Understanding the $p/\pi$ ratio at LHC due to QCD mass spectrum
  Thermal fits have consistently reproduced the experimental particles yields of heavy ion collisions, however, the proton to pion ratio from ALICE Pb+Pb $\sqrt{s_{NN}}=2.76$ TeV is over-predicted by thermal models- known at the $p/\pi$ puzzle. Here we test the relevance of the extended mass spectrum, i.e., include Hagedorn states (resonances that follow an exponential mass spectrum and have very short life times) on the $p/\pi$ puzzle. We find that the extended mass spectrum is able to reproduce particle ratios at both RHIC and the LHC as well as being able to match the lower $p/\pi$ ratio at the LHC through dynamical chemical equilibration. 
Jacquelyn Noronha-Hostler and Carsten Greiner
nucl-th hep-ph