New Hypernuclei Measurements from STAR

TL;DR

This paper reports new measurements of hypernuclei yields and flow in heavy-ion collisions across various energies, providing insights into their production mechanisms and the effects of hypernuclear binding.

Contribution

It presents the first measurements of hypernuclei yields and flow at multiple energies, offering new data to understand hypernuclear production in heavy-ion collisions.

Findings

Yields of ${}^5_{\Lambda}$He, $^{4}_{\Lambda}$H, and $^{3}_{\Lambda}$H measured across different energies.

Results suggest differences in production mechanisms between models.

Directed flow of hypernuclei analyzed.

Abstract

Hypernuclei are bound states of hyperons (Y) and nucleons (N). Measurements on their yields can help us investigate their production mechanisms. In particular, the ${}^5_{\Lambda}$He and $^{4}_{\Lambda}$H(e) are substantially tighter bound compared to the $^{3}_{\Lambda}$H. The large radius of the $^{3}_{\Lambda}$H leads to suppression in coalescence models, but not in the thermal model where the size of the nucleus does not play a role. As such, studying the $A=3$--5 hypernuclei yields allow us to extract information on the effects of hypernuclear binding on hypernuclei production in heavy-ion collisions. In these proceedings, we present measurements of ${}^5_{\Lambda}$He yields in Au+Au collisions at $\sqrt{s_{\rm NN}}=3.0$ GeV, $^{4}_{\Lambda}$H(e) yields in Au+Au collisions at $\sqrt{s_{\rm NN}}=3.0$--$4.5$ GeV, and $^{3}_{\Lambda}$H yields in Au+Au collisions at $\sqrt{s_{\rm NN}}=3$--$27$ GeV. Results on the directed flow of hypernuclei are also reported. The physics implications of these measurements are discussed.