The physics of K-0-(K)over-bar(0) mixing: (B)over-cap(K) and Delta M-LS in the chiral quark model

We compute the (B) over cap(K) parameter and the mass difference Delta M-LS of the K-0-(K) over bar(0) system by means of the chiral quark model. The chiral coefficients of the relevant Delta S = 2 and Delta S = 1 chiral Lagrangians are computed via quark-loop integration. We include the relevant effects of one-loop corrections in chiral perturbation theory. The final result is very sensitive to non-factorizable corrections of O(alpha(S)N) coming from gluon condensation. The size of the gluon condensate is determined by fitting the experimental value of the amplitude K+ --> pi(+)pi(0). By varying all the relevant parameters we obtain (B) over cap(K) = 0.87 +/- 0.33. We evaluate within the model the long-distance contributions to Delta M-LS induced by the double insertion of the Delta S = 1 chiral Lagrangian and study the interplay between short- and long-distance amplitudes. By varying all parameters we obtain Delta M-LS(th)/Delta M-LS(exp) = 0.76(-0.34)(+0.64). Finally, we investigate the phenomenological constraints on the Kobayashi-Maskawa parameter Im lambda(t) entering the determination of epsilon'/epsilon. (C) 1997 Elsevier Science B.V.