QCD sum rules for J/psi in the nuclear medium: calculation of the Wilson coefficients of gluon operators up to dimension 6

We calculate the Wilson coefficients of all dimension-6 gluon operators with nonzero spin in the correlation function between two heavy vector currents. For the twist-4 part, we first identify the three independent gluon operators, and then proceed with the calculation of the Wilson coefficients using the fixed-point gauge. Together with the previous calculation of the Wilson coefficients for the dimension-6 scalar gluon operators by Nikolaev and Radyushkin, our result completes the List of all the Wilson coefficients of dimension-6 gluon operators in the correlation function between heavy vector currents. We apply our results to investigate the mass of J/psi in nuclear matter using QCD sum rules. Using an upper-bound estimate on the matrix elements of the dimension-6 gluon operators to linear order in density, we find that the density-dependent contribution from dimension-6 operators is less than 30% of the dimension-4 operators with opposite sign. The final result gives about -4 MeV mass shift for the charmonium at rest in nuclear matter. (C) 2001 Elsevier Science B.V. All rights reserved.