Evidence for the $B^0\to p\overline{p}{K}^{*0}$ and $B^{+}\to {\eta }_c{K}^{*+}$ decays and study of the decay dynamics of $B$ meson decays into $p\overline{p}h$ final states

With a sample of $232\times {10}^6$ $\mathit{{\rm Y}}(4S)\to B\overline{B}$ events collected with the BABAR detector, we study the decays of $B$ mesons to $p\overline{p}h$ final states, where $h={\pi }^{+}$, $K_S^0$, $K^{*0}$, or $K^{*+}$. We report evidence for the $B^0\to p\overline{p}{K}^{*0}$ decay, with a branching fraction $(1.47\pm 0.45(\mathrm{stat})\pm 0.40(\mathrm{syst}))\times {10}^{-6}$, and for the $B^{+}\to {\eta }_c{K}^{*+}$ decay, with the branching fraction of $\mathcal{B}(B^{+}\to {\eta }_c{K}^{*+})\times \mathcal{B}({\eta }_c\to p\overline{p})=({1.57}_{-0.45}^{+0.56}(\mathrm{stat}{)}_{-0.36}^{+0.46}(\mathrm{syst}))\times {10}^{-6}$, and provide improved measurements of the branching fractions of the other modes of this type. We also report the measurements of the charge asymmetry consistent with zero in the $B^{+}\to p\overline{p}{\pi }^{+}$, $B^0\to p\overline{p}{K}^{*0}$, and $B^{+}\to p\overline{p}{K}^{*+}$ modes. No evidence is found for the pentaquark candidate ${\Theta }^{+}$ in the mass range 1.52 to $1.55\mathrm{GeV}/c^2$, decaying into $p{K}_S^0$, or the glueball candidate $f_J(2220)$ in the mass range $2.2<m_{p\overline{p}}<2.4\mathrm{GeV}/c^2$, and branching fraction limits are established for both at the ${10}^{-7}$ level.

Figure 1

Distributions (points with error bars) of $\Delta E$ and $m_{\mathrm{ES}}$ for data candidates in all-other region passing loose selection in the $B^0\to p\overline{p}{K}^0$ (a)–(b), $B^{+}\to p\overline{p}{K}^{*+}$ (c)–(d), $B^0\to p\overline{p}{K}^{*0}$ (e)–(f), $B^{+}\to p\overline{p}{\pi }^{+}$ (g)–(h) modes. The superimposed solid curves represent the projections on the three-dimensional-fit PDFs on the respective axis, and the dashed line is the fitted signal contribution. Because these are projections of multiparameter fits, the statistical significance of signal cannot be adduced directly and is generally greater than it appears in the figure. Note that the excess of events on the left of the signal peak in (g) corresponds to the $B^{+}\to p\overline{p}{K}^{+}$ final states, where $K^{+}$ is misidentified as ${\pi }^{+}$. The following loose selection is applied: (a) $m_{\mathrm{ES}}>5.275\mathrm{GeV}/c^2$ and $\mathcal{F}>0.2$; (b) $|\Delta E|<0.02\mathrm{GeV}/c^2$ and $\mathcal{F}>0.2$; (c) $m_{\mathrm{ES}}>5.275\mathrm{GeV}/c^2$ and $\mathcal{F}>0.2$; (d) $|\Delta E|<0.02\mathrm{GeV}/c^2$ and $\mathcal{F}>0.2$; (e) $m_{\mathrm{ES}}>5.275\mathrm{GeV}/c^2$ and $\mathcal{F}>0.6$; (f) $|\Delta E|<0.015\mathrm{GeV}/c^2$ and $\mathcal{F}>0.6$; (g) $m_{\mathrm{ES}}>5.275\mathrm{GeV}/c^2$ and $\mathcal{F}>1.5$; (h) $|\Delta E|<0.015\mathrm{GeV}/c^2$ and $\mathcal{F}>1.5$.

Figure 2

Distribution of $m_{p\overline{p}}$ (points with error bars) for data candidates passing $m_{\mathrm{ES}}>5.27\mathrm{GeV}/c^2$ and $|\Delta E|<0.03\mathrm{GeV}$ selection in the $B^{+}\to p\overline{p}{K}^{*+}$ mode. The solid line represents the projection of the four-dimensional-fit PDFs on the respective axis and the dashed line shows the fitted ${\eta }_c$ contribution. Because this is a projection of the multiparameter fit, the statistical significance of signal cannot be adduced directly and is generally greater than it appears in the figure.

Figure 3

Dalitz plots for signal in the (a) $B^0\to p\overline{p}{K}^0$, (b) $B^{+}\to p\overline{p}{\pi }^{+}$, (c) $B^0\to p\overline{p}{K}^{*0}$, and (d) $B^{+}\to p\overline{p}{K}^{*+}$ modes obtained using the weighting technique described in Ref. [25]. The positions of the following resonances are shown: ${\eta }_c$ in solid, $J/\psi$ in dashed, and ${\mathit{\Lambda }}_c$ in dot-dashed lines. Note, that because of fluctuations and uncertainties, the signal rate in many bins is negative. The white areas correspond to regions with no entries.

Figure 4

Dalitz plots for background in the (a) $B^0\to p\overline{p}{K}^0$, (b) $B^{+}\to p\overline{p}{\pi }^{+}$, (c) $B^0\to p\overline{p}{K}^{*0}$, and (d) $B^{+}\to p\overline{p}{K}^{*+}$ modes obtained using the weighting technique described in Ref. [25]. The expected positions of the following resonances are shown: ${\eta }_c$ in solid, $J/\psi$ in dashed, and ${\mathit{\Lambda }}_c$ in dot-dashed lines. The white areas correspond to regions with no entries.

Figure 5

$m_{p\overline{p}}$ distribution in data (points) for (a) $B^0\to p\overline{p}{K}^0$, (b) $B^{+}\to p\overline{p}{\pi }^{+}$, (c) $B^0\to p\overline{p}{K}^{*0}$, and (d) $B^{+}\to p\overline{p}{K}^{*+}$ modes obtained using the weighting technique described in Ref. [25]. The inner error bars show statistical uncertainty and the outer ones show statistical and systematic uncertainties added in quadrature. The histograms correspond to the relevant three-body phase-space signal Monte Carlo distributions. The dashed line shows zero. The bin size is varying and is specified in Table 10. Note that the contribution from the $B$ decays to charmonium is removed.

Figure 6

$m_{ph}$ distribution obtained using the weighting technique described in Ref. [25]: in red (open circles) for $m_{ph}>m_{\overline{p}h}$ and in black (filled circles) for $m_{ph}<m_{\overline{p}h}$ for (a) $B^0\to p\overline{p}{K}^0$, (b) $B^{+}\to p\overline{p}{\pi }^{+}$, (c) $B^0\to p\overline{p}{K}^{*0}$, and (d) $B^{+}\to p\overline{p}{K}^{*+}$. Solid line shows zero. Only statistical error bars are shown.