(Anti)hypertriton lifetime puzzle

Abstract

Most calculations on the lifetime of (anti)hypertriton gave a similar lifetime which is close to the lifetime of free Λ decays. However, recent measurements on (anti)hypertriton lifetime demonstrate a much short lifetime. All results for (anti)hypertriton lifetime by two-body decay channel of 3 He + π for Au+Au collision at RHIC, Pb+Pb collision at LHC and Li + C collisions at GSI show a significant short lifetime in comparison with lifetime of free Λ decays. However, theoretical interpretation remains puzzle.Hypernucleus provides an ideal environment to learn the hyperonnucleon interaction, which is responsible partly for the binding of hypernuclei and lifetime. Therefore, a meaurement of the precise lifetime of hypernucleus could provide a tool to investigate of hyeron-nucleon interaction [1][2][3][4][5][6][7]. The most simple hypernucleus is hypertriton, which is a bound state of a proton, a neutron, and a hyperon (Λ or Ξ), it is bound with respect to the Λ-d threshold by 0.136±0.05 MeV. In 2010, 3 Λ H, the antimatter partner of 3 Λ H, has been discovered at RHIC-STAR as the first antimatter hypernucleus [8] . The hypertriton decays weakly into mesonic and nonmesonic channels. The nonmesonic decay channels are 3 Λ H→ d + n and 3 Λ H→ p + n +n. In the mesonic decay mode there are more channels:

New directions in hypernuclear physics

“…It shows that their accuracies are similarly large and that the measured values overlap within the errors as summarised in Ref. 31 . To reach a more definitive conclusion on the value of the hypertriton lifetime, at least one more precise measurement is needed.…”