Abstract
The CP -violating weak phase ϕs and the decay width difference ΔΓs between the light and heavy Bs0 mass eigenstates are measured with the CMS detector at the LHC in a sample of 48500reconstructed Bs0→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 ϕs 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 ϕs=−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: ϕs=−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.
Highlights
Precision tests of the standard model (SM) of particle physics have become increasingly important, since no direct evidence for new physics has been found so far at the 0 s mesons present important opportunities to probe the consistency of the SM
In this Letter, a new measurement of the C P -violating weak phase φs and the decay width difference s between the light
The second level, known as the high-level trigger (HLT), consists of a farm of processors running a version of the full event reconstruction software optimized for fast processing, and reduces the event rate to around 1 kHz before data storage
Summary
Precision tests of the standard model (SM) of particle physics have become increasingly important, since no direct evidence for new physics has been found so far at the CERN. In this Letter, a new measurement of the C P -violating weak phase φs and the decay width difference s between the light A time-dependent angular analysis can be performed by measuring the decay angles of the final-state particles and the proper decay length of the reconstructed. 0 s candidate, which is equal to the proper decay time t multiplied by the speed of light, and referred to as ct in what follows Is the decay amplitude meson to the final state f , and the parameters p and q relate the mass and flavor eigenstates through p|B0s q|B. q|B0s [24]. Equation (1) represents the model for the B0s meson decay, while the model for the B0s meson decay is obtained by changing the sign of the ci and di terms in Eq (2)
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