Universal anti-baryon density in $e^+e^-$,$gamma p$, pp, pA and AA collisions

We compiled the systematical measurements of anti-nucleus production in ultra-relativistic heavy ion collisions as well as those in $pp$, $pbar{p}$, $gamma p$ and $e^{+}e^{-}$ at various beam energies. The anti-baryon phase space density inferred from $bar{d}/bar{p}$ ratio in $A+A$, $p+A$, $pp(bar{p})$ and $gamma p$ 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 $bar{q}+g$. In $e^+e^-$ collisions at LEP, the cross section of $qbar{q}g$ is suppressed by a factor of strong coupling constant $alpha_s$ relative to $qbar{q}$. This can consistently explain the $bar{d}$ suppression observed by ALEPH relative to that in $e^+e^-to ggg$ by ARGUS. We discuss the implications to the baryon enhancement at high transverse momentum at RHIC when jet is quenched.