Related papers: Epsilon'/Epsilon in the Chiral Limit using Large N…
The $K\to\pi\pi$ system is analyzed in the chiral limit within the Standard Model. We discuss how to connect the short-distance running in the $|\Delta S|=1$ case to the matrix-elements calculated in a low-energy approximation in a…
We report on a calculation of $\epsilon_K'/\epsilon_K$ at next-to-leading in the $1/N_c$ expansion and to lowest order in Chiral Perturbation Theory. We discuss the short-distance matching, the scale and scheme dependence as well as the…
We present a new analysis of the ratio epsilon'/epsilon which measures the direct CP violation in K\to\pi\pi decays. We use the 1/N_c expansion within the framework of the effective chiral lagrangian for pseudoscalar mesons. From general…
Recent work by J.Prades and myself on $K\to\pi\pi$ is described. The method we use to consistently connect long and short distances is described and numerical results for the $\Delta I=1/2$ rule and on $B_6$, the parameter relevant for the…
The long-distance contributions to $K\to 2\pi$ amplitudes can be pinned down, using well established Chiral Perturbation Theory techniques. The strong S--wave rescattering of the two final pions generates sizeable chiral loop corrections,…
I : Chiral Perturbation Theory is introduced and its applications to semileptonic and nonleptonic kaon decays are discussed. II: The method of large $N_c$ is used to calculate $K\to\pi\pi$ nonleptonic matrix elements, in particular the…
We present a new analysis of the ratio \epsilon'/\epsilon which measures the direct CP violation in K\to\pi\pi decays. We use the 1/N_c expansion within the framework of the effective chiral lagrangian for pseudoscalar mesons. The 1/N_c…
I shortly review the present status of the theoretical calculations of epsilon'/epsilon and the comparison with the present experimental results. I discuss the role of higher order chiral corrections and in general of non-factorizable…
I discuss the role of the Delta I = 1/2 selection rule in K -> pi pi decays for the theoretical calculations of eps'/eps. Lacking reliable ``first principle'' calculations, phenomenological approaches may help in understanding correlations…
We analyze long-distance contributions to the K --> pi pi amplitudes relevant for the Delta I = 1/2 selection rule in the framework of the 1/N_c expansion. We use a modified prescription for the identification of meson momenta in the chiral…
We present a new calculation of long-distance contributions to the K --> pi pi amplitudes using the 1/N_c expansion within the framework of chiral perturbation theory. Along these lines we compute the chiral loop corrections to the…
We present a recent analysis of epsilon'/epsilon in the 1/N_c expansion. We show that the 1/N_c corrections to the matrix element of Q_6 are large and positive, indicating a Delta I = 1/2 enhancement similar to the one of Q_1 and Q_2 which…
A complete analysis of isospin breaking in K to 2 pion amplitudes, including both strong and electromagnetic corrections at next-to-leading order in chiral perturbation theory, has been achieved recently.We discuss the implication of these…
We present a new analysis of the Delta I = 1/2 rule in K --> pi pi decays and the B_K parameter. We use the 1/N_c expansion within the effective chiral lagrangian for pseudoscalar mesons and compute the hadronic matrix elements at leading…
We discuss a new estimate of $\varepsilon '/\varepsilon$ in the kaon system. The present approach is based on the evaluation of the hadronic matrix elements of the \mbox{$\Delta S =1$} effective quark lagrangian by means of the chiral quark…
We present a recent analysis of epsilon'/epsilon in the 1/N_c expansion. We show that the 1/N_c corrections to the matrix element of Q_6 are large and positive, indicating a Delta I=1/2 enhancement similar to the one of Q_1 and Q_2 which…
I discuss the comparison of the current theoretical calculations of epsilon'/epsilon with the experimental data. Lacking reliable ``first principle'' calculations, phenomenological approaches may help in understanding correlations among…
We report on a calculation of epsilon'/epsilon at next-to-leading in the 1/N_c expansion and to lowest order in Chiral Perturbation Theory. We also discuss the chiral corrections to our results and give the result of including the two known…
The measurement of epsilon'/epsilon has left open several theoretical problems, the most important of which is an accurate calculation of the relevant hadronic matrix elements. Here we study the possibility of relating epsilon' to CP…
We explore the Delta-I= 1/2 rule and epsilon'/epsilon in K -> pi pi transitions using a Dyson-Schwinger equation model. Exploiting the feature that QCD penguin operators direct K^0_S transitions through 0^{++} intermediate states, we find…