Measurement of the {B} _{c} ^+ meson lifetime using {B} _{c} ^+ \rightarrow {{J} /\psi } \mu ^+ \upnu _\mu X decays

The lifetime of the \({B} _{c} ^+\) meson is measured using semileptonic decays having a \(J/\psi \) meson and a muon in the final state. The data, corresponding to an integrated luminosity of \(2 \text{ fb }^{-1} \), are collected by the LHCb detector in \(pp\) collisions at a centre-of-mass energy of 8 TeV. The measured lifetime is $$\begin{aligned} \tau = 509\pm 8\pm 12\mathrm {~fs}, \end{aligned}$$ where the first uncertainty is statistical and the second is systematic.