# Measurement of the CP-violating phase $\phi_s$ and the $B^0_s$ meson decay width difference with $B^0_s \to J/\psi\phi$ decays in ATLAS

Abstract : A measurement of the $B^0_s$ decay parameters in the $B^0_s \to J/\psi\phi$ channel using an integrated luminosity of 14.3 $\mathrm{fb}^{-1}$ collected by the ATLAS detector from 8 TeV $pp$ collisions at the LHC is presented. The measured parameters include the $CP$-violating phase $\phi_s$, the decay width $\Gamma_s$ and the width difference between the mass eigenstates $\Delta\Gamma_s$. The values measured for the physical parameters are statistically combined with those from 4.9 $\mathrm{fb}^{-1}$ of 7 TeV data, leading to the following: \begin{eqnarray*} \phi_s & = & -0.098 \pm 0.084\;\mathrm{(stat.)} \pm 0.040\;\mathrm{(syst.)\;rad} \\ \Delta\Gamma_s & = & 0.083 \pm 0.011\;\mathrm{(stat.)} \pm 0.007\;\mathrm{(syst.)\;ps}^{-1} \\ \Gamma_s & = & 0.677 \pm 0.003\;\mathrm{(stat.)} \pm 0.003\;\mathrm{(syst.)\;ps}^{-1}. \end{eqnarray*} In the analysis the parameter $\Delta\Gamma_s$ is constrained to be positive. Results for $\phi_s$ and $\Delta\Gamma_s$ are also presented as 68% and 95% likelihood contours in the $\phi_s$-$\Delta\Gamma_s$ plane. Also measured in this decay channel are the transversity amplitudes and corresponding strong phases. All measurements are in agreement with the Standard Model predictions.
Type de document :
Article dans une revue
Journal of High Energy Physics, Springer Verlag (Germany), 2016, 08, pp.147. 〈10.1007/JHEP08(2016)147〉

http://hal.in2p3.fr/in2p3-01255785
Contributeur : Emmanuelle Vernay <>
Soumis le : jeudi 14 janvier 2016 - 08:48:48
Dernière modification le : mardi 13 février 2018 - 13:28:06

### Citation

G. Aad, S. Albrand, J. Brown, J. Collot, S. Crépé-Renaudin, et al.. Measurement of the CP-violating phase $\phi_s$ and the $B^0_s$ meson decay width difference with $B^0_s \to J/\psi\phi$ decays in ATLAS. Journal of High Energy Physics, Springer Verlag (Germany), 2016, 08, pp.147. 〈10.1007/JHEP08(2016)147〉. 〈in2p3-01255785〉

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