The $B^0\bar{ B^0}$ oscillation frequency $\Delta m_d$ has been measured with the BaBar detector at the PEP-II asymmetric $B$ factory with different experimental techniques. The discussion here is focused on the recent simultaneous measurement of $\Delta m_d$ and $\tau_{ B^0}$ with exclusively reconstructed $B^0 \to D^{ *-}l^+\nu_l$ decays, based on 23 million $B\bar{ B}$ pairs collected by BaBar. The measurements of $\Delta m_d$ with fully reconstructed hadronic decays and with dilepton events are also reviewed. The average BaBar result is $\Delta m_d = 0.500 \pm 0.008 \pm 0.006$ $ps^{ -1}$.
Categories: hep-ex