Measurement of the relative width difference of the B0‐ B¯ 0 system with the ATLAS detector

Abstract

Abstract: This paper presents the measurement of the relative width difference ΔΓ<inf>d</inf>/Γ<inf>d</inf> of the B0‐ B¯ 0 system using the data collected by the ATLAS experiment at the LHC in pp collisions at s=7 TeV and s=8 TeV and corresponding to an integrated luminosity of 25.2 fb−1. The value of ΔΓ<inf>d</inf>/Γ<inf>d</inf> is obtained by comparing the decay-time distributions of B0 → J/ψK<inf>S</inf> and B0 → J/ψK*0(892) decays. The result is ΔΓ<inf>d</inf>/Γ<inf>d</inf> = (−0.1±1.1 (stat.)± 0.9 (syst.)) × 10−2. Currently, this is the most precise single measurement of ΔΓ<inf>d</inf>/Γ<inf>d</inf>. It agrees with the Standard Model prediction and the measurements by other experiments.[Figure not available: see fulltext.] © 2019 Elsevier B.V., All rights reserved.