Measurement of the decay $B^0\to \ddot{I}{€}^{-}{\ell }^{+}\hat{I}½$ and determination of $|V_{ub}|$

Abstract

We present a measurement of the charmless semileptonic decay $B^0\to \ddot{I}{€}^{-}{\ell }^{+}\hat{I}½$ using a data sample containing 657$\times 10^6$ $B\bar{B}$ events collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider operating near the $\hat{I}\yen (4S)$ resonance. We determine the total branching fraction of the decay, $\mathcal{B}(B^0\to \ddot{I}{€}^{-}{\ell }^{+}\hat{I}½)=(1.49\pm 0.04(\mathrm{stat})\pm 0.07(\mathrm{syst}))\times 10^{-4}$. We also report a new precise measurement of the differential decay rate, and extract the Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$ using model-independent and -dependent approaches. From a simultaneous fit to the measured differential decay rate and lattice QCD results, we obtain $|V_{ub}|=(3.43\pm 0.33)\times 10^{-3}$, where the error includes both statistical and systematic uncertainties.

8 pages, 3 figures, Submitted to PRD(RC)