abstract

Recent Λ3 H lifetime measurements in relativistic heavy ion collision experiments have yielded values shorter by (30±8)% than the free Λ lifetime τ Λ , thereby questioning the naive expectation τ(HΛ3)≈τ Λ for a weakly bound Λ hyperon. Here we apply the closure approximation introduced by Dalitz and coworkers to evaluate the Λ3 H lifetime, using Λ3 H wavefunctions generated by solving three-body Faddeev equations. Our result, disregarding pion final-state interaction (FSI), is τ(HΛ3)=(0.90±0.01)τ Λ . In contrast to previous works, pion FSI is found attractive, reducing further τ(HΛ3) to τ(HΛ3)=(0.81±0.02)τ Λ . We also evaluate for the first time τ(nΛ3), finding it considerably longer than τ Λ , contrary to the shorter lifetime values suggested by the GSI HypHI experiment for this controversial hypernucleus.