Quantum Opacity, the RHIC HBT Puzzle, and the Chiral Phase Transition
  We present a relativistic quantum mechanical treatment of opacity and refractive effects that allows reproduction of observables measured in two-pion (HBT) interferometry and pion spectra at RHIC. The inferred emission duration is substantial. The results are consistent with the emission of pions from a system that has a restored chiral symmetry. 
John G. Cramer, Gerald A. Miller, Jackson M. S. Wu, Jin-Hee Yoon