Mean $p_t$ fluctuations from 2- and 4-particle correlations
  Recent results on event-by-event mean transverse momentum, $\mpt$, fluctuations in ultra-relativistic heavy ion collisions are briefly reviewed. We conclude that the observed fluctuations are in a rough agreement with that expected for the independent superposition of nucleon-nucleon collisions. We further discuss the possibility of the use of the forth order cumulants of the particle transverse momentum distribution in order to access the fluctuations related to collective phenomena. 
Sergei A. Voloshin