Measurement of Effective \(B_{s}^{0} \to J{\text{/}}\psi K_{S}^{0}\) Lifetime Using Run-II CMS Data

The effective lifetime for the decay \(B_{s}^{0} \to J{\text{/}}\psi K_{S}^{0}\) is reported using the data from pp collision at centre of mass energy \(\sqrt s \) = 13 TeV recorded by CMS experiment at the LHC during 2016, 2017 and 2018. The data sample corresponds to an integrated luminosity of 140 fb^–1. The measurement uses the two-dimensional unbinned maximum likelihood (UML) fit to B-invariant mass and the decay time to extract the observable. Effective lifetime is measured as 1.59 \( \pm \) 0.07(stat) \( \pm \) 0.03(syst) ps, which is in good agreement with the standard model prediction and stands as the most precise result to date.