Measurement of Branching Fractions and Charge Asymmetries in $B^{+}$ Decays to $\eta {\pi }^{+}$, $\eta K^{+}$, $\eta {\rho }^{+}$, and ${\eta }^{\prime }{\pi }^{+}$, and Search for $B^0$ Decays to $\eta K^0$ and $\eta \omega$

We present measurements of branching fractions and charge asymmetries for six $B$-meson decay modes with an $\eta$ or ${\eta }^{\prime }$ meson in the final state. The data sample corresponds to $232\times {10}^6$ $B\overline{B}$ pairs collected with the BABAR detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ $B$ Factory at SLAC. We measure the branching fractions (in units of ${10}^{-6}$): $\mathcal{B}(B^{+}\to \eta {\pi }^{+})=5.1\pm 0.6\pm 0.3$, $\mathcal{B}(B^{+}\to \eta K^{+})=3.3\pm 0.6\pm 0.3$, $\mathcal{B}(B^0\to \eta K^0)=1.5\pm 0.7\pm 0.1$ ($<2.5$ at 90% C.L.), $\mathcal{B}(B^{+}\to \eta {\rho }^{+})=8.4\pm 1.9\pm 1.1$, $\mathcal{B}(B^0\to \eta \omega )=1.0\pm 0.5\pm 0.2$ ($<1.9$ at 90% C.L.), and $\mathcal{B}(B^{+}\to {\eta }^{\prime }{\pi }^{+})=4.0\pm 0.8\pm 0.4$, where the first uncertainty is statistical and second systematic. For the charged modes we also determine the charge asymmetries, all found to be compatible with zero.

Figure 1

The $B$ candidate $m_{\mathrm{ES}}$ (left) and $\Delta E$ (right) projections obtained with a cut on the signal likelihood (see text) for $B^{+}\to \eta {\rho }^{+}$ (a), (b), $B^{+}\to {\eta }^{\prime }{\pi }^{+}$ (c), (d), and combined $B^{+}\to \eta {\pi }^{+}$ and $B^{+}\to \eta K^{+}$ (e), (f). Points with uncertainties represent the data, solid curves the full fit functions, dashed (dot-dashed) curves the full (charmless $B\overline{B}$) background functions, and the dotted curves the background plus signal $\eta K^{+}$ functions.