The general presence of exceptional points induced by Fermi-surface instability

We present the discovery of exceptional points (EPs) arising from order parameter fluctuations during the formation of long-range order. These EPs lead to the emergence of degenerate arcs in the energy bands. These arcs, which are essentially the branch cuts of the Riemann surface representing the band structure near the EPs, may be observed in spectroscopic experiments. Our results indicate that the formation of EPs may be a universal feature in the process of spontaneous symmetry breaking.