Related papers: Pion, muon decays and weak interaction symmetries
The phenomenological implications to the decay of the neutral pion from the introduction of new dark particles are discussed. We calculate the contribution to the $\pi^0$ decay width and then we extend the theory by adding dark sector…
We report the first observation of the doubly-radiative decay mode of pionic hydrogen (pi- p --> gamma gamma n) and and deuterium (pi- d --> gamma gamma X) using the RMC pair spectrometer at TRIUMF. The process is interesting in the context…
A large low-background sample of events (10300) has been collected for the rare decay of kaons in flight K+ -> pi+ e+ e- by experiment E865 at the Brookhaven AGS. The decay products were accepted by a broad band high-resolution charged…
Recent experimental data on tau decays are used to reconstruct the difference in hadronic spectral densities with vector and axial-vector quantum numbers. The saturation of Das-Mathur-Okubo and Weinberg sum rules is studied. Two methods of…
We study the radiative pion decay pi+ -> e+ nu_e gamma within nonlocal chiral quark models that include wave function renormalization. In this framework we analyze the momentum dependence of the vector form factor F_V(q^2), and the slope of…
We present a new high precision measurement of parity violation in the weak interaction, using polarized muon decay. The TWIST collaboration has measured $P_\mu^\pi \xi$, where $P_\mu^\pi$ is the polarization of the muon in pion decay and…
We calculate the radiative corrections to the decays $\tau\to M \nu_\tau$ and $\pi \to l \nu_\l$, where the meson $M$ is $M=\pi$ or $K$ and the lepton $l$ is $l = e$ or $\mu$. We perform a complete calculation, which includes internal…
Electromagnetic radiative penguin decays of the B meson were studied with the BaBar detector at SLAC's PEP-II asymmetric-energy B Factory. Branching fractions and isospin asymmetry of the decay B -> K* gamma, branching fractions of B ->…
Until present the study of the form factors associated to the vector and axial-vector components of the hadronic weak current has been carried out with a plethora of modelizations of the underlying strong interactions. While of importance…
We update our analysis of rho-omega mixing effects in the pion form factor to incorporate the recently published BaBar e^+e^- --> pi^+\pi^- cross-sections. The implications for tau-decay-based Standard Model estimates of the leading order…
Recent results and future prospects of rare kaon-decay experiments at KEK, BNL, CERN and FNAL are reviewed. Topics include lepton flavor violation, T-violating transverse muon polarization in K+{mu3}, exotic decays, K0 -> pi0 ell+ ell-, and…
We examine the radiative decays of the Lambda (1405) to octet baryons, Lambda + gamma and Sigma + gamma. In the limit of SU(3) symmetry the decay rates for these two modes are related, and we compute the leading correction to the relation…
Using a large sample of charm semileptonic decays collected by the FOCUS photoproduction experiment at Fermilab, we present evidence for a small, even spin K- \pi+ amplitude that interferes with the dominant K*0 component in the K-pi+ mu-…
Recent BABAR and Belle results on rare B decays involving photons or lepton pairs are reviewed. New preliminary limits from both experiments for B-->rho gamma and B-->omega gamma, and from BABAR for B --> K nu nu and B --> tau nu are…
The rare kaon decay K^+ --> \pi^+ \nu \bar{\nu} is considered in the framework of the models based on the SU(3)_C X SU(3)_L X U(1)_N (3 - 3 - 1) gauge group. It is shown that a lower bound of the Z' mass in the 3 - 3 - 1 model with…
We present an updated discussion of $K\ra\pi \bar{l} l$ decays in a combined framework of chiral perturbation theory and Large--$N_c$ QCD, which assumes the dominance of a minimal narrow resonance structure in the invariant mass dependence…
Fermilab experiment E791 studied weak decays of D+, D_s, and D^0 mesons produced in collisions of 500 GeV/c negative pions with Pt and C targets. The experiment collected over 200,000 fully reconstructed charm decays. Four recent results…
We studied the radiative muon decay $\mu^+ \to e^+\nu\bar{\nu}\gamma$ by using for the first time an almost fully polarized muon source. We identified a large sample (~13000) of these decays in a total sample of 1.8x10^14 positive muon…
We study the exotic muon decays with five charged tracks in the final state. First, we investigate the Standard Model rate for $\mu^+ \to 3e^+\,2e^-\,2\nu$ ($B = 4.0\times 10^{-10})$ and find that the Mu3e experiment should have tens to…
The pi+pi- atom decays -in the ground state - predominantly into two neutral pions. We present a general expression for the corresponding decay width in the framework of QCD (including photons). It contains all terms at leading and…