G. Toledo Sanchez

Long distance radiative corrections to the decay τ- → π- π0ντ

We evaluate the model-dependent piece of O(alpha) long-distance radiative corrections to tau^- \to \pi^- \pi^0\nu_{\tau} decays by using a meson dominance model. We find that these corrections to the di-pion invariant mass spectrum are smaller than in previous calculations based on chiral perturbation theory. The corresponding correction to the photon inclusive rate is tiny (-0.15%) but it can be of relevance when new measurements reach better precision.

Gauge invariance and finite width effects in radiative two pion tau lepton decay

The contribution of the rho^{\pm} vector meson to the tau -> pi pi nu gamma decay is considered as a potential source for the determination of the magnetic dipole moment of this light vector meson. In order to keep gauge-invariance of the whole decay amplitude, a procedure similar to the fermion loop-scheme for charged gauge bosons is implemented to incorporate the finite width effects of the rho^{\pm} vector meson. The absorptive pieces of the one-loop corrections to the propagators and electromagnetic vertices of the rho^{\pm} meson and W^{\pm} gauge boson have identical forms in the limit of massless particles in the loops, suggesting this to be a universal feature of spin-one unstable particles. Model-dependent contributions to the tau -> pi pi nu gamma decay are suppressed by fixing the two-pion invariant mass distribution at the rho meson mass value. The resulting photon energy and angular distribution is relatively sensitive to the effects of the rho magnetic dipole moment.

The Width difference of rho vector mesons

We compute the difference in decay widths between charged and neutral {rho}(770) vector mesons. The isospin breaking arising from mass differences of neutral and charged {pi} and {rho} mesons, radiative corrections to {rho}{yields}{pi}{pi}, and the {rho}{yields}{pi}{pi}{gamma} decays are taken into account. It is found that the width difference {delta}{gamma}{sub {rho}} is very sensitive to the isospin breaking in the {rho} meson mass, {delta}m{sub {rho}}. This result can be useful to test the correlations observed between the values of these parameters extracted from experimental data.

Radiative two-pion decay of the tau lepton

We consider the bremsstrahlung and model-dependent contributions to the radiative decay

Model-dependent radiative corrections to τ−→π−π0ν revisited

{\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\nu}}_{\ensuremath{\tau}}\ensuremath{\gamma}

Determination of the magnetic dipole moment of the rho meson using four-pion electroproduction data

in the context of a meson dominance model. We focus on several observables related to this decay, including the branching ratio and the photon and di-pion spectra. Particular attention is paid to the sensitivity of different observables upon the effects of model-dependent contributions and of the magnetic dipole moment of the

THE ωρπ COUPLING IN THE VMD MODEL REVISITED

{\ensuremath{\rho}}^{\ensuremath{-}}(770)

Dynamical quark recombination in ultrarelativistic heavy-ion collisions and the proton-to-pion ratio

vector meson. Important numerical differences are found with respect to results obtained in the framework of chiral perturbation theory.

Further remarks on isospin breaking in charmless semileptonic B decays

The long-distance electromagnetic radiative corrections to tau- -> pi- pi0 nu are re-evaluated. A meson dominance model is used to describe the emission of real photons in this decay. Results obtained for the hadronic spectrum and the decay rate in photon inclusive reactions are compared with previous calculations based on the chiral resonance theory. Independent tests in tau -> pi pi nu gamma that can help to validate the predictions of one of the two models are briefly discussed.

DETERMINATION OF THE MAGNETIC DIPOLE MOMENT OF THE RHO MESON

We determine the magnetic dipole moment of the rho meson using preliminary data from the BaBar Collaboration for the