Measurement of the Decay B- --> D*0 e- nubar

Abstract

Using 226 million $B\bar{B}$ events recorded on the ${\rm Y}(4S)$ resonance with the BABAR detector at the SLAC $e^{+}{e}^{-}$ storage rings PEPII, we reconstruct $B^{-}\to D^{\ast 0}{e}^{-}{\bar{\nu }}_e$ decays using the decay chain $D^{\ast 0}\to D^0{\pi }^0$ and $D^0\to K^{-}{\pi }^{+}$. From the dependence of their differential rate on $w$, the product of the four-velocities of $B^{-}${} and $D^{\ast 0}$, and using the description of the form factor $F(w)$ by Caprini et al., we obtain the preliminary results ${\rho }_{A_1}^2=1.15\pm 0.06\pm 0.08$, $F(1)\cdot |V_{cb}|=(36.3\pm 0.6\pm 1.4)\cdot 10^{-3}$, and $\mathcal{B}(B^{-}\to D^{\ast 0}{e}^{-}{\bar{\nu }}_e)=(5.71\pm 0.08\pm 0.41)$. The first errors are statistical and the second ones are systematic. \\

8 pages, 2 postscript figures, submitted to EPS2007