arXiv subjects

Alexander Moroz

Publications and source records attributed to Alexander Moroz.

57 records · Page 4Linked to original sources

arXiv1992

Quantum Field Theory as a Problem of Resummation (Short guide to using summability methods)

Thesis includes review on the large order behaviour of perturbation theory in quantum mechanical and field theory models; generalization of the Borel summability and strong asymptotic conditions to various (including horn-shaped) regions; discussion of analytic aspects of perturbation theory; examples which demonstrate differences between the Borel summability and generalized one; application to the Rayleigh-Schrödinger perturbation theory and to the definition of the operator valued functions. The new summability methods converges in the whole Mittag-Leffeler star of an analytical function and as such is useful for localization of singularities in the complex plane. Their position can be calculated even analytically provided large order behaviour of the Taylor series is known. Method can be implemented numerically as well.

hep-th↗

arXiv1992

Dimensional Reduction of a Generalized Flux Problem

A generalized flux problem with Abelian and non-Abelian fluxes is considered. In the Abelian case we shall show that the generalized flux problem for tight-binding models of noninteracting electrons on either $2n$ or $2n+1$ dimensional lattice can always be reduced to a $n$ dimensional hopping problem. A residual freedom in this reduction enables to identify equivalence classes of hopping Hamiltonians which have the same spectrum. In the non-Abelian case the reduction is not possible in general unless the flux tensor factorizes into an Abelian one times an element of the corresponding algebra.

cond-mat↗

arXiv1992

Bloch Electron in a Magnetic Field : Diagonalization of Tight-Binding Models

A connection of a variety of tight-binding models of noninteracting electrons on a rectangular lattice in a magnetic field with theta functions is established. A new spectrum generating symmetry is discovered which essentialy reduces the problem of diagonalization of these models. Provided that one knows one eigenvector at one point in the parameter space of the corresponding Harper equation one knows an eigenfunction of the corresponding model in the whole range of momentum singlet out by the Landau gauge.

hep-th↗