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) x 64, N-f = 2 +/- 1 PACS-CS gauge configurations at the almost physical pion mass of similar to 156 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 Xi(c)-Xi(c)' 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 Sigma(c), Xi(c) and Omega(c) baryons, including some of the Xi(c) states recently reported by LHCb. Our results for the doubly and triply charmed baryons are suggestive for future experiments.