Orateur
Description
In heavy-ion collisions, the production mechanism of hypernuclei, bound states of hyperons and nucleons, is still not fully understood. Recent theoretical model calculations show that a systematic measurement of the multiplicity dependence of yield ratios, such as $^{3}_{\Lambda}\mathrm{H}/\Lambda$ and $\mathrm{S}_{\rm 3}=(^{3}_{\Lambda}\mathrm{H}/^{3}\mathrm{He})/(\Lambda/\mathrm{p})$, can provide strong distinguishing power between different production mechanisms and offer insights into the possible connection between hypernuclei production yields and their internal structure. In 2018, STAR recorded a huge sample of about 4 billion minimum bias events from Zr+Zr and Ru+Ru collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV, enabling a detailed investigation of the multiplicity dependence of hyperon and hypertriton production.
In this presentation, we present new measurements on hyperons ($\Lambda, \bar{\Lambda}$ and $\Xi^{-}, \bar{\Xi}^{+}$) and hypertriton, including their transverse momentum ($p_\mathrm{T}$) spectra and $p_\mathrm{T}$-integrated yields ($\mathrm{d}N/\mathrm{d}y$), in four different centrality classes of Zr+Zr and Ru+Ru collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV. The hyperon yields will be compared to those in Au+Au collisions to study the system size dependence of strangeness production. The yield ratios of $^{3}_{\Lambda}\mathrm{H}/\Lambda$ and $\mathrm{S}_{3}$ will be shown as a function of multiplicity and compared with model calculations. Physics implications on hypernuclei production mechanism as well as Y-N interaction will be discussed.
