Particle ratios as a probe of the QCD critical temperature

We show how the measured particle ratios can be used to provide nontrivial information about the critical temperature of the QCD phase transition. This is obtained by including the effects of highly massive Hagedorn resonances on statistical models, which are used to describe hadronic yields. The inclusion of Hagedorn states creates a dependence of the thermal fits on the Hagedorn temperature, TH, which is assumed to be equal to Tc, and leads to an overall improvement of thermal fits. We find that for Au+Au collisions at the Relativistic Heavy Ion Collider at √sNN=200 GeV the best square fit measure, χ2, occurs at Tc~176 MeV and produces a chemical freeze-out temperature of 172.6 MeV and a baryon chemical potential of 39.7 MeV.