Collision Energy Dependence of Hypertriton Production in Au+Au Collisions at RHIC

The STAR Collaboration reports measurements of the collision energy dependence of hypertriton (${}^{3}_Λ$H) transverse momentum spectra and $p_{\rm T}$-integrated yields at mid-rapidity ($|y|<$0.5) in Au+Au collisions at 11 collision energies between 3.2 and 27\,GeV. The measured ${}^{3}_Λ$H yields and ${}^{3}_Λ$H/$Λ$ yields ratio in central collisions increase strongly with decreasing collision energy, and are a factor of $\sim$2 lower than thermal model predictions at this energy range. The mean $p_{\rm T}$ of ${}^{3}_Λ$H is lower than the Blast-Wave expectation using the freeze-out parameters from light hadrons. Furthermore, the observed double ratio $({}^{3}_Λ{\rm{H}}/Λ)/(t/p)$ maintains a constant value of $\sim$0.4 across the measured energy range. Within the coalescence framework, this ratio directly reflects the significantly suppressed formation probability of the weakly-bound hypertriton relative to the triton, which results from the weaker hyperon-nucleon interaction compared with the nucleon-nucleon interaction.