Feasibility study of $CP$ Violation in ${\tau }^{-}\to K_S{\pi }^{-}{\nu }_{\tau }$ decays at Super Tau Charm Facility

Abstract

We report a feasibility study of $CP$ violation of ${\tau }^{-}\to K_S{\pi }^{-}{\nu }_{\tau }$ decay at a Super Tau Charm Facility~(STCF).With an expected luminosity of 1~ab${}^{-1}$ collected by STCF per year at a center-of-mass energy of 4.26 GeV, the statistical sensitivity for the $CP$ violation is determined to be of order $9.7\times 10^{-4}$ by measuring the decay-rate difference between ${\tau }^{+}\to K_S{\pi }^{+}{\bar{\nu }}_{\tau }$ and ${\tau }^{-}\to K_S{\pi }^{-}{\nu }_{\tau }$. The analysis is performed using a reliable fast simulation software package, which can describe the detector responses properly and vary the responses flexibly for further optimization. Moreover, the energy-dependent efficiencies for reconstructing ${\tau }^{-}\to K_S{\pi }^{-}{\nu }_{\tau }$ are presented and the expected $CP$ sensitivity is proportional to $1/\sqrt{\mathcal{L}}$ in the energy region from 4.0 to 5.0 GeV. The sensitivity of $CP$ violation is of order $3.1\times 10^{-4}$ with 10~ab${}^{-1}$ integrated luminosity, which is equivalent to ten years data taking in this energy region at STCF.

References in corpus (9)

• Observation of $CP$ violation in charm decays
• Matching perturbative and Parton Shower corrections to Bhabha process at flavour factories
• Scalar K pi form factor and light quark masses
• Photon pair production at flavour factories with per mille accuracy
• Measurement of CP observables in B+- --> D_CP K+- decays and constraints on the CKM angle gamma
• Combined analysis of the decays ${\tau }^{-}\to K_S{\pi }^{-}{\nu }_{\tau }$ and ${\tau }^{-}\to K^{-}\eta {\nu }_{\tau }$
• Effective-field theory analysis of the ${\tau }^{-}\to (K\pi {)}^{-}{\nu }_{\tau }$ decays
• A fast simulation package for STCF detector
• Probing sensitivity to charged scalars through partial differential widths: $\tau \to K\pi \pi {\nu }_{\tau }$ decays

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• $CP$ asymmetry in the angular distributions of $\tau \to K_S\pi {\nu }_{\tau }$ decays -- II: general effective field theory analysis
• Flavor Physics at the CEPC: a General Perspective
• CP violation in two-meson Tau decays induced by heavy new physics