Related papers: The Delta I=1/2 rule and epsilon'/epsilon

We present the inconsistencies which arise in quenched QCD in $\Delta I=1/2$ non-leptonic kaon decays using chiral perturbation theory (ChPT) to one loop. In particular we discuss how the lack of unitarity of the quenched theory invalidates…

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…

We review the current status of calculations of the two pion decays of the kaon using the first-principles methods of lattice gauge theory and the significant challenges that these calculations pose. While a calculation with controlled…

We present our preliminary results for the $\Delta I = 1/2$ matrix elements of $K\to\pi\pi$ decay and $\varepsilon'$, the measure of direct $CP$ violation in $K\to\pi\pi$, computed on multiple ensembles with periodic boundary conditions…

By employing recent data on non-mesonic decay of s-shell Lambda-hypernuclei we study, within the phenomenological model of Block and Dalitz, the validity of the Delta I=1/2 rule in the Lambda N--> NN process. Due to the low experimental…

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…

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…

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…

There are different approaches for the hadronic B decay calculations, recently. In this paper, we upgrade three of them, namely factorization, QCD factorization and the perturbative QCD approach based on $k_T$ factorization, by using new…

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…

We review and update our results for K-> pipi decays and K^0-\bar K^0 mixing obtained by us in the 1980s within an approach based on the dual representation of QCD as a theory of weakly interacting mesons for large N colours. In our…

We review the Standard Model predictions of CP violation in kaon decays. We present an elementary introduction to Chiral Perturbation Theory, four--quark effective hamiltonians and the relation among them. Particular attention is devoted to…

This review of CP violation focuses on the status of the subject and its likely future development through experiments in the Kaon system and with B-decays. Although present observations of CP violation are perfectly consistent with the CKM…

We devise tests for a new physics origin of the recently measured direct CP violation in singly Cabibbo suppressed D decays. The tests take the form of sum rules for the CP asymmetries in various D decays. They are based on the fact that…

The experimental value for the isospin amplitude Re(A_2) in K->pi pi decays has been successfully explained within the Standard Model, both within large N approach to QCD and by QCD lattice calculations. On the other hand in both approaches…

The problem of calculation of the enhancement factor due to the strong pion final state interaction is reexamined in the light of recent interest in understanding of the origine of the $\Delta I=1/2$ rule and calculations of the CP…

Non-leptonic kaon decays are often described through an effective chiral weak Hamiltonian, whose couplings ("low-energy constants") encode all non-perturbative QCD physics. It has recently been suggested that these low-energy constants…

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…

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…

The K to pi pi system is analyzed in the chiral limit and at NLO in 1/N_c. The Delta I = 1/2 rule is reproduced and we obtain a large value for epsilon' / epsilon.