Antimatter ${}_{\hat{I}}^4›$H Hypernucleus Production and the ${}_{\hat{I}}^3›$H/${}^3$He Puzzle in Relativistic Heavy-Ion Collisions

Abstract

We show that the measured yield ratio ${}_{\hat{I}}^3›$H/${}^3$He (${}_{\overline{\hat{I}}›}^3\overline{\text{H}}$/${}^3\overline{\text{He}}$) in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV and in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV can be understood within a covariant coalescence model if (anti-)$\hat{I}›$ particles freeze out earlier than (anti-)nucleons but their relative freezeout time is closer at $\sqrt{s_{NN}}=2.76$ TeV than at $\sqrt{s_{NN}}=200$ GeV. The earlier (anti-)$\hat{I}›$ freezeout can significantly enhance the yield of (anti)hypernucleus ${}_{\hat{I}}^4›$H (${}_{\overline{\hat{I}}›}^4\overline{\text{H}}$), leading to that ${}_{\overline{\hat{I}}›}^4\overline{\text{H}}$ has a comparable abundance with ${}^4\overline{\text{He}}$ and thus provides an easily measured antimatter candidate heavier than ${}^4\overline{\text{He}}$. The future measurement on ${}_{\hat{I}}^4›$H (${}_{\overline{\hat{I}}›}^4\overline{\text{H}}$) would be very useful to understand the (anti-)$\hat{I}›$ freezeout dynamics and the production mechanism of (anti)hypernuclei in relativistic heavy-ion collisions.

7 pages, 4 figures, 2 tables. Significantly expanded to include some details and discussions. Accepted version to appear in PRC