The rapidity dependence of the proton - to - pion ratio in Au + Au and p + p collisions at √ s NN = 62 . 4 and 200

The proton-to-pion yield ratios measured in the BRAHMS experiment for Au+Au and p+p collisions at √ s NN = 62.4 GeV and √ s NN = 200 GeV are presented as a function of transverse momentum and collision centrality within the pseudorapidity range 0 ≤ η ≤ 3.8. A strong pseu-dorapidity dependence of these ratios is observed. In Au+Au collisions at √ s NN = 200 GeV, η ≈ 2.2, and at √ s NN = 62.4 GeV, η = 0, the bulk medium can be characterized by the common value of µ B ≈ 65 MeV. The p/π + (p T) ratios measured for these two selections display a striking agreement in the p T range covered (up to 2.2 GeV/c). At collision energy of 62.4 GeV and forward pseudorapidity we found a crossing point of p/π + ratios measured in central and semi-peripheral Au+Au and in p+p reactions. The crossing occurs in the narrow η bin around value of 3.2, simultaneously in the whole covered p T range (0.3 GeV/c < p T < 1.8 GeV/c).