Full angular spectrum analysis of tensor current contribution to $A_{cp}(\tau \rightarrow K_{s} \pi \nu_{\tau})$.

Abstract

Babar collaboration has reported an intriguing opposite sign in the integrated decay rate asymmetry $A_{cp}(\tau \rightarrow K_{s} \pi \nu_{\tau})$ 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$\sigma$. If the result stands with higher precision in the future experiments, the observed sign anomaly in the $A_{cp}(\tau \rightarrow K_{s} \pi \nu_{\tau})$ can most likely come only from a NP. In this work we present a full angular spectrum analysis on the contribution to $A_{cp}(\tau \rightarrow K_{s} \pi \nu_{\tau})$ coming from the tensorial term. Assuming the real part of the NP tensorial coupling is negligible compare to its imaginary part and with $A_{cp}(\tau \rightarrow K_{s} \pi \nu_{\tau})$ and $Br(\tau \rightarrow K_{s} \pi \nu_{\tau})$ as data points to fit the imaginary part of the NP coupling, we have been able to fit the result within 1$\sigma$ of the experimental values.