2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/136887We discuss the validity (or not) of the ring-diagram approximation (i.e. RPA) in the calculation of graphene self-energy in the weak-coupling ($r_s \ll 1$) limit, showing that RPA is a controlled and valid approximation for \textit{extrinsic} graphene where the Fermi level is away from the Dirac point.updated with additional paragraph and referenceMaterials ScienceMesoscale and Nanoscale Physicstext