Investigating the hyperon-nucleon strong interaction with a precision measurement of the hypertriton lifetime in ALICE

The hypertriton is a bound state of a proton, a neutron and a Λ baryon. Studying its internalstructure is crucial to investigate the hyperon–nucleon strong interaction and offers insights intothe inner core of neutron stars, where Λ production is favoured. One powerful way to investigatethe hypertriton’s internal structure is to measure precisely its lifetime. The hypertriton is anextremely loosely bound object with a lambda separation energy E_Λ of only 130 keV. Thereforethe hypertriton lifetime is expected to be close to the one of the free Λ. Thanks to the very largeset of Pb–Pb collision data collected during LHC Run 2, the ALICE collaboration has performedsystematic studies on the hypertriton lifetime. The hypertriton 2-body mesonic decay channel hasbeen studied with the help of machine learning techniques for the signal extraction. The precisionof the new ALICE results on the hypertriton lifetime is comparable with the current world averageand the measured lifetime value confirms the weakly-bound nature of the hypertriton.