Evidence of Anisotropic Hydrodynamics from Recent Data on Pion and Kaon Emission in Heavy ion Collisions in the BM@N Experiment

Abstract— In this paper, a nonequilibrium hydrodynamic approach is developed in which the nonequilibrium state of the nuclear medium is described by jointly solving the kinetic equation and hydrodynamic equations. It is shown that, in accordance with the solution of the kinetic equation, the effective temperature may depend on the particle emission angle. This anisotropic hydrodynamics with hot spot identification agrees with the experimental data of the BM@N collaboration for pions and kaons in collisions of 40Ar ions with various targets at an energy of 3.2 GeV per nucleon. The first comparison of our approach with the experimental data obtained for the differential yields of protons, deuterons, and tritons in the BM@N Collaboration experiment with the same nuclei turned out to be quite successful.