Measurement of the Hypertriton Properties and Production with ALICE

The hypertriton (3 ΛH) is a bound state of a proton, a neutron, and a Λ baryon. Studying its internal structure is crucial to investigate the hyperon–nucleon (Y –N) strong interaction and offers insights into the inner core of neutron stars, where Λ production is favoured. Measuring precisely the 3 ΛH lifetime, τ3 ΛH, and Λ separation energy, BΛ, provide a powerful tool for constraining the parameters of the Y –N potential, as τ3 ΛH and BΛ directly reflect the strength of the Y –N interaction. The most precise measurements to date of τ3 ΛH and BΛ are obtained by the ALICE Collaboration, using the data sample of Pb–Pb collisions at a centre-of-mass energy per nucleon pair of √ sNN = 5.02 TeV. These measurements strongly support the loosely-bound nature of 3 ΛH and shed light on the Y –N interaction. Furthermore, the weakly bound nature of the 3 ΛH has important implications on our understanding of the nucleosynthesis mechanism in hadronic collisions. Indeed, the large size of the 3 ΛH wave function determines a large separation between the nuclei production models at low charged-particle multiplicity. For this reason, the first measurement of the production of 3 ΛH in p–Pb collisions at √ sNN = 5.02 TeV performed by ALICE represents an ideal probe for discriminating between the nuclei production mechanisms in high-energy hadron–hadron collisions.