J/ψSuppression in Nucleus-Nucleus Collisions

TL;DR

This work factorized the process into a production of the cc- pairs convoluted with a transition probability into the observed J/psi mesons, and proposed a model that can fit all observed J /psi suppression data in hadron-nucleus and nucleus- nucleus collisions.

Abstract

We propose a model for the production and suppression of J/ψmesons in high-energy hadronic collisions. We factorized the process into a production of the $c\bar{c}$ pairs of relative momentum $k=k_c-k_{\bar{c}}$ convoluted with a transition probability from the produced $c\bar{c}$ pairs into the observed J/$ψ$ mesons. As the produced $c\bar{c}$ pairs exit the nuclear matter, the multiple scattering between the colored $c$ and $\bar{c}$ and the nuclear medium increases the square of the relative momentum between the $c$ and $\bar{c}, q^2=-k^2$, such that some of the $c\bar{c}$ pairs gain enough invariant mass to transmute into open charm states. With only one parameter, the amount of energy gained by the produced $c\bar{c}$ pair per unit length in the nuclear medium, our model can fit all observed J/ψsuppression data including recent NA50 data from Pb-Pb collisions.

Figures (2)

• Figure 1: Total J/$\psi$ cross sections in proton-nucleon collisions as a function of the colliding energy $\sqrt{S}$.
• Figure 2: Total J/$\psi$ cross sections with the branching ratio to $\mu^+\mu^-$ in proton-nucleon, hadron-nucleus and nucleus-nucleus collisions as a function of the effective nuclear medium length $L(A,B)$.