Observation of $B^{+}\to \phi \phi K^{+}$ and Evidence for $B^0\to \phi \phi K^0$ below ${\eta }_c$ Threshold

We report measurements of the decays $B^{+}\to \varphi \varphi K^{+}$ and $B^0\to \varphi \varphi K^0$ using a sample of $231\times {10}^6$ $B\overline{B}$ pairs collected with the BABAR detector at the PEP-II asymmetric-energy $B$ factory at the Stanford Linear Accelerator Center. The branching fractions are measured to be $\mathcal{B}(B^{+}\to \varphi \varphi K^{+})=\mathbf{(}7.5\pm 1.0(\mathrm{stat})\pm 0.7(\mathrm{syst})\mathbf{)}\times {10}^{-6}$ and $\mathcal{B}(B^0\to \varphi \varphi K^0)=\mathbf{(}{4.1}_{-1.4}^{+1.7}(\mathrm{stat})\pm 0.4(\mathrm{syst})\mathbf{)}\times {10}^{-6}$ for a $\varphi \varphi$ invariant mass below $2.85\mathrm{GeV}/c^2$.

Figure 1

The projected $m_{\mathrm{ES}}$ distributions of events with $|\Delta E|<0.05\mathrm{GeV}$ for (a) $B^{+}\to \varphi \varphi K^{+}$ and (b) $B^0\to \varphi \varphi K^0$, and the projected $\Delta E$ distributions of events with $m_{\mathrm{ES}}>5.27\mathrm{GeV}/c^2$ for (c) $B^{+}\to \varphi \varphi K^{+}$ and (d) $B^0\to \varphi \varphi K^0$. Points with error bars represent the data, solid lines the total PDF, and dashed lines the background PDF.

Figure 2

The projected $m_{\varphi \varphi }$ distributions of events with $|\Delta E|<0.05\mathrm{GeV}$ and $m_{\mathrm{ES}}>5.27\mathrm{GeV}/c^2$ for the $B^{+}\to \varphi \varphi K^{+}$ decay mode. The points with error bars represent the data in the signal region, and the shaded histogram represents the mass distribution of expected background from the $\Delta E$ sideband.