Quantum Electrodynamics of Non-Hermitian Dirac Fermions.

This talk provides an effective quantum electrodynamics for non-Hermitian (NH) Dirac materials interacting with photons. These systems are described by Lorentz invariant NH Dirac operators, featuring two velocity parameters v_H and v_NH associated with the standard Hermitian and a masslike antiHermitian Dirac operators, respectively. They display linear energy-momentum relation, however, in terms of an effective Fermi velocity v_F=(v²_H-v²_NH)^1/2 of NH Dirac fermions. Interaction with the fluctuating electromagnetic radiation then gives birth to an emergent Lorentz symmetry in this family of NH Dirac materials in the deep infrared regime, where the system possesses a unique terminal velocity v_F=c, with c being the speed of light. While in two dimensions such a terminal velocity is set by the speed of light in the free space, dynamic screening in three spatial dimensions permits its nonuniversal values. Manifestations of such an emergent spacetime symmetry on the scale dependence of various physical observables in correlated NH Dirac materials are discussed.