Universal anti-baryon density in e+e-,γp, pp, pA and AA collisions

الأصل · EN

We compiled the systematical measurements of anti-nucleus production in ultra-relativistic heavy ion collisions as well as those in pp, pp, γp and e⁺e⁻ at various beam energies. The anti-baryon phase space density inferred from d/p ratio in A+A, p+A, pp(p) and γp collisions is found to follow a universal distribution as a function of center of mass of beam energy and can be described in a statistical model. We demonstrated that anti-baryon density in all the collisions is the highest when the collisions are dominated by the processes of g+g or q+g. In e+e- collisions at LEP, the cross section of qqg is suppressed by a factor of strong coupling constant αₛ relative to qq. This can consistently explain the d suppression observed by ALEPH relative to that in e+e-→ ggg by ARGUS. We discuss the implications to the baryon enhancement at high transverse momentum at RHIC when jet is quenched.