Precision measurements of B-meson decays at ATLAS

Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holešovicˇkách 2, 18000 Prague 8, Czech Republic

^* e-mail: marek.biros@cern.ch

Published online: 20 November 2024

Abstract

The precise measurement of the CP-violating phase ϕ_s, the average decay width Γ_s and the difference between the widths of the light and heavy mass eigenstates ΔΓ_s is presented in the $B_s^0$$${B_s^0} $$ → J/ψϕ decay channel. Data of pp collisions at √s = 13 TeV are used, corresponding to 80.5 fb⁻¹ of integrated lu-minosity collected by the ATLAS detector at the Large Hadron Collider in years 2015–2017. Results are statistically combined with the previous measurement with 19.2 fb⁻¹ data with 7 and 8 TeV energy. The measured values are:

ϕ_s = −0.087 ± 0.036 (stat.) ± 0.021 (syst.)

Γ_s = 0.6703 ± 0.0014 (stat.) ± 0.0018 (syst.)

ΔΓ_s = 0.0657 ± 0.0043 (stat.) ± 0.0037 (syst.).

Moreover, a study estimating the ATLAS detector performance in measuring the CP-violating phase ϕ_s after the HL-LHC upgrade is presented.