Restoration of a Lost Symmetry -- Mass Reduction of the \eta' Mesons in   10^-22 Sec
  A particle called \eta' meson is found to reduce its mass in less than 10^-22 second in high energy heavy ion collisions at RHIC. Apparently this is the fastest mass reduction ever observed. This indicates the restoration of a lost symmetry of strong interactions in a hot and dense, hadronic matter. 
Tamas Csorgo, Robert Vertesi and Janos Sziklai
nucl-ex nucl-th