Extended States for the Schrödinger Operator with Quasi-Periodic Potential in Dimension Two
Extended States for the Schrödinger Operator with Quasi-Periodic Potential in Dimension Two

Author: Yulia Karpeshina

Publisher: American Mathematical Soc.

Published: 2019-04-10

Total Pages: 152

ISBN-13: 1470435438

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The authors consider a Schrödinger operator H=−Δ+V(x⃗ ) in dimension two with a quasi-periodic potential V(x⃗ ). They prove that the absolutely continuous spectrum of H contains a semiaxis and there is a family of generalized eigenfunctions at every point of this semiaxis with the following properties. First, the eigenfunctions are close to plane waves ei⟨ϰ⃗ ,x⃗ ⟩ in the high energy region. Second, the isoenergetic curves in the space of momenta ϰ⃗ corresponding to these eigenfunctions have the form of slightly distorted circles with holes (Cantor type structure). A new method of multiscale analysis in the momentum space is developed to prove these results. The result is based on a previous paper on the quasiperiodic polyharmonic operator (−Δ)l+V(x⃗ ), l>1. Here the authors address technical complications arising in the case l=1. However, this text is self-contained and can be read without familiarity with the previous paper.

Dimensions of Affine Deligne–Lusztig Varieties: A New Approach Via Labeled Folded Alcove Walks and Root Operators
Dimensions of Affine Deligne–Lusztig Varieties: A New Approach Via Labeled Folded Alcove Walks and Root Operators

Author: Elizabeth Milićević

Publisher: American Mathematical Soc.

Published: 2019-12-02

Total Pages: 114

ISBN-13: 1470436760

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Let G be a reductive group over the field F=k((t)), where k is an algebraic closure of a finite field, and let W be the (extended) affine Weyl group of G. The associated affine Deligne–Lusztig varieties Xx(b), which are indexed by elements b∈G(F) and x∈W, were introduced by Rapoport. Basic questions about the varieties Xx(b) which have remained largely open include when they are nonempty, and if nonempty, their dimension. The authors use techniques inspired by geometric group theory and combinatorial representation theory to address these questions in the case that b is a pure translation, and so prove much of a sharpened version of a conjecture of Görtz, Haines, Kottwitz, and Reuman. The authors' approach is constructive and type-free, sheds new light on the reasons for existing results in the case that b is basic, and reveals new patterns. Since they work only in the standard apartment of the building for G(F), their results also hold in the p-adic context, where they formulate a definition of the dimension of a p-adic Deligne–Lusztig set. The authors present two immediate applications of their main results, to class polynomials of affine Hecke algebras and to affine reflection length.

Compact Quotients of Cahen-Wallach Spaces
Compact Quotients of Cahen-Wallach Spaces

Author: Ines Kath

Publisher: American Mathematical Soc.

Published: 2020-02-13

Total Pages: 96

ISBN-13: 1470441039

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Indecomposable symmetric Lorentzian manifolds of non-constant curvature are called Cahen-Wallach spaces. Their isometry classes are described by continuous families of real parameters. The authors derive necessary and sufficient conditions for the existence of compact quotients of Cahen-Wallach spaces in terms of these parameters.

Green's Function Estimates for Lattice Schrodinger Operators and Applications. (AM-158)
Green's Function Estimates for Lattice Schrodinger Operators and Applications. (AM-158)

Author: Jean Bourgain

Publisher: Princeton University Press

Published: 2005

Total Pages: 183

ISBN-13: 0691120986

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This book presents an overview of recent developments in the area of localization for quasi-periodic lattice Schrödinger operators and the theory of quasi-periodicity in Hamiltonian evolution equations. The physical motivation of these models extends back to the works of Rudolph Peierls and Douglas R. Hofstadter, and the models themselves have been a focus of mathematical research for two decades. Jean Bourgain here sets forth the results and techniques that have been discovered in the last few years. He puts special emphasis on so-called "non-perturbative" methods and the important role of subharmonic function theory and semi-algebraic set methods. He describes various applications to the theory of differential equations and dynamical systems, in particular to the quantum kicked rotor and KAM theory for nonlinear Hamiltonian evolution equations. Intended primarily for graduate students and researchers in the general area of dynamical systems and mathematical physics, the book provides a coherent account of a large body of work that is presently scattered in the literature. It does so in a refreshingly contained manner that seeks to convey the present technological "state of the art."

A Local Relative Trace Formula for the Ginzburg-Rallis Model: The Geometric Side
A Local Relative Trace Formula for the Ginzburg-Rallis Model: The Geometric Side

Author: Chen Wan

Publisher: American Mathematical Soc.

Published: 2019-12-02

Total Pages: 102

ISBN-13: 1470436868

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Following the method developed by Waldspurger and Beuzart-Plessis in their proofs of the local Gan-Gross-Prasad conjecture, the author is able to prove the geometric side of a local relative trace formula for the Ginzburg-Rallis model. Then by applying such formula, the author proves a multiplicity formula of the Ginzburg-Rallis model for the supercuspidal representations. Using that multiplicity formula, the author proves the multiplicity one theorem for the Ginzburg-Rallis model over Vogan packets in the supercuspidal case.

Interacting Stochastic Systems
Interacting Stochastic Systems

Author: Jean-Dominique Deuschel

Publisher: Springer Science & Business Media

Published: 2005-01-12

Total Pages: 470

ISBN-13: 9783540230335

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The Research Network on "Interacting stochastic systems of high complexity" set up by the German Research Foundation aimed at exploring and developing connections between research in infinite-dimensional stochastic analysis, statistical physics, spatial population models from mathematical biology, complex models of financial markets or of stochastic models interacting with other sciences. This book presents a structured collection of papers on the core topics, written at the close of the 6-year programme by the research groups who took part in it. The structure chosen highlights the interweaving of certain themes and certain interconnections discovered through the joint work. This yields a reference work on results and methods that will be useful to all who work between applied probability and the physical, economic, and life sciences.

Schrödinger Operators
Schrödinger Operators

Author: Hans L. Cycon

Publisher: Springer Science & Business Media

Published: 1987

Total Pages: 337

ISBN-13: 3540167587

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Are you looking for a concise summary of the theory of Schrödinger operators? Here it is. Emphasizing the progress made in the last decade by Lieb, Enss, Witten and others, the three authors don’t just cover general properties, but also detail multiparticle quantum mechanics – including bound states of Coulomb systems and scattering theory. This corrected and extended reprint contains updated references as well as notes on the development in the field over the past twenty years.

Multiscale Methods in Quantum Mechanics
Multiscale Methods in Quantum Mechanics

Author: Philippe Blanchard

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 223

ISBN-13: 0817682023

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This volume explores multiscale methods as applied to various areas of physics and to the relative developments in mathematics. In the last few years, multiscale methods have lead to spectacular progress in our understanding of complex physical systems and have stimulated the development of very refined mathematical techniques. At the same time on the experimental side, equally spectacular progress has been made in developing experimental machinery and techniques to test the foundations of quantum mechanics.

Matrix Functions of Bounded Type: An Interplay Between Function Theory and Operator Theory
Matrix Functions of Bounded Type: An Interplay Between Function Theory and Operator Theory

Author: Raúl E. Curto

Publisher: American Mathematical Soc.

Published: 2019-09-05

Total Pages: 112

ISBN-13: 1470436248

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In this paper, the authors study matrix functions of bounded type from the viewpoint of describing an interplay between function theory and operator theory. They first establish a criterion on the coprime-ness of two singular inner functions and obtain several properties of the Douglas-Shapiro-Shields factorizations of matrix functions of bounded type. They propose a new notion of tensored-scalar singularity, and then answer questions on Hankel operators with matrix-valued bounded type symbols. They also examine an interpolation problem related to a certain functional equation on matrix functions of bounded type; this can be seen as an extension of the classical Hermite-Fejér Interpolation Problem for matrix rational functions. The authors then extend the H∞-functional calculus to an H∞¯¯¯¯¯¯¯¯¯+H∞-functional calculus for the compressions of the shift. Next, the authors consider the subnormality of Toeplitz operators with matrix-valued bounded type symbols and, in particular, the matrix-valued version of Halmos's Problem 5 and then establish a matrix-valued version of Abrahamse's Theorem. They also solve a subnormal Toeplitz completion problem of 2×2 partial block Toeplitz matrices. Further, they establish a characterization of hyponormal Toeplitz pairs with matrix-valued bounded type symbols and then derive rank formulae for the self-commutators of hyponormal Toeplitz pairs.