Estimating eps'/eps in the standard model independently of Im λ_t

Abstract

The CP-violating parameter eps'/eps is estimated in a novel way by including the explicit computation of eps in the ratio as opposed to the usual procedure of taking its value from the experiments. This approach has the advantage of being independent from the determination of the CKM parameters Im λ_t and of showing more directly the dependence on the long-distance parameters. The matrix elements are taken from the chiral quark model approach, the parameters of which have been recently determined by an updated fit of the CP-conserving amplitudes entering the ΔI=1/2 rule. By taking a normal distribution for the experimental inputs and a flat one for the theoretical uncertainties, it is found that eps '/eps = (2.5 \pm 0.9) \times 10^{-3} in agreement with the current experimental data. A more conservative estimate 0.9 x 10^{-3} < eps'/eps < 5.8 x 10^{-3} is found by considering the smallest and the largest values obtained by taking a flat distribution for all inputs.