セミナー情報

• 日時: 10月27日（月） 15:00〜
• 講師: 遠藤 基氏 (KEK)
• 題目: New sum rule challenges flavor anomalies

概要

Measurements of $ R_{D^{(*)}}=\mathrm{BR}(B\to D^{(*)}\tau\nu)/\mathrm{BR}(B\to D^{(*)}\ell\nu) (l=e,\nu) $ have shown deviations (anomalies) from the SM predictions at more than 3 level, which may suggest contributions from physics beyond the SM. In contrast, the recent measurement of $R_{\Lambda_c}=BR(\Lambda_b\to\Lambda_c\tau\nu)/BR(\Lambda_b\to\Lambda_c\ell\nu)$ is consistent with the SM prediction. Such a situation motivates investigations into potential shortcomings in the experimental data and SM predictions. In this talk, we propose a new sum rule that provides relations between those decay rates. Starting from the heavy quark and zero-recoil limits, we outline the derivation of the sum rule. We then examine deviations from these limits for realistic hadrons. We show that the correction to the sum rule is negligible compared to current experimental uncertainties, indicating that the sum rule is useful for cross-checking experimental consistency and testing the validity of the SM predictions. We also discuss future prospects.