Abstract
A measurement of the B_{s}^{0} rightarrow J/psi phi decay parameters using 80.5, mathrm {fb^{-1}} of integrated luminosity collected with the ATLAS detector from 13 text {Te}text {V} proton–proton collisions at the LHC is presented. The measured parameters include the CP-violating phase phi _{s} , the width difference Delta Gamma _{s} between the B_{s}^{0} meson mass eigenstates and the average decay width Gamma _{s}. The values measured for the physical parameters are combined with those from 19.2, mathrm {fb^{-1}} of 7 and 8 text {Te}text {V} data, leading to the following: ϕs=-0.087±0.036(stat.)±0.021(syst.)radΔΓs=0.0657±0.0043(stat.)±0.0037(syst.)ps-1Γs=0.6703±0.0014(stat.)±0.0018(syst.)ps-1\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$\\begin{aligned} \\phi _{s}= & {} -0.087 \\pm 0.036 ~\\mathrm {(stat.)} \\pm 0.021 ~\\mathrm {(syst.)~rad} \\\\ \\Delta \\Gamma _{s}= & {} 0.0657 \\pm 0.0043 ~\\mathrm {(stat.)}\\pm 0.0037 ~\\mathrm {(syst.)~ps}^{-1} \\\\ \\Gamma _{s}= & {} 0.6703 \\pm 0.0014 ~\\mathrm {(stat.)}\\pm 0.0018 ~\\mathrm {(syst.)~ps}^{-1} \\end{aligned}$$\\end{document}Results for phi _{s} and Delta Gamma _{s} are also presented as 68% confidence level contours in the phi _{s} – Delta Gamma _{s} plane. Furthermore the transversity amplitudes and corresponding strong phases are measured. phi _{s} and Delta Gamma _{s} measurements are in agreement with the Standard Model predictions.
Highlights
CKMFitter group [2] and −2βs = −0.03700 ± 0.00104 rad according to the UTfit Collaboration [3]
The calibration data are split into subsets of approximately equal size, separated according to the estimated pile-up of the event, and separate calibrations are made for each subset
To assess the effects of mis-modelling of the Bs0 vertex χ 2/ndof in simulated data, an alternative fit is done with Monte Carlo (MC) χ 2/ndof reweighted according to data
Summary
The analysis of the time evolution of the Bs0 → J/ψφ decay provides the most precise determination of φs and s. Previous measurements of these quantities have been reported by the D0, CDF, LHCb, ATLAS and CMS Collaborations [10–17]. The analysis presented here introduces a measurement of the Bs0 → J/ψφ decay parameters using 80.5 fb−1 of the LHC proton–proton ( pp) data collected by the ATL√AS detector during 2015–2017, at a centre-of-mass energy, s, equal to 13 TeV. J. C (2021) 81:342 data collected at 7 and 8 TeV, and introduces more precise signal and background models.
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