# Measurement of the CP-violating weak phase $ϕ_s$ and the decay width difference $ΔΓ_s$ using the $B^{0}_{s}→J/ψϕ(1020)$ decay channel in pp collisions at $\sqrt{s} = 8$ TeV

CMS Collaboration; Canelli, F; Chiochia, V; Kilminster, B; Robmann, P; et al (2016). Measurement of the CP-violating weak phase $ϕ_s$ and the decay width difference $ΔΓ_s$ using the $B^{0}_{s}→J/ψϕ(1020)$ decay channel in pp collisions at $\sqrt{s} = 8$ TeV. Physics Letters B, 757:97-120.

## Abstract

The CP-violating weak phase $ϕ_s$ of the $B^{0}_{s}$ meson and the decay width difference $ΔΓ_s$ of the Bs0 light and heavy mass eigenstates are measured with the CMS detector at the LHC using a data sample of $B^{0}_{s}→J/ψϕ(1020)→μ^{+}μ^{−}K^{+}K^{−}$ decays. The analysed data set corresponds to an integrated luminosity of 19.7fb$^{−1}$ collected in pp collisions at a centre-of-mass energy of 8TeV . A total of 49 200 reconstructed $B^{0}_{s}$ decays are used to extract the values of $ϕ_s$ and $ΔΓ_s$ by performing a time-dependent and flavour-tagged angular analysis of the $μ^{+}μ^{−}K^{+}K^{−}$ final state. The weak phase is measured to be $ϕ_s$=−0.075±0.097(stat)±0.031(syst) rad , and the decay width difference is $ΔΓ_s$=0.095±0.013(stat)±0.007(syst) ps$^{−1}$.

## Abstract

The CP-violating weak phase $ϕ_s$ of the $B^{0}_{s}$ meson and the decay width difference $ΔΓ_s$ of the Bs0 light and heavy mass eigenstates are measured with the CMS detector at the LHC using a data sample of $B^{0}_{s}→J/ψϕ(1020)→μ^{+}μ^{−}K^{+}K^{−}$ decays. The analysed data set corresponds to an integrated luminosity of 19.7fb$^{−1}$ collected in pp collisions at a centre-of-mass energy of 8TeV . A total of 49 200 reconstructed $B^{0}_{s}$ decays are used to extract the values of $ϕ_s$ and $ΔΓ_s$ by performing a time-dependent and flavour-tagged angular analysis of the $μ^{+}μ^{−}K^{+}K^{−}$ final state. The weak phase is measured to be $ϕ_s$=−0.075±0.097(stat)±0.031(syst) rad , and the decay width difference is $ΔΓ_s$=0.095±0.013(stat)±0.007(syst) ps$^{−1}$.

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Item Type: Journal Article, refereed, original work 07 Faculty of Science > Physics Institute 530 Physics English 2016 06 Jan 2017 13:37 06 Jan 2017 13:37 Elsevier 0370-2693 Publisher DOI. An embargo period may apply. https://doi.org/10.1016/j.physletb.2016.03.046

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