Net-proton probability distribution in heavy ion collisions

We compute net-proton probability distributions in heavy ion collisions within the hadron resonance gas model. The model results are compared with data taken by the STAR Collaboration in Au-Au collisions at √sNN=200 GeV for different centralities and for the central energy bin at √sNN=39 GeV. We show that, in central Au-Au collisions at √sNN=39 GeV, the measured distribution is consistent with the hadron resonance gas model but differs from the predictions of the model at √sNN=200 GeV. At the highest energy, deviations from model results are smaller for peripheral collisions. We argue that such properties of probability distributions are expected if the freeze-out conditions probed by fluctuations are located close to the QCD crossover transition.