Related papers: The Delta I=1/2 rule and epsilon'/epsilon
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 perform a study of matrix elements relevant for the Delta I=1/2 rule and the direct CP-violation parameter epsilon-prime from first principles by computer simulation in Lattice QCD. We use staggered (Kogut-Susskind) fermions, and employ…
We study the $\Delta I = 1/2$ rule for kaon decays and the $B_K$ parameter for $K^0 - {\bar K}^0$ mixing in a dual 5-dimensional holographic QCD model. We perform, in the chiral limit, computations of the relevant four-point current-current…
I shortly review the present status of the theoretical calculations of eps'/eps and the comparison with the present experimental results. I discuss the role of higher order chiral corrections and in general of non-factorizable contributions…
We review different definitions of the $\epsilon'$ parameter describing direct CP violation in neutral kaon decays, which was precisely measured in recent experiments, and point out the inconsistency of some of them due to a CPT constraint.…
The $|\Delta I|=1/2$ rule in non-leptonic decays of hyperons can be naturally understood by postulating a priori mixed physical hadrons, along with the isospin invariance of the responsible transition operator. It is shown that this…
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…
Data indicate that $\Delta I=1/2$ transitions account for 4.5-4.7% of both CP conserving and CP violating $K \to 2\pi$ decays, as well as CP conserving radiative $K \to \pi\pi\gamma$ processes. Observed $K \to \pi\pi\gamma/\pi\pi$ branching…
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…
We present new results for the matrix elements of the Q_6 and Q_4 penguin operators, evaluated in a large-Nc approach which incorporates important O(N_c^2\frac{n_f}{N_c}) unfactorized contributions. Our approach shows analytic matching…
CKM-unitarity, direct and indirect CP-violation and the \Delta I=1/2 rule in full lattice QCD are the focus of this talk. To this end I will discuss and compare recent lattice results for leptonic, semi-leptonic and non-leptonic decays of…
A strong violation of the $\displaystyle{\Delta I = {1\over 2}} $ rule has experimentally been found in the $\displaystyle{D \to \pi\pi}$ decays [1]. In this letter we will show that the order of magnitude of this violation can be…
The present theoretical status of the parameter for direct CP violation epsilon'/epsilon in the Standard Model is reviewed and compared with most recent experimental measurements of the same quantity. After collecting the basic expressions…
We review the information on the CKM matrix elements, unitarity triangle and CP-violating phases $\alpha, \beta$ and $\gamma$ in the standard model which will be measured in the forthcoming experiments at B factories, HERA-B and hadron…
We calculate all the branching ratios and direct CP violations of $B \to PV$ decays in a most general two-Higgs-doublet model with spontaneous CP violation. As the model has rich CP-violating sources, it is shown that the new physics…
The |\Delta I|=1/2 rule in non-leptonic decays of hyperons can be naturally understood by postulating a priori mixed physical hadrons, along with the isospin invariance of the responsible transition operator. It is shown that this operator…
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 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…
A consistent census of penguins in the Delta I = 1/2 rule is taken from the eta0 pole contribution to the radiative KL to gamma gamma, KS to pi0 gamma gamma and K+ to pi+ gamma gamma decay modes. We briefly comment on its impact for KL to…
In this short review, I present the recent lattice computations of kaon weak matrix elements relevant to $K \to \pi\pi$ decays and neutral kaon mixing. These matrix elements are key to the theoretical determination of the CP violation…