Selection of $B^+ \to \bar{D}^0\pi^+$ and $B^+ \to \bar{D}^0\mu\nu_\mu$ to control flavour tagging in LHCb

The channels $B^+\to\bar{D}^0\pi^+$ and $B^+\to\bar{D}^0\mu\nu_\mu$ are studied in both signal and generic bb Monte Carlo. With an integrated luminosity of 2fb-1, we expect 1 million $B^+\to\bar{D}^0\pi^+$ events triggered and selected with B/S=0.1 and 2.4M $B^+\to\bar{D}^0\mu\nu_\mu$ events with B/S=0.7. These channels are useful to calibrate the opposite side mistag fraction. With only 0.1fb-1, we expect a relative uncertainty on the opposite side mistag of 0.6%