Measurement of the CP-violating phase ϕs in the Bs 0→J/ψϕ(1020)→μ+μ−K+K− channel in proton-proton collisions at s=13TeV
Journal
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Journal Volume
816
Date Issued
2021
Abstract
The CP -violating weak phase ?s and the decay width difference ΔΓs between the light and heavy Bs 0 mass eigenstates are measured with the CMS detector at the LHC in a sample of 48500 reconstructed Bs 0→J/ψ?(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 ?s and ΔΓs, 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 ?s=?11±50(stat)±10(syst)mrad and ΔΓs=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=8TeV, the following values are obtained: ?s=?21±44(stat)±10(syst)mrad, ΔΓs=0.1032±0.0095(stat)±0.0048(syst)ps?1, a significant improvement over the 8 TeV result. ? 2021 The Author(s)
Type
journal article