Abstract
The charged lepton flavor violation process is a clean and sensitive probe of new physics beyond the Standard Model. A sensitivity study is performed to the process \(\tau ^- \rightarrow \gamma \mu ^-\) based on a 3 \(\hbox {fb}^{-1}\) inclusive Monte Carlo sample of \(e^+e^-\) collisions at a center-of-mass energy of 4.26 or 4.6 GeV, in the framework of the BESIII software system. The 90 % confidence level upper limits on \({\mathcal{{B}}}(\tau ^- \rightarrow \gamma \mu ^-)\) are estimated assuming no signal is produced. We also obtain the sensitivity on \({\mathcal{{B}}}(\tau ^- \rightarrow \gamma \mu ^-)\) as a function of the integrated luminosity, to serve as a reference for the HIEPA being proposed in China. It is found that 6.34 \(\hbox {ab}^{-1}\) are needed to reach the current best upper limit of \(4.4\times 10^{-8}\) and about 2510 \(\hbox {ab}^{-1}\) are needed to reach a sensitivity of \(10^{-9}\) if the detector design is similar to that of BESIII.
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Notes
Charge conjugate mode is included throughout this paper, the sensitivity in this paper is for combined \(\tau ^-\rightarrow \gamma \mu ^-\) and \(\tau ^+\rightarrow \gamma \mu ^+\).
C. Li’s talk “Overview of the Detector at HIEPAF” given at “Workshop on Physics at Future High Intensity Collider at 2–7 GeV in China, 13– 16 January, 2015, Hefei, China.
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Acknowledgments
Y. B. Li thanks Profs. Jing-Zhi Zhang, Rong-Gang Ping and Mr. Lian-Jin Wu for their helpful discussions and cross checks on MUC information and generator, also thanks Mr. Hong-Rong Qi for his help on the optimization of event selection. This work was supported in part by the National Natural Science Foundation of China (11235011), the National Basic Research Program of China (2015CB856701), and CAS Center for Excellence in Particle Physics (CCEPP).
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Li, YB., Shen, CP. & Yuan, CZ. Sensitivity study of searching for \(\tau ^- \rightarrow \gamma \mu ^-\) at HIEPA. Sci. Bull. 61, 307–312 (2016). https://doi.org/10.1007/s11434-016-0997-y
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DOI: https://doi.org/10.1007/s11434-016-0997-y