PION LOOPS IN QUENCHED QUANTUM CHROMODYNAMICS

We calculate the divergences of the generating functional of quenched Chiral Perturbation Theory to one loop for a generic number of flavour s. The flavour number dependence of our result enlightens the mechanis m of quark loop cancellation in the quenched effective theory for any Green function or S matrix element. We also apply our results to pi pi scattering and evaluate the coefficient of the chiral log in the S-wa ve scattering lengths for the quenched case. (C) 1997 Elsevier Science B.V.