Empirical regularities in the $x$--dependence of nuclear J/Psi suppression

Abstract

The measured ratios $R(x,A_1/A_2)$ for $J/\Psi$, $\Psi'$ and $\mu^+\mu^-$ production on two different targets $A_1, A_2$ as a function of the fractional momentum $x$ of the final state are well fit with a very simple functional form having three adjustable parameters. An empirical relation is found between the three parameters of the fit. The deduced $J/\Psi$ absorption cross sections $\sigma_{abs}$ cluster around two values of which only $\sigma_{abs} = 5.8 \pm 0.2$ mb seems acceptable.