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arXiv · 2406.01675

Measurement of CKM element $|V_{cb}|$ from $W$ boson decays at the future Higgs factories

Hao Liang·Lingfeng Li·Yongfeng Zhu·Xiaoyan Shen·Manqi Ruan
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Abstract

This study investigates the precision measurement of the CKM matrix element $|V_{cb}|$ through semileptonic $WW$ events at future Higgs factories, $i.e.$, FCC-ee, ILC, C$^3$, and CEPC. We use full detector simulation to generate the $WW \to \ell \nu cb$ signal events and various backgrounds at $\sqrt{s} = 240$ GeV with unpolarized beams. The relative statistical uncertainties are projected to be 0.91\% for the muon channel and 1.2\% for the electron channel, assuming a baseline integrated luminosity of 5 ab$^{-1}$. The sensitivities at other Higgs factory scenarios are also projected. Possible contributors to systematic uncertainties are discussed, with the most prominent one being the systematics of flavor-tagging and mistagging rates. Combining with $WW$ threshold runs, the relative systematic uncertainty can be further reduced.

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Hao Liang, Lingfeng Li, Yongfeng Zhu, Xiaoyan Shen, Manqi Ruan. 2024-06-03. Measurement of CKM element $|V_{cb}|$ from $W$ boson decays at the future Higgs factories. https://arxiv.org/abs/2406.01675

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