Related papers: Leptonic Pion Decay And Physics Beyond The Electro…

We consider a process $K_{L e5} ( K_{L} \rightarrow \pi^{0} \pi^{0} \pi^{\pm} e^{\mp} \nu )$ as a standard model background to the experiment $K_{L} \rightarrow \pi^{0} \mu^{\pm} e^{\mp}$, which seeks for possible violation of lepton family…

Pion beta decay, $\pi^+\to \pi^0 e^+\nu(\gamma)$, provides a theoretically clean $\pm 0.3\%$ determination of the CKM matrix element $V_{\text{ud}}$. That value falls short of super-allowed nuclear beta decays where an order of magnitude…

The CP conserved non leptonic $K\to \pi \pi \pi$ decays are discussed within the chiral quark model, including chiral perturbation theory corrections. All amplitudes are parameterized in terms of quark and gluon condensate and the…

Pionic beta decay \pi^+ to \pi^0 e^+ \nu_e is analyzed in chiral perturbation theory with virtual photons and leptons. All electromagnetic corrections up to order e^2 p^2 are taken into account. Theoretical results are confronted with…

Two-point functions related to the pion weak decay constant $f_\pi$ are calculated from the generating functional of chiral perturbation theory in the mean field approximation and the heavy-baryon limit. The aim is to demonstrate that…

We analyze the sensitivity of hadronic tau decays to non-standard interactions within the model-independent framework of the Standard Model Effective Field Theory (SMEFT). Both exclusive and inclusive decays are studied, using the latest…

We analyse the semileptonic decay D+ -> K- pi+ l+ nu(l) using an effective Lagrangian developed previously to describe the decays D -> P l nu(l) and D -> V l nu(l). Light vector mesons are included in the model which combines the heavy…

An enhanced electroweak penguin amplitude due to the presence of unknown new physics can explain the discrepancies found between theory and experiment in the B -> pi K decays, in particular in A_CP(B^- -> pi^0 K^-) - A_CP(\bar{B}^0 -> pi^+…

We consider the bremsstrahlung and model-dependent contributions to the radiative decay $\tau^- \to \pi^-\pi^0\nu_{\tau}\gamma$ in the context of a meson dominance model. We focus on several observables related to this decay, including the…

The PIBETA collaboration has used a non-magnetic pure CsI calorimeter operating at the Paul Scherrer Institute to collect the world's largest sample of rare pion and muon decays. We have extracted the absolute pi+ -> pi0 e+ nu decay…

Measurements of the combined branching ratios for $B^\pm \to \pi^\pm K$ and $B_d \to \pi^\mp K^\pm$ allow interesting constraints on the CKM angle $\gamma$, the ratio $r \equiv |T'|/|P'|$ of the current-current and penguin operator…

Using a large acceptance calorimeter and a stopped pion beam we have made a precise measurement of the rare Pi+ -> Pi0 e+ Nu,(pi_beta) decay branching ratio. We have evaluated the branching ratio by normalizing the number of observed…

The contributions of the chiral gauge leptoquarks $V^{L,R}$ induced by the chiral four color quark-lepton symmetry to the branching ratios of $ K_L^0, B^0, B_s \to l_1 \, l_2 $ decays are calculated and analysed using the general…

We study the $\tau^- \to \nu_{\tau} \pi^{-}\pi^{0}\ell^{+}\ell^{-}$ ($\ell=e,\,\mu$) decays, which are $O(\alpha^2)$-suppressed with respect to the dominant di-pion tau decay channel. Both the inner-bremsstrahlung and the structure- (and…

Based on the latest experimental data of $B \to \pi\pi$ and $\pi K$ modes, a model-independent analytical analysis is presented. The CP-averaged branching ratio difference $\Delta R = R_c - R_n$ in $B\to \pi K$ decays with $R_c =…

The non-leptonic $D^0\to K^- K^+$ and $D^0\to \pi^-\pi^+$ decays are powerful probes of the Standard Model and are related to each other through the $U$-spin symmetry of the strong interaction. Using lattice QCD inputs we calculate the…

We evaluate the non leptonic decays $B \to D^* \pi \pi$ and $B \to D^* \rho \pi$ in the limit of infinitely heavy quarks, assuming the dominance of intermediate positive parity charmed resonances. We find that the branching ratios are of…

We analyze the contributions to rare kaon decays mediated by flavor-changing Z-penguin diagrams in a generic low-energy supersymmetric extension of the Standard Model. In order to perform a model-independent analysis we expand the squark…

The decays $\rho^0\to 2\pi^+2\pi^-$ and $\rho^0\to 2\pi^0\pi^+\pi^-$ are studied using various effective Lagrangians for $\pi$ and $\rho$ (and in some cases $a_1$) mesons, all of which respect the approximate chiral symmetry of the strong…

We report improved measurements of branching fractions for B -> K pi and B -> pi pi decays based on a data sample of 449 million B Bbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e^+e^- collider. We…