Quantum dynamics in symmetry-breaking ordered phases of correlated fermions (2410.06831v2)

Abstract: Symmetry-breaking phases of many-fermion systems are characterized by anomalous functions representing transient processes during which some characteristics of free particles, such as spin or charge, are not conserved. Matching the low-temperature symmetry-breaking phase with the high-temperature one consistently with nontrivial quantum dynamics is a long-standing, unresolved problem. We argue that the two-particle propagators may contain only even powers of the anomalous Green functions to make the thermodynamic system conserving. Only then can we continuously match the symmetry-breaking phase with the normal one at the single transition point. We use the antiferromagnetic phase of a dynamical mean-field approximation to disclose universal features of the impact of quantum dynamics on the thermodynamic and spectral properties of the ordered state.