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

Abstract

The measured ratios $R(x,A_1/A_2)$ for $J/\Psi$, ${\Psi }^{\prime }$ 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.

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