Role of electron-hole interactions in the optical spectra of metals

It was recently argued that, contrary to what has been universally believed, single-particle theory is not adequate to describe the optical spectra of metals and that electron-hole (excitonic) effects play a dominant role. Here, we present theoretical calculations using two different conceptual frameworks which indicate that the opposite is in fact true. We also identify the inappropriate approximations that exaggerated the role of excitonic effects and conclude that the latter play only a minimal role in the optical spectra of metals.