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A precise measurement of the Bº meson oscillation frequency

The oscillation frequency, md , of B0 mesons 
is measured using semileptonic decays with a D− or D∗− 
meson in the final state. The data sample corresponds to 
3.0 fb−1 of pp collisions, collected by the LHCb experiment 
at centre-of-mass energies √s = 7 and 8 TeV. A combination 
of the two decay modes gives md = (505.0 ± 2.1 ± 
1.0) ns−1, where the first uncertainty is statistical and the 
second is systematic. This is the most precise single measurement 
of this parameter. It is consistent with the current 
world average and has similar precision.