Related papers: Improved estimates of rare K decay matrix-elements…

Partially quenched theories are theories in which the valence- and sea-quark masses are different. In this paper we calculate the nonanalytic one-loop corrections of some physical quantities: the chiral condensate, weak decay constants,…

We examine the rates for the exclusive decays $B\to K^{(*)}\ell^+\ell^-$. We use the scaling predictions of the heavy quark effective theory to extract the necessary form factors from fits to various combinations of data. These data include…

In this talk I discuss the theoretical issues associated with lattice calculations of isospin breaking corrections to hadronic matrix elements. I concentrate on the calculation of QCD isospin breaking effects for the Kl2 and Kl3 decay rates…

We calculate the $O(p^6)$ corrections to the anomalous form factors appearing in $\pi^+$, $K^+ \to e^+ \nu \gamma,\ \mu^+\nu\gamma$ and $K_{l4}$ decays in Chiral Perturbation Theory. The relevant dimension $6$ terms of the lagrangian are…

We present the scattering lengths for the $\pi K$ processes in the three flavour Chiral Perturbation Theory (ChPT) framework at next-to-next-to-leading order (NNLO). The calculation has been performed analytically but we only include…

We summarize the theoretical virtues of the rare K -> pi nu nu-bar decays and emphasize the unique role of KL -> pi0 nu nu-bar in probing the nature of physics beyond the Standard Model, in particular concerning possible new sources of CP…

The form factors for the $K_{\ell 3}$ semileptonic decay are computed to order $O(p^4)$ in generalized chiral perturbation theory. The main difference with the standard $O(p^4)$ expressions consists in contributions quadratic in quark…

A brief survey of applications of chiral perturbation theory to both semileptonic and nonleptonic kaon decays is presented. Special emphasis is given to recent theoretical advances related to semileptonic decays, in particular pion pion…

Decays $K^{+} \rightarrow \mu^{+}\nu_{\mu} \nu \bar \nu$ and $K^{+}\rightarrow e^{+}\nu_{e} \nu \bar \nu$ are examined to the leading order in momenta in the framework of Chiral Perturbation Theory. Predictions of the Standard Model for the…

We calculate the two form-factors for the four Kaon to pion transitions via a vector current to order $p^6$ in Chiral Perturbation Theory to first order in isospin breaking via the quark masses. In addition we derive relations between these…

Rare weak decays of $\eta^\prime\to K\pi$ have been investigated in the framework of the $U(3)$ chiral perturbation theory at the leading order. Our study shows that the branching ratio ${\cal B}(\eta^\prime\to K\pi)$ is of the order of…

In the heavy-quark limit, the hadronic matrix elements entering nonleptonic $B$-meson decays into two light mesons can be calculated from first principles including ``nonfactorizable'' strong-interaction corrections. The $B\to\pi K,\pi\pi$…

We study nonperturbative corrections to the inclusive rare decay B -> X_s l^+ l^- by performing an operator product expansion (OPE) to O(1/m_b^3). The values of the matrix elements entering at this order are unknown and introduce…

The decays $K_L \to \gamma\gamma$ and $K_L \to \ell^+ \ell^- \gamma$ are studied at the leading order $p^6$ in Chiral Perturbation Theory. One-loop contributions stemming from the odd intrinsic parity $|\Delta S| = 1$ effective Lagrangian…

We investigate the rare decay processes of the K mesons, K_{L,S} -> \pi^0 \nu \bar{\nu} and K^{+} -> \pi^+ \nu \bar{\nu} in LR model with lepton family number being well conserved. In these processes, scalar operators…

I discuss recent developments on non-leptonic and radiative kaon decays mainly related to direct CP-violation within the combined ChPT and 1/N_c expansion approaches. In particular, I review the status of K -> pi pi, epsilon_K', direct…

The dominant MSSM effects in the rare K decays, K+ --> pi+ nu nu bar, KL --> pi0 nu nu bar, KL --> pi0 e+ e- and KL --> pi0 mu+ mu-, are discussed both within and without the minimal flavor violation hypothesis, at moderate and large…

The decays $K \to \pi l^{+} l^{-}$, $K \to \pi \gamma \gamma $ and $K \to \pi \nu {\bar \nu}$ are investigated using the higher order terms of the chiral perturbation theory. The counterterms induced by strong, weak and electromagnetic…

We present new results on the related rare KL decay modes KL -> pi+ pi- gamma and KL -> pi+ pi- e+ e-. KTeV has performed the first direct measurement of the form factor for the "direct emission" component of KL -> pi+ pi- gamma decays, a…

We use vector meson dominance to calculate non-perturbative contributions to the branching ratio of the rare decay $K^\pm \to \pi^\pm \nu\bar \nu$ stemming from matrix elements involving up-quark loops. The importance of this observable as…