Baryon-antibaryon production asymmetry in relativistic heavy ion collisions

Experimental data at Relativistic Heavy Ion Collider and Super Proton Synchrotron energies suggest a systematic correlation between yield ratio (p) over bar /p and K-/K+, which reveal some universality of hadron production in relativistic heavy ion collisions. We propose an explanation based on the quark combination mechanism that focuses on the production asymmetry between baryons and antibaryons. We start from the basic ideas of quark combination to carry out a general analysis of the properties of the global production of baryons and mesons and obtain the yields of baryons, antibaryons, and mesons as functions of the number of constituent quarks and antiquarks just before hadronization. In particular, we study effects of quark-antiquark asymmetry on the ratio of (anti-)baryons to mesons and that of antibaryons to baryons. We use these formula to well explain the data of (p) over bar /p and K-/K+ at different of collision energies and rapidities and suggest further measurements at moderate RHIC energies in the mid-forward rapidity regions to make the decisive test of this universality.