  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 sqrt(s_{NN})= 200 GeV
for different centralities. We show that in peripheral Au-Au collisions the
measured distributions, and the resulting first four moments of net-proton
fluctuations, are consistent with results obtained from the hadron resonance
gas model. However, data taken in central Au-Au collisions differ from the
predictions of the model. The observed deviations can not be attributed to
uncertainties in model parameters. We discuss possible interpretations of the
observed deviations.
