We report precision measurements of hypernuclei ${}^3_\Lambda \rm{H}$ and${}^4_\Lambda \rm{H}$ lifetimes obtained from Au+Au collisions at \snn =3.0\,GeV and 7.2\,GeV collected by the STAR experiment at RHIC, and the firstmeasurement of ${}^3_\Lambda \rm{H}$ and ${}^4_\Lambda \rm{H}$ mid-rapidityyields in Au+Au collisions at \snn = 3.0\,GeV. ${}^3_\Lambda \rm{H}$ and${}^4_\Lambda \rm{H}$, being the two simplest bound states composed of hyperonsand nucleons, are cornerstones in the field of hypernuclear physics. Theirlifetimes are measured to be $221\pm15(\rm stat.)\pm19(\rm syst.)$\,ps for${}^3_\Lambda \rm{H}$ and $218\pm6(\rm stat.)\pm13(\rm syst.)$\,ps for${}^4_\Lambda \rm{H}$. The $p_T$-integrated yields of ${}^3_\Lambda \rm{H}$ and${}^4_\Lambda \rm{H}$ are presented in different centrality and rapidityintervals. It is observed that the shape of the rapidity distribution of${}^4_\Lambda \rm{H}$ is different for 0--10\% and 10--50\% centralitycollisions. Thermal model calculations, using the canonical ensemble forstrangeness, describes the ${}^3_\Lambda \rm{H}$ yield well, whileunderestimating the ${}^4_\Lambda \rm{H}$ yield. Transport models, combiningbaryonic mean-field and coalescence (JAM) or utilizing dynamical clusterformation via baryonic interactions (PHQMD) for light nuclei and hypernucleiproduction, approximately describe the measured ${}^3_\Lambda \rm{H}$ and${}^4_\Lambda \rm{H}$ yields. Our measurements provide means to preciselyassess our understanding of the fundamental baryonic interactions with strangequarks, which can impact our understanding of more complicated systemsinvolving hyperons, such as the interior of neutron stars or exotichypernuclei.

### Measurements of ${}^3_Λ\rm{H}$ and ${}^4_Λ\rm{H}$ Lifetimes and Yields in Au+Au Collisions in the High Baryon Density Region

#### Abstract

We report precision measurements of hypernuclei ${}^3_\Lambda \rm{H}$ and${}^4_\Lambda \rm{H}$ lifetimes obtained from Au+Au collisions at \snn =3.0\,GeV and 7.2\,GeV collected by the STAR experiment at RHIC, and the firstmeasurement of ${}^3_\Lambda \rm{H}$ and ${}^4_\Lambda \rm{H}$ mid-rapidityyields in Au+Au collisions at \snn = 3.0\,GeV. ${}^3_\Lambda \rm{H}$ and${}^4_\Lambda \rm{H}$, being the two simplest bound states composed of hyperonsand nucleons, are cornerstones in the field of hypernuclear physics. Theirlifetimes are measured to be $221\pm15(\rm stat.)\pm19(\rm syst.)$\,ps for${}^3_\Lambda \rm{H}$ and $218\pm6(\rm stat.)\pm13(\rm syst.)$\,ps for${}^4_\Lambda \rm{H}$. The $p_T$-integrated yields of ${}^3_\Lambda \rm{H}$ and${}^4_\Lambda \rm{H}$ are presented in different centrality and rapidityintervals. It is observed that the shape of the rapidity distribution of${}^4_\Lambda \rm{H}$ is different for 0--10\% and 10--50\% centralitycollisions. Thermal model calculations, using the canonical ensemble forstrangeness, describes the ${}^3_\Lambda \rm{H}$ yield well, whileunderestimating the ${}^4_\Lambda \rm{H}$ yield. Transport models, combiningbaryonic mean-field and coalescence (JAM) or utilizing dynamical clusterformation via baryonic interactions (PHQMD) for light nuclei and hypernucleiproduction, approximately describe the measured ${}^3_\Lambda \rm{H}$ and${}^4_\Lambda \rm{H}$ yields. Our measurements provide means to preciselyassess our understanding of the fundamental baryonic interactions with strangequarks, which can impact our understanding of more complicated systemsinvolving hyperons, such as the interior of neutron stars or exotichypernuclei.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11770/334099
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