Rapidity dependence of the proton-to-pion ratio in Au+AuAu+Au and p+pp+p collisions at sNN=62.4 and 200 GeV

The proton-to-pion ratios measured in the BRAHMS experiment for Au+AuAu+Au and p+pp+p collisions at sNN=62.4 and 200 GeV are presented as a function of transverse momentum and collision centrality at selected pseudorapidities in the range of 0–3.8. A strong pseudorapidity dependence of these ratios is observed. We also compare the magnitude and pTpT-dependence of the p/π+p/π+ ratios measured in Au+AuAu+Au collisions at sNN=200 GeV and η≈2.2η≈2.2 with the same ratio measured at sNN=62.4 GeV and η=0η=0. The great similarity found between these ratios throughout the whole pTpT range (up to 2.2 GeV/c2.2 GeV/c) is consistent with particle ratios in A+AA+A collisions being described with grand-canonical distributions characterized by the baryo-chemical potential μBμB. At the collision energy of 62.4 GeV, we have observed a unique point in pseudorapidity, η=3.2η=3.2, where the p/π+p/π+ ratio is independent of the collision system size in a wide pTpT-range of 0.3⩽pT⩽1.8 GeV/c0.3⩽pT⩽1.8 GeV/c.