We calculate the 2-loop partition function of QCD on the lattice, using the
Wilson formulation for gluons and the overlap-Dirac operator for fermions.
Direct by-products of our result are the 2-loop free energy and average
plaquette. Our calculation serves also as a prototype for further higher loop
calculations in the overlap formalism. We present our results as a function of
a free parameter M0β entering the overlap action; the dependence on the
number of colors N and fermionic flavors Nfβ is shown explicitly.Comment: 10 pages, 5 figures. Final version to appear in Physical Review D. A
missing overall factor was inserted in Eq. 12; it affects also Eq. 1