Measurement of CP violation in $B^0\overline{B^0}$ mixing using partially reconstructed $B^0 \to D^*\ell \nu$ decays and Kaon Tags

We present a measurement of the parameter $|q/p|$ governing the CP violation in $B\kern 0.18em\overline{\kern -0.18em B}^0$ mixing. The analysis is based on a large sample of $B^0 \to D^*\ell \nu$ events, partially reconstructed from a data sample of about 460 million $B\kern 0.18em\overline{\kern -0.18em B}$ pairs, collected with the {\sl B{\scriptsize A}B{\scriptsize AR}} detector at the PEP-II asymmetric-energy $B$ factory at SLAC. The flavor of the unreconstructed $B^0$ mesons is determined by means of a kaon tag technique.