Prospect for measurement of CP-violating parameters of $B_s^0 \to ϕγ$ at the Tera Z factory

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Auteurs principaux: Wang, Hengyu, Cui, Hanhua, Zhu, Yongfeng, Liang, Hao, Wang, Yuexin, Zhang, Kaili, Wang, Yi, Song, Weizheng, Li, Lingfeng, Chen, Shanzhen, Ruan, Manqi
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Publié: 2025
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author Wang, Hengyu
Cui, Hanhua
Zhu, Yongfeng
Liang, Hao
Wang, Yuexin
Zhang, Kaili
Wang, Yi
Song, Weizheng
Li, Lingfeng
Chen, Shanzhen
Ruan, Manqi
author_facet Wang, Hengyu
Cui, Hanhua
Zhu, Yongfeng
Liang, Hao
Wang, Yuexin
Zhang, Kaili
Wang, Yi
Song, Weizheng
Li, Lingfeng
Chen, Shanzhen
Ruan, Manqi
contents $b \to sγ$ transition is a critical flavor-changing neutral current (FCNC) process that could be used to probe CP violation (CPV) and new physics (NP). We quantify the anticipated precision for measuring $B_s^0 \to ϕγ$ at the CEPC Z pole operation, showing that the relative statistical uncertainty could be as low as 0.16\%, improved by approximately two orders of magnitude compared to existing measurements. Additionally, we perform a time-dependent analysis of the $B_s^0 \to ϕγ$ decay, accounting for $B_s^0/\bar{B}_s^0$ mixing extract the mixing-induced and CP-violating parameters $\boldsymbol{\mathcal{A}_{ϕγ}^Δ}$, $\boldsymbol{C_{ϕγ}}$ and $\boldsymbol{S_{ϕγ}}$. Using central value from LHCb measurement as input, we evaluate the anticipated accuracy of measurements of these parameters. The projected statistical uncertainties are $σ_{A_{ϕγ}^Δ{}^{\text{stat}}} = 0.021$, $σ_C^{\text{stat}} = 0.0092$ and $σ_S^{\text{stat}} = 0.0096$, and the systematic uncertainties are $σ_{A_{ϕγ}^Δ{}^{\text{syst}}} = 0.035$, $σ_C^{\text{syst}} = 0.0027$ and $σ_S^{\text{syst}} = 0.0064$. Furthermore, the 1$σ$ sensitivity boundaries for NP in this study are found to be $\mathcal{A}_{ϕγ}^Δ< -0.05$ or $\mathcal{A}_{ϕγ}^Δ> 0.15$, $\mathcal{C}_{ϕγ} < -0.02$ or $\mathcal{C}_{ϕγ} > 0.04$, and $\mathcal{S}_{ϕγ} < -0.04$ or $\mathcal{S}_{ϕγ} > 0.04$. We also conduct a relevant detector optimization study by establishing the correlation between the anticipated precision and the intrinsic resolution of the ECAL, as well as the performance of the PID system.
format Preprint
id arxiv_https___arxiv_org_abs_2512_23992
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Prospect for measurement of CP-violating parameters of $B_s^0 \to ϕγ$ at the Tera Z factory
Wang, Hengyu
Cui, Hanhua
Zhu, Yongfeng
Liang, Hao
Wang, Yuexin
Zhang, Kaili
Wang, Yi
Song, Weizheng
Li, Lingfeng
Chen, Shanzhen
Ruan, Manqi
High Energy Physics - Experiment
$b \to sγ$ transition is a critical flavor-changing neutral current (FCNC) process that could be used to probe CP violation (CPV) and new physics (NP). We quantify the anticipated precision for measuring $B_s^0 \to ϕγ$ at the CEPC Z pole operation, showing that the relative statistical uncertainty could be as low as 0.16\%, improved by approximately two orders of magnitude compared to existing measurements. Additionally, we perform a time-dependent analysis of the $B_s^0 \to ϕγ$ decay, accounting for $B_s^0/\bar{B}_s^0$ mixing extract the mixing-induced and CP-violating parameters $\boldsymbol{\mathcal{A}_{ϕγ}^Δ}$, $\boldsymbol{C_{ϕγ}}$ and $\boldsymbol{S_{ϕγ}}$. Using central value from LHCb measurement as input, we evaluate the anticipated accuracy of measurements of these parameters. The projected statistical uncertainties are $σ_{A_{ϕγ}^Δ{}^{\text{stat}}} = 0.021$, $σ_C^{\text{stat}} = 0.0092$ and $σ_S^{\text{stat}} = 0.0096$, and the systematic uncertainties are $σ_{A_{ϕγ}^Δ{}^{\text{syst}}} = 0.035$, $σ_C^{\text{syst}} = 0.0027$ and $σ_S^{\text{syst}} = 0.0064$. Furthermore, the 1$σ$ sensitivity boundaries for NP in this study are found to be $\mathcal{A}_{ϕγ}^Δ< -0.05$ or $\mathcal{A}_{ϕγ}^Δ> 0.15$, $\mathcal{C}_{ϕγ} < -0.02$ or $\mathcal{C}_{ϕγ} > 0.04$, and $\mathcal{S}_{ϕγ} < -0.04$ or $\mathcal{S}_{ϕγ} > 0.04$. We also conduct a relevant detector optimization study by establishing the correlation between the anticipated precision and the intrinsic resolution of the ECAL, as well as the performance of the PID system.
title Prospect for measurement of CP-violating parameters of $B_s^0 \to ϕγ$ at the Tera Z factory
topic High Energy Physics - Experiment
url https://arxiv.org/abs/2512.23992