Dynamical Symmetry Enlargement versus Spin-Charge Decoupling in the One-Dimensional SU(4) Hubbard Model

Abstract

We investigate dynamical symmetry enlargement in the half-filled SU(4) Hubbard chain using nonperturbative renormalization-group and quantum Monte Carlo techniques. A spectral gap is shown to open for arbitrary Coulombic repulsion $U$. At weak coupling, $U\ensuremath{\lesssim}3t$, a SO(8) symmetry between charge and spin-orbital excitations is found to be dynamically enlarged at low energy whereas at strong coupling, $U\ensuremath{\gtrsim}6t$, the charge degrees of freedom dynamically decouple. The crossover between these regimes is discussed.