Speaker
Description
The production of charmonium and its suppression in heavy-ion collisions is an ideal probe to explore the Quark-Gluon Plasma (QGP) in the laboratory. Suppression can also take place in hadron-nucleus collisions due to cold nuclear matter (CNM). The hadron-nucleus collisions are therefore important as they help disentangling the effects of the QGP from those due to CNM. The Charmonium production in hA collisions at fixed-target SPS energies is sensitive to the CNM effects like the nPDFs, and the partonic energy loss in nuclear matter.
The double differential ($x_{\rm F}$, $p_{\rm T}$) cross sections of J/$\psi$ production have been measured by the COMPASS collaboration in hA collisions at $\sqrt{s} = 18.9$ GeV. A negative pion beam with a momentum of 190 GeV/c was impinging on ammonia, aluminum, and tungsten targets.
The preliminary results for the ratios of heavy to light targets show strong suppression towards high $x_{\rm F}$ and low $p_{\rm T}$, indicating the presence of energy loss effects. A dependence with $p_{\rm T}$ is also investigated to study the nuclear $p_{\rm T}$-broadening effects. The results will be compared to the available fixed-target measurements and will be followed by the comparison with theoretical model predictions.
| Session | Heavy Ions and QCD |
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