Kinematic distributions and nuclear effects of $J/\psi$ production in 920 GeV fixed-target proton-nucleus collisions

Abstract

Measurements of the kinematic distributions of $J/\psi$ mesons produced in $p-$C, $p-$Ti and $p-$W collisions at $\sqrt{s}=41.6\mathrm{GeV}$ in the Feynman-$x$ region $-0.34<x_F<0.14$ and for transverse momentum up to $p_T=5.4\mathrm{GeV}/c$ are presented. The $x_F$ and $p_T$ dependencies of the nuclear suppression parameter, $\alpha$, are also given. The results are based on $2.4\cdot 10^5$ $J/\psi$ mesons in both the $e^{+}{e}^{-}$ and ${\mu }^{+}{\mu }^{-}$ decay channels. The data have been collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The measurement explores the negative region of $x_F$ for the first time. The average value of $\alpha$ in the measured $x_F$ region is $0.981\pm 0.015$. The data suggest that the strong nuclear suppression of $J/\psi$ production previously observed at high $x_F$ turns into an enhancement at negative $x_F$.

19 pages, 11 figures, 6 tables

References in corpus (3)

• Angular distributions of leptons from J/psi's produced in 920 GeV fixed-target proton-nucleus collisions
• The Outer Tracker Detector of the HERA-B Experiment. Part III: Operation and Performance
• Luminosity determination at HERA-B

Cited by in corpus (2)

• Energy dependence of J/psi absorption in proton-nucleus collisions
• Angular distributions of leptons from J/psi's produced in 920 GeV fixed-target proton-nucleus collisions