Investigation of Semileptonic $\mathit{B}$ Meson Decays to $\mathit{p}$-Wave Charm Mesons

We have studied semileptonic $B$ meson decays with a $p$-wave charm meson in the final state using $3.29\times {10}^6$ $B\overline{B}$ events collected with the CLEO II detector at the Cornell Electron-Positron Storage Ring. We find a value for the exclusive semileptonic product branching fraction $B(B^{-}\to D_1^0{\ell }^{-}{\overline{\nu }}_{\ell })B(D_1^0\to D^{*+}{\pi }^{-})=(0.373\pm 0.085\pm 0.052\pm 0.024)\%$ and an upper limit for $B(B^{-}\to D_2^{*0}{\ell }^{-}{\overline{\nu }}_{\ell })B(D_2^{*0}\to D^{*+}{\pi }^{-})<0.16\mathrm{}\%$ (90% C.L.). Furthermore, we present the first measurement of the $q^2$ spectrum for $B^{-}\to D_1^0{\ell }^{-}{\overline{\nu }}_{\ell }$.