Charmed baryon spectrum from lattice QCD near the physical point

Abstract

We calculate the low-lying spectrum of charmed baryons in lattice QCD on the ${32}^{3}\ifmmode\times\else\texttimes\fi{}64$, ${N}_{f}=2+1$ PACS-CS gauge configurations at the almost physical pion mass of $\ensuremath{\sim}156\text{ }\text{ }\mathrm{MeV}/{c}^{2}$. By employing a set of interpolating operators with different Dirac structures and quark-field smearings for the variational analysis, we extract the ground and first few excited states of the spin-$1/2$ and spin-$3/2$, singly, doubly, and triply charmed baryons. Additionally, we study the ${\mathrm{\ensuremath{\Xi}}}_{c}\text{\ensuremath{-}}{\mathrm{\ensuremath{\Xi}}}_{c}^{\ensuremath{'}}$ mixing and the operator dependence of the excited states in a variational approach. We identify several states that lie close to the experimentally observed excited states of the ${\mathrm{\ensuremath{\Sigma}}}_{c}$, ${\mathrm{\ensuremath{\Xi}}}_{c}$ and ${\mathrm{\ensuremath{\Omega}}}_{c}$ baryons, including some of the ${\mathrm{\ensuremath{\Xi}}}_{c}$ states recently reported by LHCb. Our results for the doubly and triply charmed baryons are suggestive for future experiments.