Abstract
We report a feasibility study for violation in decays at a Super Tau Charm Facility (STCF). With an expected luminosity of 1 ab collected by STCF per year at a center-of-mass energy of 4.26 GeV, the statistical sensitivity for CP violation is determined to be of order by measuring the decay-rate difference between and . 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 are presented. The expected CP sensitivity is proportional to in the energy region from 4.0 to 5.0 GeV. The sensitivity of CP violation is of order with 10 ab integrated luminosity, which is equivalent to ten years' data taking in this energy region at STCF.
Highlights
The Cabibbo-Kobayashi-Maskawa (CKM) matrix can accommodate CP violation (CPV) in a natural way with a complex phase in the quark mixing sector [1, 2]
CPV has not been observed in the lepton sector, and any significant observation would be a clear indication of physics beyond the Standard Model (SM)
With above selection criteria and optimization procedure, the number of signal events from τ − and τ + decay with generic Monte Carlo (MC) normalized to 1 ab−1 integrated luminosity are obtained by fit the KSπ invariant mass with RooFit tool, where signal can be parameterized by the function as shown in Eq (4) and background is described with simulated background
Summary
The Cabibbo-Kobayashi-Maskawa (CKM) matrix can accommodate CP violation (CPV) in a natural way with a complex phase in the quark mixing sector [1, 2]. We will discuss the specific channel τ − → KSπ−ντ and concentrate on the CPV and related New Physics (NP) searches This channel is of great importance for the measurements of form factors and extraction of |Vus| element in CKM matrix, and has rich intermediate resonances which provides an important play-ground for non-perturbative QCD study. A partial-wave analysis will certainly help to pin down this issue, which again needs more highquality data This point has been noted by Belle collaboration [47]: the future more data on the invariant mass spectrum of Ksπ combined with the angular analysis will elucidate the nature of scalar form factor and check various theoretical approaches.
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