Study of the charmed baryonic decays ${\overline{B}}^0\to {\Sigma }_c^{++}\overline{p}{\pi }^{-}$ and ${\overline{B}}^0\to {\Sigma }_c^0\overline{p}{\pi }^{+}$

We study the three-body charmed baryonic decays ${\overline{B}}^0\to {\Sigma }_c^{++}\overline{p}{\pi }^{-}$ and ${\overline{B}}^0\to {\Sigma }_c^0\overline{p}{\pi }^{+}$ in the four-body final state ${\overline{B}}^0\to {\Lambda }_c^{+}\overline{p}{\pi }^{+}{\pi }^{-}$, using a data sample of $357{\mathrm{fb}}^{-1}$ accumulated at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We measure the branching fractions $\mathcal{B}({\overline{B}}^0\to {\Sigma }_c(2455{)}^{++}\overline{p}{\pi }^{-})=(2.1\pm 0.2\pm 0.3\pm 0.5)\times {10}^{-4}$, $\mathcal{B}({\overline{B}}^0\to {\Sigma }_c(2455{)}^0\overline{p}{\pi }^{+})=(1.4\pm 0.2\pm 0.2\pm 0.4)\times {10}^{-4}$ and $\mathcal{B}({\overline{B}}^0\to {\Sigma }_c(2520{)}^{++}\overline{p}{\pi }^{-})=(1.2\pm 0.1\pm 0.2\pm 0.3)\times {10}^{-4}$ with signal significances of $13.1\sigma$, $9.4\sigma$ and $7.1\sigma$, respectively. The errors are statistical, systematic, and due to the uncertainty in $\mathcal{B}({\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+})$, respectively. We also set an upper limit $\mathcal{B}({\overline{B}}^0\to {\Sigma }_c(2520{)}^0\overline{p}{\pi }^{+})<0.38\times {10}^{-4}$ at the 90% confidence level. In addition, we obtain a nonresonant branching fraction of $(6.4\pm 0.4\pm 0.9\pm 1.7)\times {10}^{-4}$, and a total branching fraction of $(11.2\pm 0.5\pm 1.4\pm 2.9)\times {10}^{-4}$ for ${\overline{B}}^0\to {\Lambda }_c^{+}\overline{p}{\pi }^{+}{\pi }^{-}$.

Figure 1

(a) Scatter plot of $\Delta E$ vs $M_{\mathrm{bc}}$ for ${\overline{B}}^0\to {\Lambda }_c^{+}\overline{p}{\pi }^{+}{\pi }^{-}$ signal candidates. (b) The $\Delta E$ distribution for $M_{\mathrm{bc}}\ge 5.27\mathrm{GeV}/c^2$. The shaded regions indicate the sideband whose total area is equal to the background in the $B$ signal region. (c) The $M_{\mathrm{bc}}$ distribution for $|\Delta E|\le 0.03\mathrm{GeV}$.

Figure 2

The mass distributions of (a) ${\Lambda }_c^{+}{\pi }^{+}$ and (b) ${\Lambda }_c^{+}{\pi }^{-}$ for ${\overline{B}}^0\to {\Lambda }_c^{+}\overline{p}{\pi }^{+}{\pi }^{-}$. The points with error bars show the mass distribution for the events in the $B$ signal region, and the shaded histogram indicates that for the sideband region. See the text for details.