Renormalized SO(5) symmetry in ladders with next-nearest-neighbor hopping

TL;DR

This paper demonstrates that SO(5) symmetry is asymptotically restored at low energies in two-chain Hubbard systems, even with next-nearest-neighbor hopping that breaks particle-hole symmetry, through renormalization group analysis.

Contribution

It shows that SO(5) symmetry emerges at low energies in two-chain Hubbard models, despite explicit symmetry-breaking terms, using renormalization group flow analysis.

Findings

SO(5) symmetry is asymptotically restored at low energies.

Next-nearest-neighbor hopping does not prevent symmetry restoration.

Renormalized SO(5) symmetry has physical significance.

Abstract

We study the occurrence of SO(5) symmetry in the low-energy sector of two-chain Hubbard-like systems by analyzing the flow of the running couplings ($g$-ology) under renormalization group in the weak-interaction limit. It is shown that SO(5) is asymptotically restored for low energies for rather general parameters of the bare Hamiltonian. This holds also with inclusion of a next-nearest-neighbor hopping which explicitly breaks particle-hole symmetry provided one accounts for a different single-particle weight for the quasiparticles of the two bands of the system. The physical significance of this renormalized SO(5) symmetry is discussed.