We formulate a set of Bell's inequalities for the system of two correlated neutral kaons coming from the decay of a φ-meson, without assuming CP and CP T invariance. We show that a non-vanishing value of the phenomenological parameter ε ′ would violate such inequalities, ruling out Bell's locality.

Since the 1964 discovery of KL → π+π− [1], understanding CP violation has been a major goal of particle physics. Subsequent experiments showed that the dominant mechanism of CP violation in neutral kaons (still the only particle system in which CP violation has been observed) is a small asymmetry between K0 → K and K → K0 mixing. This asymmetry, referred to as indirect CP violation, results in ...

Strong final state interaction (FSI) effects can play a central role in the Standard Model prediction of weak K → 2π matrix elements. Here, I discuss how FSI's affect the direct CP violation parameter ε ′ /ε by solving the Omnès problem for the necessary K → 2π amplitudes. The main results of this analysis have been reported in a previous paper 1 and are further discussed in Refs. 2,3. The resu...

We discuss a new estimate of ε/ε in the kaon system. The present approach is based on the evaluation of the hadronic matrix elements of the ∆S = 1 effective quark lagrangian by means of the chiral quark model, with the inclusion of meson one-loop renormalization and NLO Wilson coefficients. The estimate here reviewed is fully consistent with the ∆I = 1/2 selection rule in K → ππ decays, which i...

We present a recent analysis of ε′/ε in the 1/Nc expansion. We show that the 1/Nc corrections to the matrix element of Q6 are large and positive, indicating a ∆I = 1/2 enhancement similar to the one of Q1 and Q2 which dominate the CP conserving amplitude. This enhances the CP ratio and can bring the standard model prediction close to the measured value for central values of the parameters. Seve...