QCD SUM-RULES AND CHIRAL-SYMMETRY BREAKING

We investigate, in the context of QCD sum rules, the role of Goldstone bosons arising from chiral symmetry breaking, especially on the need of matching the world of hadrons to that of some effective chiral quar k theory. We describe how such matching yields predictions on induced condensates which reproduce the observed value of the strong pi NN cou pling constant. Our result indicate that the observed large pi NN coup ling comes primarily from the nonperturbative induced-condensate effec t. On the other hand, the prediction on the parity-violating weak pi N N coupling, f(pi NN) similar to (3.0+/-0.5) x 10(-7) is in good agreem ent with the value (similar to 2 x 10(-7)) Obtained by Adelberger and Haxton from an overall fit to the existing data, but may appear to be slightly too large (but not yet of statistical significance) as compar ed to the most recent null experiment. Altogether, we wish to argue th at the proposal of matching onto a chirally broken effective theory sh ould enable us to treat, in a quantitative and consistent manner, the various nonleptonic strong and weak processes involving Goldstone boso ns.