Measurement of the &lt;em&gt;CP&lt;/em&gt;-violating phase &lt;em&gt;ϕ&lt;/em&gt;&lt;sub&gt;s&lt;/sub&gt; in the B&lt;sub&gt;s&lt;/sub&gt;&lt;sup&gt;0&lt;/sup&gt; → J/ψϕ(1020) → μ&lt;sup&gt;+&lt;/sup&gt;μ&lt;sup&gt;-&lt;/sup&gt;K&lt;sup&gt;+&lt;/sup&gt;K&lt;sup&gt;-&lt;/sup&gt; channel in proton-proton collisions at √&lt;em&gt;s&lt;/em&gt; = 13T eV

Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Dragicevic, M.; Erö, J.; Escalante Del Valle, A.; Frühwirth, R.; Jeitler, M.; Caminada, L.; Erdmann, W.; Horisberger, R.; Ingram, Q.; Kaestli, H.C.; Kotlinski, D.; Langenegger, U.; Rohe, T.; Vetens, W.

doi:10.1016/j.physletb.2021.136188

Measurement of the CP-violating phase ϕ_s in the B_s⁰ → J/ψϕ(1020) → μ⁺μ^-K⁺K^- channel in proton-proton collisions at √s = 13T eV

Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Bergauer T, Dragicevic M, Erö J, Escalante Del Valle A, Frühwirth R, Jeitler M, Caminada L, Erdmann W, Horisberger R, Ingram Q, Kaestli HC, Kotlinski D, Langenegger U, Rohe T, Vetens W, et al.

Citation

Sirunyan, A. M., Tumasyan, A., Adam, W., Ambrogi, F., Bergauer, T., Dragicevic, M., … Vetens, W. (2021). Measurement of the CP-violating phase ϕ_s in the B_s⁰ → J/ψϕ(1020) → μ⁺μ^-K⁺K^- channel in proton-proton collisions at √s = 13T eV. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 816, 136188 (27 pp.). https://doi.org/10.1016/j.physletb.2021.136188

Persistent URL https://www.dora.lib4ri.ch/psi/islandora/object/psi:37281

The CP-violating weak phase ϕ_s and the decay width difference ΔΓ_s between the light and heavy B_s⁰ mass eigenstates are measured with the CMS detector at the LHC in a sample of 48500 reconstructed B_s⁰ → J/ψϕ(1020) → μ⁺μ^-K⁺K^- events. The measurement is based on a data sample corresponding to an integrated luminosity of 96.4fb^-1, collected in proton-proton collisions at √s = 13TeV in 2017–2018. To extract the values of ϕ_s and ΔΓ_s, a time-dependent and flavor-tagged angular analysis of the μ⁺μ^-K⁺K- final state is performed. The analysis employs a dedicated tagging trigger and a novel opposite-side muon flavor tagger based on machine learning techniques. The measurement yields ϕ_s = -11±50 (stat) ± 10 (syst)mrad and ΔΓ_s = 0.114±0.014 (stat)±0.007 (syst)ps^-1, in agreement with the standard model predictions. When combined with the previous CMS measurement at √s = 8 TeV, the following values are obtained: ϕ_s = -21 ± 44 (stat) ± 10 (syst) mrad, ΔΓ_s = 0.1032 ± 0.0095 (stat)±0.0048 (syst)ps^-1, a significant improvement over the 8 TeV result.