Emergence of a new $SU(4)$ symmetry in the baryon spectrum

Emergence of a new $S U (4)$ symmetry in the baryon spectrum

M. Denissenya, L. Ya. Glozman, and M. Pak

Phys. Rev. D 92, 074508 – Published 23 October 2015; Erratum Phys. Rev. D 92, 099902 (2015)

Abstract

Recently, a large degeneracy of $J = 1$ mesons—that is, larger than the $S U (2)_{L} \times S U (2)_{R} \times U (1)_{A}$ symmetry of the QCD Lagrangian—has been discovered upon truncation of the near-zero modes from the valence quark propagators. It has been found that this degeneracy represents the $S U (4)$ group that includes the chiral rotations as well as the mixing of left- and right-handed quarks. This symmetry group turns out to be a symmetry of confinement in QCD. Consequently, one expects that the same symmetry should persist upon the near-zero mode removal in other hadron sectors as well. It has been shown that indeed the $J = 2$ mesons follow the same symmetry pattern upon the low-lying mode elimination. Here we demonstrate the $S U (4)$ symmetry of baryons once the near-zero modes are removed from the quark propagators. We also show a degeneracy of states belonging to different irreducible representations of $S U (4)$ . This implies a larger symmetry that includes $S U (4)$ as a subgroup.