Flavor structure of baryons from lattice QCD; From strange to charm quarks

Gubler, P.*; Takahashi, Toru*; Oka, Makoto   

baryons of spin-parity or with either a strange or charm valence quark are studied in full 2+1 flavor lattice QCD. Multiple SU(3) singlet and octet operators are employed to generate the desired single baryon states on the lattice. Via the variational method, the couplings of these states to the different operators provide information about the flavor structure of the Lambda baryons. We make use of the gauge configurations of the PACS-CS collaboration and chirally extrapolate the results for the masses and SU(3) flavor components to the physical point. We furthermore gradually change the hopping parameter of the heaviest quark from strange to charm to study how the properties of the baryons evolve as a function of the heavy quark mass. It is found that the baryon energy levels increase almost linearly with the quark mass. Meanwhile, the flavor structure of most of the states remains stable, with the exception of the lowest state, which changes from a flavor singlet to a state with singlet and octet components of comparable size. Finally, we discuss whether our findings can be interpreted with the help of a simple quark model and find that the negative parity states can be naturally explained as diquark excitations of the light u and d quarks.