Search for B-meson decays to b1rho and b1K*

We present a search for decays of $B$ mesons to final states with a $b\mathrm{\_}1$ meson and a $\rho$ or $K^{\ast }(892)$ meson. The search is based on a data sample consisting of 465 million $BB$ pairs collected by the {\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}} detector at the SLAC National Accelerator Laboratory. We do not observe any statistically significant signal. The upper limits we set on the branching fractions range from 1.4 to $8.0\times {10}^{-6}$ at the 90% confidence level (C.L.), including systematic uncertainties.