Towards resolving the Λ 3 H lifetime puzzle

摘要

RecentΛ3H lifetime measurements in relativistic heavy ion collision experiments have yielded values shorter by (30±8)% than the free Λ lifetimeτΛ, thereby questioning the naive expectationτ(HΛ3)≈τΛfor a weakly bound Λ hyperon. Here we apply the closure approximation introduced by Dalitz and coworkers to evaluate theΛ3H lifetime, usingΛ3H wavefunctions generated by solving three-body Faddeev equations. Our result, disregarding pion final-state interaction (FSI), isτ(HΛ3)=(0.90±0.01)τΛ. In contrast to previous works, pion FSI is found attractive, reducing furtherτ(HΛ3)toτ(HΛ3)=(0.81±0.02)τΛ. We also evaluate for the first timeτ(nΛ3), finding it considerably longer thanτΛ, contrary to the shorter lifetime values suggested by the GSI HypHI experiment for this controversial hypernucleus.