$B$ meson decays to charmless meson pairs containing $\eta$ or $\eta \prime$ mesons

We present updated measurements of the branching fractions for $B^0$ meson decays to $\eta K^0$, $\eta \eta$, $\eta \varphi$, $\eta \omega$, ${\eta }^{\prime }{K}^0$, ${\eta }^{\prime }{\eta }^{\prime }$, ${\eta }^{\prime }\varphi$, and ${\eta }^{\prime }\omega$, and branching fractions and $CP$-violating charge asymmetries for $B^{+}$ decays to $\eta {\pi }^{+}$, $\eta K^{+}$, ${\eta }^{\prime }{\pi }^{+}$, and ${\eta }^{\prime }{K}^{+}$. The data represent the full data set of $467\times {10}^6$ $B\overline{B}$ pairs collected with the BABAR detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ collider at the SLAC National Accelerator Laboratory. Besides large signals for the four charged $B$ decay modes and for $B^0\to {\eta }^{\prime }{K}^0$, we find evidence for three $B^0$ decay modes at greater than $3.0\sigma$ significance. We find $\mathcal{B}(B^0\to \eta K^0)=({1.15}_{-0.38}^{+0.43}\pm 0.09)\times {10}^{-6}$, $\mathcal{B}(B^0\to \eta \omega )=({0.94}_{-0.30}^{+0.35}\pm 0.09)\times {10}^{-6}$, and $\mathcal{B}(B^0\to {\eta }^{\prime }\omega )=({1.01}_{-0.38}^{+0.46}\pm 0.09)\times {10}^{-6}$, where the first (second) uncertainty is statistical (systematic). For the $B^{+}\to \eta K^{+}$ decay mode, we measure the charge asymmetry ${\mathcal{A}}_{\mathrm{ch}}(B^{+}\to \eta K^{+})=-0.36\pm 0.11\pm 0.03$.

Figure 1

Examples of Feynman diagrams involved in decays studied in this paper: (a), (b) penguin diagrams, (c) Cabibbo-suppressed tree diagram, (d) gluonic penguin diagram.

Figure 2

The $B^0$ candidate $m_{\mathrm{ES}}$ and $\Delta E$ projections for $\eta K_S^0$ [(a), (b)], $\eta \omega$ [(c), (d)], ${\eta }^{\prime }{K}_S^0$ [(e), (f)], and ${\eta }^{\prime }\omega$ [(g), (h)] decays, with subdecays combined. Points with errors represent the data, solid curves the full fit functions, and dashed curves the background functions.

Figure 3

The $B^{+}$ candidate $m_{\mathrm{ES}}$ and $\Delta E$ projections for $\eta {\pi }^{+}$ [(a), (b)], $\eta K^{+}$ [(c), (d)], ${\eta }^{\prime }{\pi }^{+}$ [(e), (f)], and ${\eta }^{\prime }{K}^{+}$ [(g), (h)] decays, with subdecays combined. Points with errors represent the data, solid curves the full fit functions, and dashed curves the background functions.