Properties of quarkonia atT_c

Abstract

Abstract. We discuss how the spectral changes of quarkonia at T c can reflect the "critical" behaviour of QCD phase transition. Starting from the temperature dependencies of the energy density and pressure from lattice QCD calculation, we extract the temperature dependencies of the scalar and spin 2 gluon condensates near T c . We also parameterize these changes into the electric and magnetic condensate near T c . While the magnetic condensate hardly changes across T c , we find that the electric condensate increases abruptly above T c . Similar abrupt change is also seen in the scalar condensate. Using the QCD second-order Stark effect and QCD sum rules, we show that these sudden changes induce equally abrupt changes in the mass and width of J/ψ, both of which are larger than 100 MeV at slightly above T c .

Properties of $J/ψ$ at $T_c$: QCD second-order Stark effect

“…Moreover, as was shown in Ref. [31], G 0 (T ) extracted from a recent full lattice calculation of the interaction measure [32] after subtracting the quark contributions, and then dividing by a factor of (1+ 5 12 n f ) appearing in the beta function, shows that the change of the magnitude near T c is remarkably similar to that of the pure gauge theory. Hence the main input for our result does not change much even in the presence of dynamical quarks.…”