Boson-fermion model beyond mean-field approximation
arXiv:cond-mat/9603111 · doi:10.1088/0953-8984/8/37/014
Abstract
A model of hybridized bosons and fermions is studied beyond the mean field approximation. The divergent boson self-energy at zero temperature makes the Cooper pairing of fermions impossible.The frequency and momentum dependence of the self- energy and the condensation temperature of initially localized bosons are calculated analytically. The value of the boson condensation temperature is below which rules out the boson-fermion model with the initially localized bosons as a phenomenological explanation of high-temperature superconductivity. The intra-cell density-density fermion-boson interaction dominates in the fermion self-energy. The model represents a normal metal with strongly damped bosonic excitations. The latter play the role of normal impurities.
16 pages, Latex, 5 figures available upon request