The K/pi ratio and the lifespan of the fireball
  We construct a hadronic kinetic model for description of excitation functions of multiplicity ratios K+/pi+, K-/pi-, and Lambda/pi. It is shown that the model is able to describe data rather well under the assumption that the total lifespan of the fireball is decreasing function of the collision energy for SPS energies above 30 AGeV. Thus in order to identify the onset of deconfinement the proposed model will have to be checked against other kinds of data until hadronic description can be safely falsified. 
Boris Tomasik and Evgeni E Kolomeitsev