Observation of the baryonic decay ${\overline{B}}^0\to {\mathrm{\Lambda }}_c^{+}\overline{p}{K}^{-}{K}^{+}$

We report the observation of the baryonic decay ${\overline{B}}^0\to {\mathrm{\Lambda }}_c^{+}\overline{p}{K}^{-}{K}^{+}$ using a data sample of $471\times 10^6$ $B\overline{B}$ pairs produced in $e^{+}{e}^{-}$ annihilations at $\sqrt{s}=10.58\mathrm{GeV}$. This data sample was recorded with the BABAR detector at the PEP-II storage ring at SLAC. We find $\mathcal{B}({\overline{B}}^0\to {\mathrm{\Lambda }}_c^{+}\overline{p}{K}^{-}{K}^{+})=(2.5\pm 0.4_{(\text{stat})}\pm 0.2_{(\text{syst})}\pm 0.6_{\mathcal{B}({\mathrm{\Lambda }}_c^{+})})\times 10^{-5}$, where the uncertainties are statistical, systematic, and due to the uncertainty of the ${\mathrm{\Lambda }}_c^{+}\to p{K}^{-}{\pi }^{+}$ branching fraction, respectively. The result has a significance corresponding to 5.0 standard deviations, including all uncertainties. For the resonant decay ${\overline{B}}^0\to {\mathrm{\Lambda }}_c^{+}\overline{p}\varphi$, we determine the upper limit $\mathcal{B}({\overline{B}}^0\to {\mathrm{\Lambda }}_c^{+}\overline{p}\varphi )<1.2\times 10^{-5}$ at 90% confidence level.

Figure 1

The $m_B$ vs $m_{\mathrm{ES}}$ distribution for correctly reconstructed simulated signal events.

Figure 2

Data (points with statistical uncertainties) and projections of the maximum likelihood fit (solid curves) for ${\overline{B}}^0\to {\mathrm{\Lambda }}_c^{+}\overline{p}{K}^{-}{K}^{+}$ candidates. The dashed curves show the projections of the PDF for background events. (a) Results for $m_{\mathrm{ES}}$, with the requirement $5.26\mathrm{GeV}/c^2\le m_B\le 5.30\mathrm{GeV}/c^2$. (b) Results for $m_B$, with the requirement $5.275\mathrm{GeV}/c^2\le m_{\mathrm{ES}}\le 5.285\mathrm{GeV}/c^2$.

Figure 3

(a) Baryon-antibaryon invariant mass signal distribution and (b) kaon-kaon invariant mass signal distribution for data (points with statistical uncertainties) compared to distributions for simulated ${\overline{B}}^0\to {\mathrm{\Lambda }}_c^{+}\overline{p}{K}^{-}{K}^{+}$ decays generated according to four-body phase space (shaded histogram), scaled to the same number of events as in data. Regions I, II, and III are indicated in the figure and described in the text.