9 research outputs found
Kosterlitz-Thouless Transition Line for the Two Dimensional Coulomb Gas
With a rigorous renormalization group approach, we study the pressure of the
two dimensional Coulomb Gas along a small piece of the Kosterlitz-Thouless
transition line, i.e. the boundary of the dipole region in the
activity-temperature phase-space.Comment: 61 pages, 2 figure
Oriented Percolation in One-Dimensional 1/|x-y|^2 Percolation Models
We consider independent edge percolation models on Z, with edge occupation
probabilities p_ = p if |x-y| = 1, 1 - exp{- beta / |x-y|^2} otherwise. We
prove that oriented percolation occurs when beta > 1 provided p is chosen
sufficiently close to 1, answering a question posed in [Commun. Math. Phys.
104, 547 (1986)]. The proof is based on multi-scale analysis.Comment: 19 pages, 2 figures. See also Commentary on J. Stat. Phys. 150,
804-805 (2013), DOI 10.1007/s10955-013-0702-
Gap generation in the BCS model with finite range temporal interaction
In the [BCS] paper the theory of superconductivity was developed for the BCS
model, in which the (instantaneous) interaction is only between fermions of
opposite momentum and spin. Such model was analyzed by variational methods,
finding that a superconducting behavior is energetically favorable.
Subsequently it was claimed that in the thermodynamic limit the BCS model is
equivalent to the (exactly solvable) quadratic mean field BCS model; a rigorous
proof of this claim is however still lacking. In this paper we consider the BCS
model with a finite range temporal interaction, and we prove rigorously its
equivalence with the mean field BCS model in the thermodinamic limit if the
range is long enough, by a (uniformly convergent) perturbation expansion about
mean field theory.Comment: 14 page