1,804 research outputs found

    Fermion theories on a 2d torus with Wilson action improved by Pauli -- Villars regularization

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    Vectorial and anomaly free chiral U(1) fermion models on a 2d finite lattice are considered. It is demonstrated both numerically and analytically that introduction of Pauli -- Villars type regularization supresses the symmetry breaking effects caused by the Wilson term.Comment: 17 pages, Latex, 6 eps-figure

    Thermodynamic properties of Fermi systems with flat single-particle spectra

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    The behavior of strongly correlated Fermi systems is investigated beyond the onset of a phase transition where the single-particle spectrum ξ(p)\xi({\bf p}) becomes flat. The Landau-Migdal quasiparticle picture is shown to remain applicable on the ordered side of this transition. Nevertheless, low-temperature properties evaluated within this picture show profound changes relative to results of Landau theory, as a direct consequence of the flattening of ξ(p)\xi({\bf p}). Stability conditions for this class of systems are examined, and the nature of antiferromagnetic quantum phase transitions is elucidated.Comment: 5 pages, 5 figure
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