This paper reports the first ATLAS measurement of the B-s(0) -> mu mu effective lifetime. The measurement is based on the data collected in 2015-2016, amounting to 26.3 fb(-1) of 13TeV LHC proton-proton collisions. The proper decay-time distribution of 58 +/- 13 background-subtracted signal candidates is fit with simulated signal templates parameterised as a function of the B-s(0) effective lifetime, with statistical uncertainties extracted through a Neyman construction. The resulting effective measurement of the B-s(0) -> mu mu lifetime is 0.99(-0.07)(+0.42) (stat.) +/- 0.17 (syst.) ps and it is found to be consistent with the Standard Model.

Aad, G., Abbott, B., Abeling, K., Abicht, N.J., Abidi, S.H., Aboulhorma, A., et al. (2023). Measurement of the $$ {B}_s^0 $$ → μμ effective lifetime with the ATLAS detector. JOURNAL OF HIGH ENERGY PHYSICS, 2023(9), 1-31 [10.1007/JHEP09(2023)199].

Measurement of the $$ {B}_s^0 $$ → μμ effective lifetime with the ATLAS detector

Alberghi, G. L.;Alfonsi, F.;Bindi, M.;Boscherini, D.;Carratta, G.;Cavalli, N.;De Castro, S.;Fabbri, F.;Fabbri, L.;Franchini, M.;Gabrielli, A.;Lasagni Manghi, F.;Massa, L.;Monzani, S.;