Measurements of $CP$-violating asymmetries and branching fractions in $B$ decays to $\omega K$ and $\omega \pi$

We present measurements of $CP$-violating asymmetries and branching fractions for the decays $B^{+}\to \omega {\pi }^{+}$, $B^{+}\to \omega K^{+}$, and $B^0\to \omega K^0$. The data sample corresponds to $232\times {10}^6$ $B\overline{B}$ pairs produced by $e^{+}{e}^{-}$ annihilation at the ${\rm Y}(4S)$ resonance. For the decay $B^0\to \omega K_S^0$, we measure the time-dependent $CP$-violation parameters $\mathrm{S}={0.51}_{-0.39}^{+0.35}\pm 0.02$, and $\mathrm{C}=-{0.55}_{-0.26}^{+0.28}\pm 0.03$. We also measure the branching fractions, in units of ${10}^{-6}$, $\mathcal{B}(B^{+}\to \omega {\pi }^{+})=6.1\pm 0.7\pm 0.4$, $\mathcal{B}(B^{+}\to \omega K^{+})=6.1\pm 0.6\pm 0.4$, and $\mathcal{B}(B^0\to \omega K^0)=6.2\pm 1.0\pm 0.4$, and charge asymmetries ${\mathcal{A}}_{\mathrm{ch}}(B^{+}\to \omega {\pi }^{+})=-0.01\pm 0.10\pm 0.01$ and ${\mathcal{A}}_{\mathrm{ch}}(B^{+}\to \omega K^{+})=0.05\pm 0.09\pm 0.01$.

Figure 1

The $B$ candidate $m_{\mathrm{ES}}$ and $\Delta E$ projections for $B^{+}\to \omega {\pi }^{+}$ (a, b), $B^{+}\to \omega K^{+}$ (c, d), and $B^0\to \omega K^0$ (e, f) shown for a signal-enhanced subset of the data. Points with error bars represent the data, the solid line the fit function, and the dashed line the background components. Note that the $\omega K^{+}$ signal in the $\Delta E$ plot is displaced from zero since $\Delta E$ is defined for the $\omega {\pi }^{+}$ hypothesis.

Figure 2

Projections onto $\Delta t$ for $B^0\to \omega K^0$. Data (points with errors), the fit function (solid line), background component (dashed line), and signal component (dotted line), for events in which the tag meson is (a) $B^0$ and (b) ${\overline{B}}^0$, and (c) the asymmetry $(N_{B^0}-N_{{\overline{B}}^0})/(N_{B^0}+N_{{\overline{B}}^0})$.