Speaker
Description
Hypernuclei are bound nuclear systems of correlated nucleons and hyperons. Therefore, the production of hypernuclei in heavy-ion collisions provides an experimental avenue for studying the hyperon$-$nucleon (Y-N) interaction, which is an important ingredient, not only in the equation-of-state (EoS) of astrophysical objects such as neutron stars but also in the description of the hadronic phase of a heavy-ion collision. The strength of the Y-N interaction can be investigated by measuring the properties of hypernuclei. For example, light $\Lambda$-hypernuclei containing one hyperon are conventionally understood as a weakly bound system of a $\Lambda$ and a nucleus, suggesting their lifetimes are close to the free-$\Lambda$ lifetime.
In heavy-ion collisions, light hypernuclei are expected to be abundantly produced at low energies due to the high baryon density. In this poster, we will report precise lifetime measurements of $^3_{\Lambda}H$, $^4_{\Lambda}H$ and $^4_{\Lambda}He$ in Au+Au collisions at $\sqrt{s_{NN}}$ = 3 GeV and 7.2 GeV, recorded by the STAR experiment at RHIC in the fixed-target mode in 2018. The results will be compared with model calculations and physics implications will be discussed.
