Beam energy dependence of transverse momentum distribution and elliptic flow in Au-Au collisions using HYDJET++ model

Abstract

In this work, we present the particle ratios, transverse momentum spectra, and elliptic flow ($v_2$) of ${\pi }^{\pm },k^{\pm },$ $p$, and $\bar{p}$ in Au-Au collisions at $\sqrt{s_{NN}}=$ 62.4, 39.0, 27.0, 19.6 and 11.5 GeV using HYDJET++ model. The particle ratios match the experimental data that validates the Cleymans-Reidlich parameterization of freeze-out parameters at lower beam energies under the HYDJET++ framework. The lower collision energies produce a system of high baryon chemical potential (${\mu }_B$) and have a lower inelastic cross section. The interplay between these effects affects the overall shape of the $p_T$ spectra. The HYDJET++ model calculations for $p_T$ spectra agree well with the available experimental data. The invariant yield ratio of central and peripheral collisions is independent of beam energy. The elliptic flow is calculated based on the scaling between initial and final azimuthal spatial anisotropy ($k$). This interpretation of $v_2$ successfully describes the experimental data for all the collision energies studied in this work. The positive correlation of $k$ with beam energy leads to a small $v_2$ at lower collision energies. The hadrons containing strange quarks tend to have smaller values of $k$ than the non-strange hadrons.