Effective Mass of Positrons in Metals

Abstract

The self-energy of a positron in an electron gas due to electron-positron correlations is calculated to the lowest order in the dynamically screened interaction. It is shown that the dressed positron quasiparticle can be described by an effective mass, but that the calculated effective mass is much too small to account for that measured by observing thermal effects in positron-annihilation experiments. Corrections due to more complicated self-energy processes and to electron-exchange interactions are estimated and found to be small.