Measurement of the lifetime of the Bc+ meson using the Bc+→J/ψπ+ decay mode

The difference in total widths between the Bc+ and B+B+ mesons is measured using a data sample corresponding to an integrated luminosity of 3.0 fb−13.0 fb−1 collected by the LHCb experiment in 7 and 8 TeV centre-of-mass energy proton–proton collisions at the LHC. Through the study of the time evolution of Bc+→J/ψπ+ and B+→J/ψK+B+→J/ψK+ decays, the width difference is measured to beΔΓ≡ΓBc+−ΓB+=4.46±0.14±0.07 mm−1c, where the first uncertainty is statistical and the second systematic. The known lifetime of the B+B+ meson is used to convert this to a precise measurement of the Bc+ lifetime,τBc+=513.4±11.0±5.7 fs, where the first uncertainty is statistical and the second is systematic.