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Register a new userStudy of $Bto D^{(*)}h$ decays using $62.8~mathrm{fb}^{-1}$ of Belle II data
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We report measurements related to hadronic $B$ decays to final states that contain charm mesons. The analyses are performed on a $62.8~mathrm{fb}^{-1}$ data set collected by the Belle II experiment at a center-of-mass energy corresponding to the mass of the $Upsilon(4S)$ resonance. The measurements reported are for the decay modes $B^-to D^0 h^-$, $B^{-}to D^{*0}h^-$, $bar{B}^{0}to D^{+} h^{-}$ and $bar{B}^{0}to D^{*+} h^{-}$, where $h=pi$ or $K$. These modes are either signal or control channels for measurements related to the unitarity triangle angle $gamma$ in direct or time-dependent $CP$-violation measurements. The reported observables are the ratios between the $Bto D^{(*)}K$ and $Bto D^{(*)}pi$ decay rates, which are found to be in agreement with previous measurements.
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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.
We present the results of the re-discovery of the decay $B^0 to pi^- ell^+ u_ell$ in 34.6 fb$^{-1}$ of Belle II data using hadronic $B$-tagging via the Full Event Interpretation algorithm. We observe 21 signal events on a background of 155 in a fit to the distribution of the square of the missing mass, $M_{mathrm{miss}}^2$, with a significance of 5.69$sigma$, and determine a total branching fraction of (1.58 $pm$ 0.43$_{mathrm{stat}}$ $pm$ 0.07$_{mathrm{sys}}$) $times 10^{-4}$.
We present the results of a search for the rare decays $Bto h uoverline{ u}$, where $h$ stands for $K^+,:K^0_{mathrm{S}},:K^{ast +},:K^{ast 0},:pi^+,:pi^0,:rho^+$ and $rho^{0}$. The results are obtained with $772times10^{6}$ $Boverline{B}$ pairs collected with the Belle detector at the KEKB $e^+ e^-$ collider. We reconstruct one $B$ meson in a semileptonic decay and require a single $h$ meson but nothing else on the signal side. We observe no significant signal and set upper limits on the branching fractions. The limits set on the $Bto K^0_{mathrm{S}} uoverline{ u}$, $B^0to K^{*0} uoverline{ u}$, $Bto pi^+ uoverline{ u}$, $B^0topi^0 uoverline{ u}$, $B^+torho^+ uoverline{ u}$, and $B^0torho^0 uoverline{ u}$ channels are the worlds most stringent.
We report measurements of the $bar{B}^0 to D^{*+} ell^{-} bar{ u}_l$ and $B^- to D^{0} ell^{-} bar{ u}_l$ processes using 34.6 fb$^{-1}$ of collision events recorded by the Belle II experiment at the SuperKEKB asymmetric-energy $e^+ e^-$ collider. For the $B^-to D^{0}ell^-bar u_ell$ channel, we present first studies that isolate this decay from other semileptonic processes and backgrounds. We report a measurement of the $bar{B}^0 to D^{*+} ell^{-} bar{ u}_l$ branching fraction and obtain ${cal B}(bar{B}^0 to D^{*+} ell^{-} bar{ u}_l) = left(4.60 pm 0.05_{mathrm{stat}}pm0.17_{mathrm{syst}} pm 0.45_{pi_s}right) %$, in agreement with the world average. Here, the uncertainties are statistical, systematic, and related to slow pion reconstruction, respectively. The systematic uncertainties are limited by the statistics of auxiliary measurements and will improve in the future. We also report differential branching fractions in five bins of the hadronic recoil parameter $w$ for $bar{B}^0 to D^{*+} ell^{-} bar{ u}_l$, unfolded to account for resolution and efficiency effects.
This note describes the rediscovery of $Btoeta K$ decays in Belle II data, both in the charged and neutral final state: $B_0toeta K_S$ and $B^pmtoeta K^pm$. The $eta$ is searched for in two decay modes: $etatoetapi^+pi^-$ with $etatogammagamma$, and $etatorhogamma$. The analysis uses data collected in 2019 and 2020 at the SuperKEKB asymmetric $e^+e^-$ collider, with an integrated luminosity of $62.8~fb^{-1}$, corresponding to $68.2$ million of $Bbar{B}$ pairs produced. The signal yield is obtained via an unbinned maximum likelihood fit to signal sensitive variables, obtaining branching ratios: $$mathcal{B}left(B^pmtoetaK^pmright) = left(63.4~^{+3.4}_{-3.3},(stat),pm3.2,(syst),right) times10^{-6} $$ $$mathcal{B}left(B_0toetaK_Sright) = left(59.9~^{+5.8}_{-5.5},(stat),pm2.9,(syst),right) times10^{-6} $$ which are consistent with world average.
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