Evaluations of freeze-out parameters from ${{dE_{T}} \over {d\eta}} / {{dN_{ch}} \over {d\eta}}$ ratio measured at RHIC and SPS

Abstract

In the presented paper curves of constant $\epsilon_{T} / n_{charged}$ are calculated in $T-\mu_{B}$ plane, in the framework of a single-freeze-out thermal hadron gas model. The ratio is a theoretical equivalent of ${{dE_{T}} \over {d\eta}}_{\mid \eta=0} / {{dN_{ch}} \over {d\eta}}_{\mid \eta=0}$ measured at RHIC and SPS. In both $\epsilon_{T}$ and $n_{charged}$ decays of hadron resonances are taken into account. The freeze-out temperature $T_{f.o.}=156_{-11}^{+14}$ MeV is obtained for RHIC, whereas $T_{f.o.}=134-140$ MeV is evaluated for SPS.