Measurement of the B$^0_\mathrm{s}$ $\to$ J/$\psi$K$^0_\mathrm{S}$ effective lifetime from proton-proton collisions at $\sqrt{s}$ = 13 TeV

TL;DR

This paper reports a highly precise measurement of the B_s meson effective lifetime in a specific decay channel using CMS data at 13 TeV, confirming theoretical expectations.

Contribution

It provides the most precise measurement to date of the B_s effective lifetime in the J/psi K0_S decay channel using a novel two-dimensional fit approach.

Findings

Effective lifetime measured as 1.59 ± 0.07 (stat) ± 0.03 (syst) ps.

Result is consistent with theoretical predictions.

Achieves the most precise measurement for this parameter to date.

Abstract

The effective lifetime of the B$^0_\mathrm{s}$ meson in the decay B$^0_\mathrm{s}$ $\to$ J/$\psi$K$^0_\mathrm{S}$ is measured using data collected during 2016-2018 with the CMS detector in $\sqrt{s}$ = 13 TeV proton-proton collisions at the LHC, corresponding to an integrated luminosity of 140 fb$^{-1}$. The effective lifetime is determined by performing a two-dimensional unbinned maximum likelihood fit to the B$^0_\mathrm{s}$ meson invariant mass and proper decay time distributions. The resulting value of 1.59 $\pm$ 0.07 (stat) $\pm$ 0.03 (syst) ps is the most precise measurement to date and is in good agreement with the expected value.