J/ψ dissociation by pions in QCD

We compute the J/ψ π→charmed mesons cross section using QCD sum rules. This cross section is important to distinguish the suppression in the production of J/ψ through the dissociation by comoving pions and through the formation of quark–gluon plasma. Our sum rules for the J/ψ π→D̄D∗, DD̄∗, D̄∗D∗ and D̄D hadronic matrix elements are constructed by using vacuum–pion correlation functions, and we work up to twist-4. After doing a thermal average we get 〈σπJ/ψv〉∼0.2–0.4 mb at T=150 MeV.