Related papers: Epsilon'/Epsilon in the Chiral Limit using Large N…
I calculate the leading logarithmic contributions up to two-loop order of the octet part of the K -> pi pi amplitude. This sector of the weak chiral Lagrangian is believed to be the main source of the enhancement of the I=0 relative to the…
We present a status report on our study of long-distance contributions to the decay amplitudes A(K^0 --> pi pi, I) in the framework of the 1/N expansion. We argue that a modified prescription for the identification of meson momenta in the…
The theoretical status of direct CP violation $\epsilon'/\epsilon$ is briefly reviewed. Special attention is paid to the recent new consistent predictions for both the ratio $\epsilon'/\epsilon$ and the $\Delta I = 1/2$ rule within the…
The $\Delta I=1/2$ rule and direct CP violation $\epsilon'/\epsilon$ in kaon decays are studied within the framework of the effective Hamiltonian approach in conjunction with generalized factorization for hadronic matrix elements.
A complete analysis of isospin breaking in $K\to 2\pi$ 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…
Relations between nucleon, $\Delta$ and nucleon-$\Delta$ electromagnetic properties associated with chiral physics which have been derived in a pure large-$N_c$ limit are greatly modified in a combined large $N_c$ and chiral limits; the…
I give a detailed introduction into the theoretical formalism for epsilon'/epsilon, which measures direct CP-violation in K -> pi pi decays. The current status of hadronic matrix elements and the strange quark mass is discussed. Several…
I discuss the estimate of the CP-violating ratio eps'/eps by stressing the role played by the chiral quark model in predicting the experiment and in showing that the same dynamical mechanism at work in the Delta I=1/2 rule also explains the…
We report on recent advances at understanding the $\Delta I= 1/2$ rule for kaons. We get reasonable matching between short-- and long--distances for scales between between 0.6 and 1.0 GeV and reproduce the $\Delta I=1/2$ rule huge…
On the basis of a next-to-leading-order calculation in chiral perturbation theory, the first complete analysis of isospin breaking for direct CP violation in K^0 -> 2 pi decays is performed. We find a destructive interference between three…
In the limit of large $N_c$ we first consider the $N_c$ ordering of the various parity violating $\pi, N, \Delta$ couplings. Then we derive the relations among these couplings and consistency relations from the stability of these couplings…
We discuss the theoretical and experimental status of the CP violating ratio eps'/eps. We revise our 1997 standard-model estimate-based on hadronic matrix elements computed in the chiral quark model up to O(p^4) in the chiral expansion-by…
I shortly review the present status of the theoretical estimates of eps'/eps. I consider a few aspects of the theoretical calculations which may be relevant in understanding the present experimental results. I discuss the role of higher…
The CP violating parameter epsilon'/epsilon is computed using the low-energy dynamics of a chiral theory supplemented by vector resonances. The divergent contributions coming from strong pi-pi scattering are tamed by vector-meson exchange…
It is shown that the implementation of the Large--$N_c$ approximation helps to get insight into the structure of, in principle, any QCD-like theory. As an example, we will compute the NLO corrections to $L_{10}$ in the chiral limit with a…
We calculate the hadronic matrix elements to $O(p^4)$ in the chiral expansion for the ($\Delta S =1$) $K^0 \to 2 \pi$ decays and the ($\Delta S=2$) $\bar K^0$-$K^0$ oscillation. This is done within the framework of the chiral quark model.…
Recent work by J.~Prades and myself on $K\to\pi\pi$ is described. The first part describes our method to connect in a systematic fashion the short-distance evolution with long-distance matrix-element calculations taking the scheme…
We analyze the theoretical implications of the new KTeV measurement of direct CP-violation in K->pi pi decays. The result is found consistent with the Standard Model for low values of the strange quark mass m_s. If the hadronic parameters…
We have combined a new systematic calculation of mesonic matrix elements at O(p^6) from an effective chiral lagrangian approach with Wilson coefficients taken from paper by G.Buchalla et al. Rev.Mod.Phys. 68 (1996) 1125, derived in the…
Strong isospin-breaking (IB) effects in CP-even and CP-odd K-->pi pi decays are computed to next-to-leading order (NLO) in the chiral expansion. The impact of these corrections on the magnitude of the Delta I=1/2 Rule and on the size of the…