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Register a new userMeasurement of the Branching Fraction of the Decay $boldsymbol{B^{+}topi^{+}pi^{-}ell^{+} u_ell}$ in Fully Reconstructed Events at Belle
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We present an analysis of the exclusive $B^{+}topi^{+}pi^{-}ell^{+} u_{ell}$ decay, where $ell$ represents an electron or a muon, with the assumption of charge-conjugation symmetry and lepton universality. The analysis uses the full $Upsilon(4S)$ data sample collected by the Belle detector, corresponding to 711 fb$^{-1}$ of integrated luminosity. We select the events by fully reconstructing one $B$ meson in hadronic decay modes, subsequently determining the properties of the other $B$ meson. We extract the signal yields using a binned maximum-likelihood fit to the missing-mass squared distribution in bins of the invariant mass of the two pions or the momentum transfer squared. We measure a total branching fraction of ${{cal B}(B^{+}to pi^{+}pi^{-}ell^{+} u_{ell})= [22.7 ^{+1.9}_{-1.6} (mathrm{stat}) pm 3.5(mathrm{syst}) ]times 10^{-5}}$, where the uncertainties are statistical and systematic, respectively. This result is the first reported measurement of this decay.
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We report branching fraction measurements of the decays $B^+toetaell^+ u_ell$ and $B^+toeta^primeell^+ u_ell$ based on 711~fb$^{-1}$ of data collected near the $Upsilon(4S)$ resonance with the Belle experiment at the KEKB asymmetric-energy $e^+e^-$ collider. This data sample contains 772 million $Bbar B$~events. One of the two $B$~mesons is fully reconstructed in a hadronic decay mode. Among the remaining (signal-$B$) daughters, we search for the $eta$~meson in two decay channels, $etatogammagamma$ and $etatopi^+pi^-pi^0$, and reconstruct the $eta^{prime}$~meson in $eta^primetoetapi^+pi^-$ with subsequent decay of the $eta$ into $gammagamma$. Combining the two $eta$ modes and using an extended maximum likelihood, the $B^+toetaell^+ u_ell$ branching fraction is measured to be $(4.2pm 1.1 (rm stat.)pm 0.3 (rm syst.))times 10^{-5}$. For $B^+toeta^primeell^+ u_ell$, we observe no significant signal and set an upper limit of $0.72times 10^{-4}$ at 90% confidence level.
We report a measurement of the branching fraction of the decay $B rightarrow D^{(*)}pi ell u$. The analysis uses 772$times 10^6$ $Bbar{B}$ pairs produced in $e^+e^-rightarrow Upsilon(4S)$ data recorded by the Belle experiment at the KEKB asymmetric-energy $e^+e^-$ collider. The tagging $B$ meson in the decay is fully reconstructed in a hadronic decay mode. On the signal side, we reconstruct the decay $B rightarrow D^{(*)}pi ell u$ $(ell=e,mu)$. The measured branching fractions are $mathcal{B}(B^+ rightarrow D^-pi^+ ell^+ u)$ = [4.55 $pm$ 0.27 (stat.) $pm$ 0.39 (syst.)]$times 10^{-3}$, $mathcal{B}(B^0 rightarrow bar{D}^0pi^- ell^+ u)$ = [4.05 $pm$ 0.36 (stat.) $pm$ 0.41 (syst.)]$times 10^{-3}$, $mathcal{B}(B^+ rightarrow D^{*-}pi^+ ell^+ u)$ = [6.03 $pm$ 0.43 (stat.) $pm$ 0.38 (syst.)]$times 10^{-3}$, and $mathcal{B}(B^0 rightarrow bar{D}^{*0}pi^- ell^+ u)$ = [6.46 $pm$ 0.53 (stat.) $pm$ 0.52 (syst.)]$times 10^{-3}$. These are in good agreement with the current world average values.
We report a measurement of the inclusive semileptonic $B_s^0$ branching fraction in a $121~fb^{-1}$ data sample collected near the $Upsilon(5S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^+ e^-$ collider. Events containing $B_s^0$ pairs are selected by reconstructing a tag side $D_s^+$ and identifying a signal side lepton $ell^+$ ($ell = e, mu$) that is required to have the same-sign charge to ensure that both originate from different $B_s^0$ mesons. The $B_s^0 rightarrow X^- ell^+ u_ell$ branching fraction is extracted from the ratio of the measured yields of $D_s^+$ mesons and $D_s^+ ell^+$ pairs and the known production and branching fractions. The inclusive semileptonic branching fraction is measured to be $[9.6 pm 0.4text{(stat)} pm 0.7text{(syst)}]~%$.
We measure the branching fractions for the decays $bar{B}^0 to D^{*+} e^{-} bar{ u}_e$ and $bar{B}^0 to D^{*+} mu^{-} bar{ u}_mu$ using $8.70 pm 0.09~{rm fb}^{-1}$ of data collected by the Belle II experiment at the SuperKEKB asymmetric-energy $e^+ e^-$ collider. Candidate signal decays are reconstructed with the subsequent decays $D^{*+}to D^0 pi^+$ and $D^0to K^-pi^+$. We obtain the results ${cal B}(bar{B}^0 to D^{*+} e^{-} bar{ u}_e)$ = $(4.55pm0.14(mathrm{stat})pm0.35 (mathrm{syst})) %$ and ${cal B}(bar{B}^0 to D^{*+} mu^{-} bar{ u}_mu)$ = $(4.84pm 0.13(mathrm{stat})pm0.37(mathrm{syst})) %$, in agreement with the world averages. The measurements serve to validate the full chain of detector operation and calibration, data collection and processing, and production of physics results in the case of semileptonic $B$-meson decays.
We present a first measurement of the $bar{B^{0}} rightarrow D^{*+} ell^{-} u_{ell}$ branching fraction using fully reconstructed $B$ meson decays employing the Full Event Interpretation algorithm. Collision events corresponding to an integrated luminosity of lumi are analyzed, which were recorded by the Belle~II detector operated at the SuperKEKB accelerator complex. We measure$cal{B}(bar{B^{0}} rightarrow D^{*+} ell^{-} u_{ell}) =4.51 pm 0.41_{stat}pm0.27_{syst} pm0.45_{pi_s}$, with the first and second error denoting the statistical and systematic uncertainty, respectively, and the third dominant uncertainty is from the slow pion reconstruction efficiency.
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