Branching fraction measurement ofB+→ωℓ+νdecays

We present a measurement of the $B^{+}\to \omega {\ell }^{+}\nu$ branching fraction based on a sample of 467 million $B\overline{B}$ pairs recorded by the BABAR detector at the SLAC PEP-II $e^{+}{e}^{-}$ collider. We observe $1125\pm 131$ signal decays, corresponding to a branching fraction of $\mathcal{B}(B^{+}\to \omega {\ell }^{+}\nu )=(1.21\pm 0.14\pm 0.08)\times {10}^{-4}$, where the first error is statistical and the second is systematic. The dependence of the decay rate on $q^2$, the invariant mass squared of the leptons, is compared to QCD predictions of the form factors based on a quark model and light-cone sum rules.