Search for QCD critical point by transverse velocity dependence of anti-deuteron to deuteron ratio *

Abstract

Abstract We propose the transverse velocity ( ) dependence of the anti-deuteron to deuteron ratio as a new observable to search for the QCD critical point in heavy-ion collisions. The QCD critical point can attract the system evolution trajectory in the QCD phase diagram, which is known as the focusing effect. To quantify this effect, we employ the thermal and hadronic transport model to simulate the dynamical particle emission along a hypothetical focusing trajectory near the critical point. We found that the focusing effect can lead to anomalous dependence on , and ratios. We examined the dependence of and ratios of central Au+Au collisions at 7.7 to 200 GeV measured by the STAR experiment at RHIC. Surprisingly, we only observe a negative slope in dependence of ratio at 19.6 GeV, which indicates the trajectory evolution has passed through the critical region. In the future, we could constrain the location of the critical point and/or width of the critical region by conducting precise measurements on the dependence of the ratio at different energies and rapidity.