2021/11/10 by Johan Carlström, Carlström, Johan
Physics and Astronomy · #Physics of Superconductivity and Magnetism #Cold Atom Physics and Bose-Einstein Condensates #Advanced Condensed Matter Physics
paper · pdf · doi:10.48550/arxiv.2111.05877
We present a development of strong-coupling diagrammatic techniques which relies on integrating out mean-field-like paths prior to conducting the expansion. This makes it possible to expand around a state with a quasiparticle spectrum that takes into account all kinetic effects that do not explicitly depend on nonlocal correlations. These paths contribute most of the kinetic energy in correlated systems, and so this protocol provides a starting point for the expansion that more closely resembles the full theory. Comparisons to existing exact results clearly confirm this.