Related papers: K_L -> pi pi e e in Chiral Perturbation Theory

We report on a search of relations valid at order $p^6$ in Chiral Perturbation Theory. We have found relations between $\pi\pi$, $\pi K$ scattering, $K_{\ell4}$ decays, masses and decay constants and scalar and vector form factors. In this…

The rare decay $K^\pm\to\pi^\pm\gamma\gamma$ has been recently measured from data samples collected by the NA48/2 and NA62 experiments at CERN. These measurements are presented, including model-independent spectrum measurements and fits to…

We study the |Delta I|=3/2 amplitudes of hyperon non-leptonic decays of the form B->B'+pi in the context of chiral perturbation theory. The lowest-order predictions are determined in terms of only one unknown parameter and are consistent…

We discuss how to formulate a staggered chiral perturbation theory. This amounts to a generalization of the Lee-Sharpe Lagrangian to include more than one flavor (i.e. multiple staggered fields), which turns out to be nontrivial. One loop…

We investigate the rare radiative eta decay modes eta -> pi+ pi- gamma gamma and eta -> pi0 pi0 gamma gamma within the framework of chiral lagrangians at o(p^4) and present photon spectra for both processes.

We analyse the rare kaon decays $K_S \to \gamma\gamma$ and $K_S \to \gamma\ell^+\ell^-$ $(\ell = e \mbox{ or } \mu)$ in a dispersive framework in which the weak Hamiltonian carries momentum. Our analysis extends predictions from lowest…

We give a brief introduction to chiral perturbation theory in its various settings. We discuss some applications of recent interest including chiral extrapolations for lattice gauge theory.

The amplitude for the anomalous transitions gamma pi(+) -> pi(0) pi(+) is analyzed within Chiral Perturbation Theory including electromagnetic interactions. The presence of a t-channel one-photon exchange contribution induces sizeable e^2…

In this talk, I address some recent developments in chiral perturbation theory at unphysical and physical quark masses.

We report on results of a search for the decay mode K_L -> pi^0 gamma e^+ e^- conducted by the E162 experiment at KEK. We observed no events and set a 90% confidence level upper limit of Br(K_L -> pi^0 gamma e^+ e^-)< 7.1x10^{-7} for its…

Two different topics relevant for DA$\Phi$NE and CEBAF, respectively, are covered. First we analyze the rare radiative eta decay mode $\eta\to\pi\pi\gamma\gamma$ within the framework of chiral perturbation theory at ${\cal O}(p^4)$. We then…

We study the ratios R_{e/mu}^{(P)} = Gamma(P -> e nu [gamma])/Gamma(P -> mu nu [gamma]) (P=pi,K) in Chiral Perturbation Theory to order e^2 p^4. We complement the two-loop effective theory results with a matching calculation of the…

The combination of simple dynamics, small number of available decay channels, and extremely well controlled radiative and loop corrections, make charged pion decays a sensitive means for testing the underlying symmetries and the…

Using the full data set of the NA48/2 experiment, the decay K+- -> pi+- e+ e- gamma is observed for the first time, selecting 120 candidates with 7.3 +- 1.7 estimated background events. With K+- -> pi+- pi0D as normalisation channel, the…

We have observed the rare decay K+ --> pi+ mu+ mu- and measured the branching ratio Gamma(K+ --> pi+ mu+ mu-)/Gamma(K+ --> all) = (5.0 +/- 0.4 (stat.) +/- 0.7 (sys.) +/- 0.6 (theor.)) x 10^{-8}. We compare this result with predictions from…

A brief introduction to chiral perturbation theory, the effective field theory of quantum chromodynamics at low energies, is given.

Recent lattice studies on (semi-)leptonic kaon decays towards a precise determination of V_us are reviewed. Attention is given to recent unquenched calculations and consistency of their results with chiral perturbation theory.

We review some recent theoretical results on rare kaon decays. Particular attention is devoted to find Standard Model tests. This is theoretically easy in $K\to \pi \nu \bar{\nu}$, while a careful study of the long distance contributions is…

These lectures are an introduction to the subject of chiral effective Lagrangians of the Standard Model and their applications, mostly in the sector of non--leptonic kaon decays, with special emphasis on CP--violation. The first lecture…

We construct an effective non-relativistic quantum field theory that describes bound states of pi+ pi- pairs and their hadronic decays. We then derive a general expression for the lifetime of the ground state at next-to-leading order in…