The ATLAS Collaboration,Aaboud, M.2016-10-052016-10-052016Journal of High Energy Physics (JHEP), 2016; 2016(6):081-0-081-391126-67081029-8479http://hdl.handle.net/2440/101578Published: June 14, 2016This paper presents the measurement of the relative width difference ΔΓd/Γd 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 ΔΓd/Γd is obtained by comparing the decay-time distributions of B0 → J/ψKS and B0 → J/ψK*0(892) decays. The result is ΔΓd/Γd = (−0.1±1.1 (stat.)± 0.9 (syst.)) × 10−2. Currently, this is the most precise single measurement of ΔΓd/Γd. It agrees with the Standard Model prediction and the measurements by other experiments.en© The Author(s) 2016. Open Access. This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.B physics; Hadron-Hadron scattering (experiments)Journal article003005178410.1007/JHEP06(2016)0810003791779000012-s2.0-84978387429251682