Full angular spectrum analysis of tensor current contribution to $A_{cp}(τ\rightarrow K_{s} πν_τ)$

Abstract

Babar collaboration has reported an intriguing opposite sign in the integrated decay rate asymmetry $A_{cp}(τ\rightarrow K_{s} πν_τ)$ than that of SM prediction from the known $K^{0}$ - $\bar{K^{0}}$ mixing. Babar's result deviate from the SM prediction by about 2.7$σ$. If the result stands with higher precision in the future experiments, the observed sign anomaly in the $A_{cp}(τ\rightarrow K_{s} πν_τ)$ can most likely come only from a NP. In this work we present a full angular spectrum analysis on the contribution to $A_{cp}(τ\rightarrow K_{s} πν_τ)$ coming from the tensorial term. Assuming the real part of the NP tensorial coupling is negligible compare to its imaginary part and with $A_{cp}(τ\rightarrow K_{s} πν_τ)$ and $Br(τ\rightarrow K_{s} πν_τ)$ as data points to fit the imaginary part of the NP coupling, we have been able to fit the result within 1$σ$ of the experimental values.