Transverse Velocity Dependence of the Proton-Antiproton Ratio as a Signature of the QCD Critical Point

The presence of a critical point in the QCD phase diagram can deform the trajectories describing the evolution of the expanding fireball in the μ_B-T phase diagram. If the average emission time of hadrons is a function of transverse velocity, as microscopic simulations of the hadronic freeze-out dynamics suggest, the deformation of the hydrodynamic trajectories will change the transverse velocity (β_T) dependence of the proton-antiproton ratio when the fireball passes in the vicinity of the critical point. An unusual β_T dependence of the p̅ /p ratio in a narrow beam energy window would thus signal the presence of the critical point.