Top quark mass measurements at the $t\bar{t}$ threshold with CEPC

• Main Authors: Li, Zhan, Sun, Xiaohu, Fang, Yaquan, Li, Gang, Xin, Shuiting, Wang, Shudong, Wang, Yiwei, Zhang, Yuan, Zhang, Hao, Liang, Zhijun
• Format: Journal Article
• Language: English
• Published: 25.07.2022
• Subjects: Physics - High Energy Physics - Experiment; Physics - High Energy Physics - Phenomenology
• DOI: 10.48550/arxiv.2207.12177

We present a study of top quark mass measurements at the $t\bar{t}$ threshold based on CEPC. A centre-of-mass energy scan near two times of the top mass is performed and the measurement precision of top quark mass, width and $\alpha_S$ are evaluated using the $t\bar{t}$ production rates. Realistic scan strategies at the threshold are discussed to maximise the sensitivity to the measurement of the top quark properties individually and simultaneously in the CEPC scenarios assuming a limited total luminosity of 100 fb$^{-1}$. With the optimal scan for individual property measurements, the top quark mass precision is expected to be 9 MeV, the top quark width precision is expected to be 26 MeV, and $\alpha_S$ can be measured at a precision of 0.00039. Taking into account the uncertainties from theory, background subtraction, beam energy and luminosity spectrum, the top quark mass can be measured at a precision of 14 MeV optimistically and 34 MeV conservatively at CEPC.