We use a sample of $384\times {10}^6$ $B\overline{B}$ events collected with the BABAR detector at the PEP-II $e^{+}{e}^{-}$ collider to study angular distributions in the rare decays $B\to K^{*}{\ell }^{+}{\ell }^{-}$, where ${\ell }^{+}{\ell }^{-}$ is either $e^{+}{e}^{-}$ or ${\mu }^{+}{\mu }^{-}$. For low dilepton invariant masses, $m_{\ell \ell }<2.5\mathrm{GeV}/c^2$, we measure a lepton forward-backward asymmetry ${\mathcal{A}}_{\mathrm{FB}}={0.24}_{-0.23}^{+0.18}\pm 0.05$ and $K^{*}$ longitudinal polarization $F_L=0.35\pm 0.16\pm 0.04$. For $m_{\ell \ell }>3.2\mathrm{GeV}/c^2$, we measure ${\mathcal{A}}_{\mathrm{FB}}={0.76}_{-0.32}^{+0.52}\pm 0.07$ and $F_L={0.71}_{-0.22}^{+0.20}\pm 0.04$.

• Received 28 April 2008

DOI:https://doi.org/10.1103/PhysRevD.79.031102