Work

Evidence of a New Excited Charmed Baryon Decaying to Σc(2455)0,++π±

Year: 2023

Type: article

Abstract: We present the study of ${\overline{B}}^{0}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Sigma}}}_{c}(2455{)}^{0,++}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}\overline{p}$ decays based on $772\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }B\overline{B}$ events collected with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. The ${\mathrm{\ensuremath{\Sigma}}}_{c}(2455{)}^{0,++}$ candidates are reconstructed via their decay to ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}{\ensuremath{\pi}}^{\ensuremath{\mp}}$ and ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}$ decays to $p{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$, $p{K}_{S}^{0}$, and $\mathrm{\ensuremath{\Lambda}}{\ensuremath{\pi}}^{+}$ final states. The corresponding branching fractions are measured to be $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Sigma}}}_{c}(2455{)}^{0}{\ensuremath{\pi}}^{+}\overline{p})=(1.09\ifmmode\pm\else\textpm\fi{}0.06\ifmmode\pm\else\textpm\fi{}0.07)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Sigma}}}_{c}(2455{)}^{++}{\ensuremath{\pi}}^{\ensuremath{-}}\overline{p})=(1.84\ifmmode\pm\else\textpm\fi{}0.11\ifmmode\pm\else\textpm\fi{}0.12)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$, which are consistent with the world average values with improved precision. A new structure is found in the ${M}_{{\mathrm{\ensuremath{\Sigma}}}_{c}(2455{)}^{0,++}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}}$ spectrum with a significance of $4.2\ensuremath{\sigma}$ including systematic uncertainty. The structure is possibly an excited ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}$ and is tentatively named ${\mathrm{\ensuremath{\Lambda}}}_{c}(2910{)}^{+}$. Its mass and width are measured to be $(2913.8\ifmmode\pm\else\textpm\fi{}5.6\ifmmode\pm\else\textpm\fi{}3.8)\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ and $(51.8\ifmmode\pm\else\textpm\fi{}20.0\ifmmode\pm\else\textpm\fi{}18.8)\text{ }\text{ }\mathrm{MeV}$, respectively. The products of branching fractions for the ${\mathrm{\ensuremath{\Lambda}}}_{c}(2910{)}^{+}$ are measured to be $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Lambda}}}_{c}(2910{)}^{+}\overline{p})\ifmmode\times\else\texttimes\fi{}\mathcal{B}({\mathrm{\ensuremath{\Lambda}}}_{c}(2910{)}^{+}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Sigma}}}_{c}(2455{)}^{0}{\ensuremath{\pi}}^{+})=(9.5\ifmmode\pm\else\textpm\fi{}3.6\ifmmode\pm\else\textpm\fi{}1.6)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ and $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Lambda}}}_{c}(2910{)}^{+}\overline{p})\ifmmode\times\else\texttimes\fi{}\mathcal{B}({\mathrm{\ensuremath{\Lambda}}}_{c}(2910{)}^{+}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Sigma}}}_{c}(2455{)}^{++}{\ensuremath{\pi}}^{\ensuremath{-}})=(1.24\ifmmode\pm\else\textpm\fi{}0.35\ifmmode\pm\else\textpm\fi{}0.10)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$. Here, the first and second uncertainties are statistical and systematic, respectively.

Source: Physical Review Letters

DOI: 10.1103/physrevlett.130.031901