Long distance radiative corrections to the decayτ−→π−π0ντ

Abstract

We evaluate the model-dependent piece of O(α) long-distance radiative corrections to τ − → π − π 0 ντ 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.

Model-dependent radiative corrections to revisited

“…As it was discussed in ref. [8], the predictions of both models coincide when such diagram is excluded from our calculations. This also confirms that the axial-vector contributions, despite their very different origin in both models, are almost negligible.…”

“…A simple and useful analytical expression can be obtained for the long-distance correction factor. In almost all the interval of t, G EM (t) can be approximated very well by the polynomial function (x = t/m 2 τ ) [8]:…”

“…and its model-independent (m.i.) parts (see [5,8] for details). The model-independent correction G 0 EM (t) includes the sum of virtual corrections and m.i.…”

“…[7,8] the emission of real photons was considered in the framework of a meson dominance model. The idea behind our approach is that given the large momentum transfer released in τ decays, all intermediate states involving the production and decay of light resonances (ρ(770), ω(782), a 1 (1620)) (see Figure 3) that are allowed by their quantum numbers, must contribute.…”

“…A different approach to compute LD corrections, based on a meson dominance model, was considered in refs. [7,8]. Here we discuss the different results obtained from the two approaches and suggest how independent tests can be carried out in the corresponding radiative τ − → π − π 0 νγ to distinguish between the two models.…”