Global Polarization of (Anti-)Hypertriton in Heavy-Ion Collisions

Particles of non-zero spin produced in non-central heavy-ion collisions are expected to be polarized along the direction perpendicular to the reaction plane because of their spin-orbit interactions in the produced matter, and this has indeed been observed for many hyperons and vector mesons. Here, we show that the hypertriton ($^3_\Lambda\text{H}$), which is the lightest hypernucleus, is also polarized in these collisions. Using the coalescence model based on the kinetic freezeout baryons for light (hyper-)nuclei production, we find that the angular distribution of the decay product of polarized $^3_\Lambda\text{H}$ is highly sensitive to the spin configuration of its wavefunction, providing a novel way to determine its spin structure. We also predict the beam energy dependence of $^3_\Lambda\text{H}$ and ${^3_{\bar{\Lambda}}}\overline{\rm H}$ polarizations in heavy-ion collisions from a few GeV to several TeV based on the measured $\Lambda$ and $\bar{\Lambda}$ polarizations. We further discuss the possibility of studying the spin correlations among nucleons and $\Lambda$ hyperons in the produced hadronic matter from the measured $^3_\Lambda\text{H}$ polarization in non-central heavy-ion collisions.
Comment: 6 pages, 2 figures