Chemical equilibration of $π$, $ρ$ and $ω$ mesons in ultra--relativistic nuclear collisions

Abstract

I estimate the degree of local chemical equilibration for $π$, $ρ$ and $ω$ mesons in ultra--relativistic nuclear collisions. The $π$ and $ρ$ mesons remain near chemical equilibrium in all cases, while the $ω$ meson density is typically 30--50\% higher than the equilibrium value for O+Ag collisions at $\sqrt{s}=20$ GeV. If chemical reactions are turned off, the $ω$ meson density is much larger, 2.5--3 times its equilibrium value. Thus, $ω$ mesons may provide the most sensitive tests for the degree of chemical equilibration in nuclear collisions.