Self-consistent linear response approximation for quantum many-body systems

The self-consistent linear response approximation (SCLRA) previously proposed to derive the dispersion of the transverse plasmon in a two-dimensional electron gas [Physica A 127 (1984) 529] is extended to general two-body interactions including the Coulomb interaction. The validity of the conventional ring-diagram approximation is clarified within the framework of the SCLRA.