Single-particle excitations in the uniform electron gas by diagrammatic Monte Carlo

We calculate the single-particle excitation spectrum and the Landau Fermi liquid parameters for the archetypal model of solids, the three-dimensional uniform electron gas, with the numerically exact variational diagrammatic Monte Carlo method. In the metallic range of density, we establish benchmark values for the wave-function renormalization factor $Z$, the effective mass $m^*/m$, and the Landau parameters $F_0^s$ and $F_0^a$ with unprecedented accuracy, and we resolve the long-standing puzzle of non-monotonic dependence of mass on density. We also exclude the possibility that experimentally measured large reduction of bandwidth in Na metal can originate from the charge and spin fluctuations contained in the model of the uniform electron gas.