  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 first
measurement of ${}^3_\Lambda \rm{H}$ and ${}^4_\Lambda \rm{H}$ mid-rapidity
yields 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 hyperons
and nucleons, are cornerstones in the field of hypernuclear physics. Their
lifetimes 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 rapidity
intervals. It is observed that the shape of the rapidity distribution of
${}^4_\Lambda \rm{H}$ is different for 0--10\% and 10--50\% centrality
collisions. Thermal model calculations, using the canonical ensemble for
strangeness, describes the ${}^3_\Lambda \rm{H}$ yield well, while
underestimating the ${}^4_\Lambda \rm{H}$ yield. Transport models, combining
baryonic mean-field and coalescence (JAM) or utilizing dynamical cluster
formation via baryonic interactions (PHQMD) for light nuclei and hypernuclei
production, approximately describe the measured ${}^3_\Lambda \rm{H}$ and
${}^4_\Lambda \rm{H}$ yields. Our measurements provide means to precisely
assess our understanding of the fundamental baryonic interactions with strange
quarks, which can impact our understanding of more complicated systems
involving hyperons, such as the interior of neutron stars or exotic
hypernuclei.
