Measurement of time-dependent CP violation in B0(s)->J/Psi K-short decays with the CMS experiment

About

Time-dependent CP-violation measurements in neutral B-meson decays provide stringent tests of the Cabibbo–Kobayashi–Maskawa description of flavour physics and indirect sensitivity to physics beyond the Standard Model. The decay of neutral B0 mesons to J/Psi K-short mesons offers theoretically clean access to the CKM angle beta, while the SU(3)-related decay of Bs mesons to the same final state provides complementary sensitivity to beta_s and to subleading penguin contributions that affect the interpretation of precision measurements.

This seminar presents a CMS measurement of CP violation in both decay modes using the full Run 3 dataset collected between 2022 and 2025. Approximately 1.4 million B0 and 16 thousand Bs signal decays are reconstructed. Their time evolution is studied using dedicated flavour-tagging algorithms based on state-of-the-art Transformer architectures to determine the production flavour of each candidate. The resulting measurements of mixing-induced and direct CP violation are consistent with standard model predictions, reach competitive precision in the B0 channel, and substantially improve the experimental knowledge of the Bs decay.

Coffee will be served at 10h30

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