The Physics of K0−K¯0 Mixing: BˆK and ΔMLS in the Chiral Quark Model

Abstract

We compute the BˆK parameter and the mass difference ΔMLS of the K0−K¯0 system by means of the chiral quark model. The chiral coefficients of the relevant ΔS=2 and ΔS=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(αSN) coming from gluon condensation. The size of the gluon condensate is determined by fitting the experimental value of the amplitude K+→π+π0. By varying all the relevant parameters we obtain BˆK=0.87±0.33 . We evaluate within the model the long-distance contributions to ΔMLS induced by the double insertion of the ΔS=1 chiral lagrangian and study the interplay between short- and long-distance amplitudes. By varying all parameters we obtain ΔMthLS/ΔMexpLS=0.76+0.64−0.34. Finally, we investigate the phenomenological constraints on the Kobayashi-Maskawa parameter Im λt entering the determination of ϵ′/ϵ.