A novel machine-learning-based flavor-tagging algorithm combining same-side and opposite-side tagging is used to obtain the equivalent of 27 500 tagged B-s(0) -> J/psi phi(1020) decays from pp collisions at root s = 13 TeV, collected by the CMS experiment and corresponding to an integrated luminosity of 96.5 fb-1. A time- and flavor-dependent angular analysis of the mu(+)mu-K+K- final state, consistent with a phi(1020) -> K+K- decay, is used to measure parameters of the B-s(0) - (B) over bar (0)(s) system. The weak phase is measured to be phi(s) = - 73 +/- 22(stat) +/- 10(syst) mrad, which, combined with the root s = 8 TeV CMS result, gives phi(s) = - 75 +/- 23 mrad. This value differs from zero by 3.2 standard deviations, providing the first evidence for mixing-induced CP violation in B-s(0) -> J/psi phi(1020) decays. All measured physics parameters are found to agree with standard model predictions where available.

Hayrapetyan, A., Tumasyan, A., Adam, W., Andrejkovic, J.W., Benato, L., Bergauer, T., et al. (2026). First Evidence for Mixing-Induced CP Violation in Bs0 → J/ψφ(1020) Decays in pp Collisions at √s=13 TeV. PHYSICAL REVIEW LETTERS, 136(18) [10.1103/ctqx-vxrj].

First Evidence for Mixing-Induced CP Violation in Bs0 → J/ψφ(1020) Decays in pp Collisions at √s=13 TeV

Ciocci, M. A.;Turini, N.;
2026-01-01

Abstract

A novel machine-learning-based flavor-tagging algorithm combining same-side and opposite-side tagging is used to obtain the equivalent of 27 500 tagged B-s(0) -> J/psi phi(1020) decays from pp collisions at root s = 13 TeV, collected by the CMS experiment and corresponding to an integrated luminosity of 96.5 fb-1. A time- and flavor-dependent angular analysis of the mu(+)mu-K+K- final state, consistent with a phi(1020) -> K+K- decay, is used to measure parameters of the B-s(0) - (B) over bar (0)(s) system. The weak phase is measured to be phi(s) = - 73 +/- 22(stat) +/- 10(syst) mrad, which, combined with the root s = 8 TeV CMS result, gives phi(s) = - 75 +/- 23 mrad. This value differs from zero by 3.2 standard deviations, providing the first evidence for mixing-induced CP violation in B-s(0) -> J/psi phi(1020) decays. All measured physics parameters are found to agree with standard model predictions where available.
2026
Hayrapetyan, A., Tumasyan, A., Adam, W., Andrejkovic, J.W., Benato, L., Bergauer, T., et al. (2026). First Evidence for Mixing-Induced CP Violation in Bs0 → J/ψφ(1020) Decays in pp Collisions at √s=13 TeV. PHYSICAL REVIEW LETTERS, 136(18) [10.1103/ctqx-vxrj].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/1324438