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.

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 $\rho \to \pi \pi$, and the $\rho \to \pi \pi \gamma$ decays are taken into account. It is found that the width difference $\Delta {\Gamma }_{\rho }$ is very sensitive to the isospin breaking in the $\rho$ meson mass, $\Delta m_{\rho }$. This result can be useful to test the correlations observed between the values of these parameters extracted from experimental data.

In this article, the long-distance correction to the total decay width of the ${\tau }^{\pm }\to K^0{\pi }^{\pm }\nu$ decay is calculated in a model-independent approach, in which a discrimination of photons in the bremmstrahlung process is assumed. This correction is completely free of ultraviolet and infrared singularities, and, moreover, it satisfies electromagnetic gauge invariance. The result of this work can be applied on the tau decays: ${\tau }^{\pm }\to {\pi }^{\pm }{\pi }^0\nu$, $K^{\pm }{\pi }^0\nu$. DOI: http://dx.doi.org/10.1103/PhysRevD.88.073009 © 2013 American Physical Society

Current predictions for the ratio of $\varphi \to K^{+}{K}^{-}/K_L{K}_S$ decay rates exceed the corresponding experimental value in about 5 standard deviations. By far, the dominant sources of isospin breaking to this ratio are the phase-space (52%) and the electromagnetic radiative (4.3%, computed within scalar QED) corrections. Here we estimate the effects of the electromagnetic structure of kaons and other model-dependent contributions into the radiative corrections.