%0 Journal Article
%A Dobado González, Antonio
%A Llanes Estrada, Felipe José
%A Torres Rincón, Juan Miguel
%T Eta/s is critical (at phase transitions)
%D 2009
%@ 0094-243X
%U https://hdl.handle.net/20.500.14352/50645
%X The viscosity over entropy density ratio, or KSS number, can help isolate the critical point in the hadron phase-diagram in Relativistic Heavy Ion Collisions. We argue that this quantity does have a minimum at a phase transition or  crossover. Although indications from conventional non-relativistic gases point out to even a divergence in eta/s when the phase-transition is first-order, since the critical exponent is rather low, this will be more difficult to  ascertain in RHIC or FAIR. The experimental data are more likely to reveal a discontinuity for a first order phase transition or a smooth minimum at a crossover.
%~