Speaker
Description
The production of light nuclei and hypernuclei in relativistic heavy-ion collisions provides a unique opportunity to investigate the formation mechanism of loosely bound states and the structure of hypernuclei. In particular, coalescence models predict a strong suppression of hypertriton (${}^{3}_{\Lambda}\mathrm{H}$) production relative to ${}^{3}\mathrm{He}$ in small collision systems because of the large spatial extent of the hypertriton wave function.
In this talk, we will present measurements of light nuclei ($t$, ${}^{3}\mathrm{He}$, and ${}^{3}\overline{\mathrm{He}}$) and hypernuclei (${}^{3}_{\Lambda}\mathrm{H}$ and ${}^{3}_{\bar{\Lambda}}\overline{\mathrm{H}}$) production at mid-rapidity in Ru+Ru and Zr+Zr collisions at $\sqrt{s_{\rm NN}}=200$ GeV with the STAR experiment. The multiplicity dependence of the yield ratios $N_tN_p/N_d^2$ and $S_{3} =(N_{{}^{3}_{\Lambda}\rm{H}}/N_{{}^{3}_{}\rm{He}})/(N_{\Lambda}/N_{p})$ will be discussed and compared with thermal and coalescence model calculations. The measurements show significant deviations from thermal-model expectations, while coalescence calculations incorporating realistic non-Gaussian wave functions for $d$ and ${}^{3}_{\Lambda}\mathrm{H}$ provide an improved description of the data. The results suggest that the hypertriton wave function has a larger short-distance $d$--$\Lambda$ probability than implied by a Gaussian ansatz, demonstrating the potential of heavy-ion production measurements as a probe of hypernuclear wave functions and the underlying hyperon--nucleon interaction.
