Measurement of the CP-violating phase phi(s) in the B-s(0) -> J/psi phi(1020) -> mu(+)mu-K+K- channel in proton-proton collisions at root s=13 TeV

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Abstract

The $CP$-violating weak phase $\phi_\mathrm{; ; s}; ;$ and the decay width difference $\Delta\Gamma_\mathrm{; ; s}; ;$ between the light and heavy B$^0_\mathrm{; ; s}; ;$ mass eigenstates are measured with the CMS detector at the LHC in a sample of 48 500 reconstructed B$^0_\mathrm{; ; s}; ;$ $\to$ J$/\psi\, \phi$(1020) $\to$ $\mu^+\mu^-$K$^+$K$^-$ events. The measurement is based on a data sample corresponding to an integrated luminosity of 96.4 fb$^{; ; -1}; ;$, collected in proton-proton collisions at $\sqrt{; ; s}; ; =$ 13 TeV in 2017-2018. To extract the values of $\phi_\mathrm{; ; s}; ;$ and $\Delta\Gamma_\mathrm{; ; s}; ;$, a time-dependent and flavor-tagged angular analysis of the $\mu^+\mu^-$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 $\phi_\mathrm{; ; s}; ; = -$11 $\pm$ 50 (stat) $\pm$ 10 (syst) mrad and $\Delta\Gamma_\mathrm{; ; s}; ; =$ 0.114 $\pm$ 0.014 (stat) $\pm$ 0.007 (syst) ps$^{; ; -1}; ;$, in agreement with the standard model predictions. When combined with the previous CMS measurement at $\sqrt{; ; s}; ; =$ 8 TeV, the following values are obtained: $\phi_\mathrm{; ; s}; ; = -$21 $\pm$ 44 (stat) $\pm$ 10 (syst) mrad, $\Delta\Gamma_\mathrm{; ; s}; ; =$ 0.1032 $\pm$ 0.0095 (stat) $\pm$ 0.0048 (syst) ps$^{; ; -1}; ;$, a significant improvement over the 8 TeV result.

Item Type: Article High energy physics ; Experimental particle physics ; LHC ; CMS ; Hadron-Hadron scattering (experiments) ; Higgs physics ; p p: colliding beams ; Higgs particle: pair production ; bottom: 2 ; p p: scattering ; Higgs particle: coupling ; Higgs particle: hadroproduction ; Higgs particle: decay modes ; bottom: pair production ; photon: pair production ; top: pair production ; coupling: Yukawa ; coupling constant: upper limit ; vector boson: fusion ; mass spectrum: two-photon ; Standard model NATURAL SCIENCES > Physics Division of Experimental Physics Dinko Ferenček 06 Apr 2022 11:28 http://fulir.irb.hr/id/eprint/7201 10.1016/j.physletb.2021.136188