Related papers: K_L to \pi^+ \pi^- e^+ e^-

An overview on chiral perturbation theory calculations of form factors is presented. The main focus is given on the form factors related to the lightest meson, pion, namely: pion decay constant, pion vector and scalar form factor, radiative…

We propose a description of the $K^+$, $K_S$ radiative decay form factors $W_+$, $W_S$ based on general properties of analyticity and unitarity. Starting from the simple consideration of the asymptotic behaviour of the two combinations…

Rare decays of K mesons are reviewed from the perspective of testing the ``ones'' and ``zeros'' of the standard model. Decays K^+ -> pi^+ nu anti-nu and K_L -> pi^0 nu anti-nu probe the one-loop effective Hamiltonian for s -> d nu anti-nu,…

We study dispersive representations of nonlocal form factors in $K^+ \to \pi^+ \ell^+ \ell^-$ and $K^+ \to \pi^+ \nu \bar{\nu}$ decays, with an aim of improving the theoretical description of the spectrum and decay rate of the neutrino…

Using 328 pb^{-1}of data collected at DAFNE corresponding to $\sim$ 1.8 million $K_L\to \pi\mu\nu$ decays, we have measured the $K_{\mu 3}$ form factor parameters. The structure of the $K-\pi$ vector-current provides information about the…

We present the ingredients necessary for the determination of physical K->pi pi decay amplitudes for Delta I=3/2 transitions, from lattice simulations at unphysical kinematics and the use of chiral perturbation theory at next-to-leading…

We consider electromagnetic corrections to the non-leptonic kaon decay, $K^+\to\pi^+\pi^0\pi^0$, due to explicit virtual photons only. The decay amplitude is calculated at one-loop level in the framework of Chiral Perturbation Theory. The…

We study the disintegration $\tau^- \to \pi^-\ell^+\ell^-\nu_\tau$, where $l$ denotes either an electron or a muon. This process requires knowledge about the $W^*\gamma^*\pi$ interaction, which is modeled using Resonance Chiral Theory.…

We calculate the form factors of the $K \to \pi l \nu$ semileptonic decays in three-flavor lattice QCD, and study their chiral behavior as a function of the momentum transfer and the Nambu-Goldstone boson masses. Chiral symmetry is exactly…

We reconsider the constraints on the form factors $W_+ (s)$ and $W_S (s)$, describing the radiative decay modes $K^+\to\pi^+ \ell^+\ell^-$ and $K_S\to\pi^0 \ell^+\ell^-$, associated with the general properties of analyticity and unitarity.…

The rare decay K_L -> pi pi e e that has recently been observed by KTeV is analyzed in chiral perturbation theory at the one-loop level.

We study the hadronic form factors of $\tau$ lepton decays $\tau \to K \pi(\eta) \nu$. We compute one loop corrections to the form factors using the chiral Lagrangian including vector mesons. The counterterms which subtract the divergence…

Hadronic matrix elements of the vector, axial-vector and tensor currents relevant for exclusive rare decays $B\to(\pi,\rho,K,K^*)\,l^+l^-$ induced by the quark transition $b\to d,s$ are analysed using dispersion formulation of the…

K^0 \to pi^- e^+ nu_e e^+ e^- decay is studied up to the next-to-leading order O^4 in chiral perturbation theory. It is found that the O^4 terms appreciably modifiy the shape of the invariant mass distribution of the leptons and the energy…

The $F$ and $G$ form-factors of $K_{\ell4}$ and the quark condensates are calculated to ${\cal O}(p^6)$ in Chiral Perturbation Theory (CHPT). Full formulas are presented as much as possible. A full refit of most of the ${\cal O}(p^4)$ CHPT…

We present the first complete lattice QCD calculation of the four structure-dependent form factors governing the rare charged kaon decay $K^- \to \ell^- \bar{\nu}_\ell \ell'^+ \ell'^-$, with fully controlled statistical and systematic…

Rare B decays to three charged kaons are analysed. The weak decay amplitudes are derived in the QCD factorization approach. The strong final state interactions between pairs of kaons are described using the kaon scalar and vector form…

The dependence of K_{S,L}->\pi^{+}\pi^{-}\gamma decay probabilities on photon polarization is calculated. The phases of terms of amplitude that arise from the pion-pion interaction are obtained by using a simple realistic model of pion-pion…

We present an updated analysis of the rare decay $K_{L}\to\pi^{0}\mu^{+}\mu^{-}$ within the Standard Model. In particular, we present the first complete calculation of the two-photon CP-conserving amplitude within Chiral Perturbation…

This paper describes the calculation of the electromagnetic form factor of the K0 meson at order p^6 of chiral perturbation theory which is the next-to-leading order correction to the well-known p^4 result achieved by Gasser and Leutwyler.…