Directed flow of Λ in high-energy heavy-ion collisions and Λ potential in dense nuclear matter

We investigate the sensitivity of the directed flow to the potential in midcentral Au + Au collisions at s₍₍3. 0--300. 16em{0ex}GeV. The potential obtained from the chiral effective field theory () is used in a microscopic transport model, a vector version of relativistic quantum molecular dynamics. We find that the density-dependent potentials, obtained from the assuming weak momentum dependence of the potential, reproduce the rapidity and the beam-energy dependence of the directed flow measured by the STAR collaboration in the beam energy scan program. Although the directed flow is insensitive to the density dependence of the potential, it is susceptible to the momentum dependence. We also show that a hydrodynamics picture based on the blast-wave model predicts a similarity of the proton, , and directed flows, but the directed flow of baryons slightly deviates from other baryons. We also show that the quark coalescence predicts different rapidity dependence of the directed flows for hyperons. These investigations suggest that measurements of a wide range of the rapidity dependence of the directed flow of hyperons may provide important information about the properties of hot and dense matter created in high-energy heavy-ion collisions.