000002117 001__ 2117
000002117 005__ 20200922092451.0
000002117 037__ $$aBELLE2-CONF-PH-2020-012
000002117 041__ $$aeng
000002117 100__ $$aF. Abudinén
000002117 245__ $$aMeasurements of branching fractions and CP-violating charge asymmetries in charmless $B$ decays reconstructed in 2019--2020 Belle~II data
000002117 260__ $$a$$c2020-09-20
000002117 300__ $$a33
000002117 500__ $$aPrepared for ICHEP2020
000002117 520__ $$aWe report on first measurements of  branching fractions~($\mathcal{B}$) and CP-violating charge asymmetries~($\mathcal{A}_{\rm CP}$) in charmless $B$ decays at Belle~II.  We use a sample of electron-positron collisions collected in 2019 and 2020 at the $\Upsilon(4S)$ resonance and  corresponding to $34.6$\,fb$^{-1}$ of integrated luminosity. We use simulation to determine optimized event selections. The $\Delta E$ distributions of the resulting samples, restricted in $M_{\rm bc}$, are fit to determine signal yields ranging from 35 to 450 decays for the channels  \mbox{$B^0 \to K^+\pi^-$},  \mbox{$B^+ \to K^+\pi^0$}, \mbox{$B^+ \to \PKzS\pi^+$}, \mbox{$B^0 \to \PKzS\pi^0$}, \mbox{$B^0 \to \pi^+\pi^-$},  \mbox{$B^+ \to \pi^+\pi^0$},  \mbox{$B^+ \to K^+K^-K^+$},  and \mbox{$B^+ \to K^+\pi^-\pi^+$}.  Signal yields are corrected for efficiencies determined from simulation and control data samples to obtain the following results: \begin{center} $\mathcal{B}(B^0 \to K^+\pi^-) = [18.9 \pm 1.4(\rm stat) \pm 1.0(\rm syst)]\times 10^{-6}$, \end{center} \begin{center} $\mathcal{B}(B^+ \to K^+\pi^0) = [12.7 ^{+2.2}_{-2.1} (\rm stat)\pm 1.1(\rm syst)]\times 10^{-6}$, \end{center} \begin{center} $\mathcal{B}(B^+ \to K^0\pi^+) = [21.8 ^{+3.3}_{-3.0}(\rm stat) \pm 2.9(\rm syst)]\times 10^{-6}$, \end{center} \begin{center} $\mathcal{B}(B^0 \to K^0\pi^0) = [10.9^{+2.9}_{-2.6} (\rm stat)\pm 1.6(\rm syst)]\times 10^{-6}$, \end{center} \begin{center} $\mathcal{B}(B^0 \to \pi^+\pi^-) = [5.6 ^{+1.0}_{-0.9}(\rm stat) \pm 0.3(\rm syst)]\times 10^{-6}$, \end{center} \begin{center} $\mathcal{B}(B^+ \to \pi^+\pi^0) = [5.7 \pm 2.3 (\rm stat)\pm 0.5(\rm syst)]\times 10^{-6}$, \end{center} \begin{center} $\mathcal{B}(B^+ \to K^+K^-K^+) = [32.0 \pm 2.2(\rm stat.) \pm 1.4 (\rm syst)]\times 10^{-6}$,  \end{center} \begin{center} $\mathcal{B}(B^+ \to K^+\pi^-\pi^+) = [48.0 \pm 3.8 (\rm stat)\pm 3.3 (\rm syst)]\times 10^{-6}$, \end{center} \begin{center} $\mathcal{A}_{\rm CP}(B^0 \to K^+\pi^-) = 0.030 \pm 0.064 (\rm stat) \pm 0.008(\rm syst)$, \end{center} \begin{center} $\mathcal{A}_{\rm CP}(B^+ \to K^+\pi^0) = 0.052 ^{+0.121}_{-0.119} (\rm stat)\pm 0.022(\rm syst)$, \end{center} \begin{center} $\mathcal{A}_{\rm CP}(B^+ \to K^0\pi^+) = -0.072 ^{+0.109}_{-0.114}(\rm stat) \pm 0.024(\rm syst)$, \end{center} \begin{center} $\mathcal{A}_{\rm CP}(B^+ \to \pi^+\pi^0) = -0.268 ^{+0.249}_{-0.322} (\rm stat)\pm 0.123(\rm syst)$, \end{center} \begin{center} $\mathcal{A}_{\rm CP}(B^+ \to K^+K^-K^+) = -0.049 \pm 0.063(\rm stat) \pm 0.022 (\rm syst)$, and  \end{center} \begin{center} $\mathcal{A}_{\rm CP}(B^+ \to K^+\pi^-\pi^+) = -0.063 \pm 0.081 (\rm stat)\pm 0.023(\rm syst)$. \end{center}  These are the first measurements in charmless decays reported by Belle~II. Results are compatible with known determinations and show detector performance comparable with the best Belle results offering a reliable basis to assess projections for future reach.
000002117 6531_ $$aCharmless, Phase 3, CP violation
000002117 700__ $$aP.-T. Chang
000002117 700__ $$aY.-C. (Janice) Chen
000002117 700__ $$aE. Ganiev
000002117 700__ $$aC.-H. Li
000002117 700__ $$aR. Manfredi
000002117 700__ $$aH.-G. Moser
000002117 700__ $$aS. Raiz
000002117 700__ $$aM. Reif
000002117 700__ $$aD. Tonelli
000002117 700__ $$aB. Wach
000002117 8560_ $$fdiego.tonelli@desy.de
000002117 8564_ $$uhttps://docs.belle2.org/record/2117/files/BELLE2-CONF-PH-2020-012.pdf