Anomalous attenuation of plasmons in strange metals and holography

Abstract

The plasmon is a ubiquitous collective mode in charged liquids. Due to the long-range Coulomb interaction, this mode is gapped and lives infinitely long at long wavelengths in Fermi liquids when the system is translationally invariant. In contrast, the authors show that in strongly entangled strange metals plasmons are always short lived, regardless of their wavelength, and decay into a quantum critical continuum, which replaces Landau damping at any wavelength.