The Transverse Momentum Dependence of Anomalous $J/\psi$ Suppression

Abstract

In proton-nucleus and nucleus-nucleus collisions up to central $S-U$ interactions, the $P_T$-dependence of $J/\psi$ production is determined by initial state parton scattering and pre-resonance nuclear absorption (``normal" $J/\psi$ suppression). The ``anomalous" $J/\psi$ suppression in $Pb-Pb$ collisions must reduce the normal $P_T$ broadening, since it occurs mainly in the central part of the interaction region, where also initial state parton scattering and nuclear absorption are strongest. We thus expect for $< P_T^2 >$ in $Pb-Pb$ collisions a turn-over and decrease with increasing $E_T$.