Speaker
Description
We present the first measurement of branching fraction for a rare tau decay, $\tau^{\pm} \rightarrow \pi^{\pm} e^+ e^- \nu_\tau$, using a 562 $fb^{-1}$ dataset collected with Belle detector at the KEKB asymmetric-energy e+e- collider. The $\gamma^{*}W^{*}\pi$ vertex involved in this decay provides unique knowledge to study the dynamics of strong interactions at the energy scale of tau mass. Relevant form factors can serve as an approach to test the validity of the calculation by Resonance Chiral Theory. Meanwhile, a precise measurement of Br($\tau^{\pm} \rightarrow \pi^{\pm} e^+ e^- \nu_\tau$) also facilitates the searching for LFV modes, e.g., $\tau^{\pm} \rightarrow \mu^{\pm} e^+ e^-$, where the decay mode under consideration stands as a notable background.
