A precise measurement of the $B^0$ meson oscillation frequency

The oscillation frequency, $\mathrm{\Delta }{m}_d$, of $B^0$ mesons is measured using semileptonic decays with a $D^{-}$ or $D^{\ast -}$ meson in the final state, in a data sample of $pp$ collisions collected by the LHCb detector corresponding to an integrated luminosity of 3.0$f{b}^{-1}$. A combination of the two decay modes gives $\mathrm{\Delta }{m}_d=(505.0\pm 2.1\pm 1.0)\mathrm{n}{\mathrm{s}}^{-1}$, where the first uncertainty is statistical and the second is systematic. This is the most precise single measurement of this parameter. It is compatible with the current world average and has similar precision.