Directed flow of $\Lambda$ from heavy-ion collisions and hyperon puzzle of neutron stars

TL;DR

This study uses chiral effective field theory to analyze the directed flow of $\\Lambda$ hyperons in heavy-ion collisions, providing insights into hyperon potentials relevant for neutron star physics.

Contribution

It demonstrates that $\\Lambda$ potentials from $\\chi$EFT can reproduce experimental flow data, highlighting the importance of momentum dependence in hyperon potential modeling.

Findings

$\\Lambda$ potentials from $\\chi$EFT match STAR data.

Directed flow at large rapidities is sensitive to momentum dependence.

Understanding hyperon flow aids neutron star hyperon puzzle.

Abstract

We examine the $\Lambda$ potential from the chiral effective field theory ($\chi$EFT) via the $\Lambda$ directed flow from heavy-ion collisions. We implement the $\Lambda$ potential obtained from the $\chi$EFT in a vector potential version of relativistic quantum molecular dynamics. We find that the $\Lambda$ potentials obtained from the $\chi$EFT assuming weak momentum dependence reproduce the $\Lambda$ directed flow measured by the STAR collaboration in the Beam Energy Scan program. While the $\Lambda$ directed flow is not very sensitive to the density dependence of the potential, the directed flow at large rapidities is susceptible to the momentum dependence. Thus understanding the directed flow of hyperons in a wide range of beam energy and rapidity is helpful in understanding hyperon potentials in dense matter.