Particle Ratios within EPOS, UrQMD and Thermal Models at AGS, SPS and RHIC Energies

Abstract

The particle ratios $k^{+}/{\pi }^{+}$, ${\pi }^{-}/K^{-}$, $\bar{p}/{\pi }^{-}$, $\Lambda /{\pi }^{-}$, $\Omega /{\pi }^{-}$, $p/{\pi }^{+}$, ${\pi }^{-}/{\pi }^{+}$, $K^{-}/K^{+}$, $\bar{p}/p$, $\bar{\Lambda }/\Lambda$, $\bar{\Sigma }/\Sigma$, $\bar{\Omega }/\Omega$ measured at AGS, SPS and RHIC energies are compared with large statistical ensembles of $100,000$ events deduced from the CRMC EPOS $1.99$ and the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) hybrid model. In the UrQMD hybrid model two types of phase transitions are taken into account. All these are then confronted to the Hadron Resonance Gas Model. The two types of phase transitions are apparently indistinguishable. Apart from $k^{+}/{\pi }^{+}$, $k^{-}/{\pi }^{-}$, $\Omega /{\pi }^{-}$, $\bar{p}/{\pi }^{+}$, and $\bar{\Omega }/\Omega$, the UrQMD hybrid model agrees well with the CRMC EPOS $1.99$. Also, we conclude that the CRMC EPOS $1.99$ seems to largely underestimate $k^{+}/{\pi }^{+}$, $k^{-}/{\pi }^{-}$, $\Omega /{\pi }^{-}$, and $\bar{p}/{\pi }^{+}$.

Comments: 8 pages, 2 figures, submitted to JETP