2003/07/30 by Paolo Tommasini, E. J. V. de Passos, Tommasini, Paolo +5
Physics and Astronomy · #Advanced Chemical Physics Studies #FOS: Physical sciences #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Soft Condensed Matter (cond-mat.soft) #cond-mat.soft
paper · pdf · doi:10.48550/arxiv.cond-mat/0307745
27 pages, 3 figures
arxiv created 2003/07/30 · openalex publication_date 2003/07/30 · arxiv updated 2009/12/01 · openalex created_date 2022/09/02 · openalex updated_date 2026/07/28
We present a generalization of the Hartree-Fock Bogoliubov (HFB) theory in\nwhich the coupling between one and two quasi-particles is taken into\naccount.This is done by writing the excitation operators as linear combinations\nof one and two HFB quasi-particles. The excitation energies and the\nquasi-particle amplitudes are given by generalized Bogoliubov equations. The\nexcitation spectrum has two branches. The first one is a discrete branch which\nis gapless and has a phonon character at large wave-length and, contrarily to\nHFB, is always stable. This branch is detached from a continuum branch whose\nthreshold, at fixed total momentum, coincides with the two quasi-particle\nthreshold of the HFB theory. The gap between these two branches at P=0 is equal\nto two times the HFB gap, which then provides for the relevant energy scale. We\nalso give numerical results for a specific case.\n