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We prove that the asymptotic distribution of resonances has a multilevel internal structure for the following classes of Hamiltonians H: Schr\"odinger operators with point interactions in $\mathbb{R}^3$, quantum graphs, and 1-D photonic…

Mathematical Physics · Physics 2019-10-08 Sergio Albeverio , Illya M. Karabash

We consider a magnetic laplacian P(A) on the Poincar\'e half-plane, when the magnetic field dA is infinite at infinity such that P(A) has pure discret spectrum. We give the asymptotic behavior of the counting function of the eigenvalues.

Mathematical Physics · Physics 2008-12-17 Abderemane Morame , Francoise Truc

We perform direct numerical simulations of the equations of magnetohydrodynamics with external random forcing and in the presence of gravity. The domain is divided into two parts: a lower layer where the forcing is helical and an upper…

Solar and Stellar Astrophysics · Physics 2014-10-20 Dhrubaditya Mitra , A. Brandenburg , N. Kleeorin , I. Rogachevskii

In this paper we derive formulae for the semiclassical tunneling in the presence of a constant magnetic field in 2 dimensions. The `wells' in the problem are identical discs with Neumann boundary conditions, so we study the magnetic Neumann…

Mathematical Physics · Physics 2024-11-20 Søren Fournais , Léo Morin

A many body Hamiltonian comprising pairing, quadrupole-quadrupole and spin-spin interaction is treated within a projected spherical basis with the aim of describing the detailed structure of the magnetic states of orbital and spin-flip…

Nuclear Theory · Physics 2009-11-07 A. A. Raduta , A. Escuderos , E. Moya de Guerra

We investigate the effects of a nonuniform uniaxial strain and a triaxial strain on the $\alpha-{\cal T}_3$ lattice. The analytical expressions of the pseudo-Landau levels (pLLs) are derived based on low-energy Hamiltonians, and are…

Mesoscale and Nanoscale Physics · Physics 2022-10-21 Junsong Sun , Tianyu Liu , Yi Du , Huaiming Guo

We compute three-term semiclassical asymptotic expansions of counting functions and Riesz-means of the eigenvalues of the Laplacian on spheres and hemispheres, for both Dirichlet and Neumann boundary conditions. Specifically for Riesz-means…

Spectral Theory · Mathematics 2023-03-15 Davide Buoso , Paolo Luzzini , Luigi Provenzano , Joachim Stubbe

Magnetic properties of two and three-dimensional clusters of quantum dots are studied with exact diagonalization of a generalized Hubbard model. We study the weak coupling limit, where the electrons interact only within a quantum dot and…

Strongly Correlated Electrons · Physics 2009-11-13 J. -P. Nikkarila , M. Koskinen , M. Manninen

This paper is devoted to the asymptotic analysis of the optimal Sobolev constants in the semiclassical limit and in any dimension. We combine semiclassical arguments and concentration-compactness estimates to tackle the case when an…

Analysis of PDEs · Mathematics 2018-08-21 Soeren Fournais , Loïc Le Treust , Nicolas Raymond , Jean Van Schaftingen

We consider the single particle relaxation rate of 2D electrons subject to a random magnetic field. The density of states (DOS) oscillations in a uniform magnetic field (in addition to a random one) are studied. We define a gauge invariant…

Condensed Matter · Physics 2007-05-23 E. Altshuler , A. G. Aronov , A. D. Mirlin , P. Woelfle

We consider a relativistic no-pair model of a hydrogenic atom in a classical, exterior magnetic field. First, we prove that the corresponding Hamiltonian is semi-bounded below, for all coupling constants less than or equal to the critical…

Mathematical Physics · Physics 2010-10-11 Oliver Matte , Edgardo Stockmeyer

We study the inflationary generation of helical cosmological magnetic fields in a higher-dimensional generalization of the electromagnetic theory. For this purpose, we also include a parity breaking piece to the electromagnetic action. The…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Kumar Atmjeet , T. R. Seshadri , Kandaswamy Subramanian

We study numerically the Hessian of low-lying minima of vector spin glass models defined on random regular graphs. We consider the two-component (XY) and three-component (Heisenberg) spin glasses at zero temperature, subjected to the action…

Disordered Systems and Neural Networks · Physics 2025-06-03 Silvio Franz , Cosimo Lupo , Flavio Nicoletti , Giorgio Parisi , Federico Ricci-Tersenghi

Azimuthal structures emerging in beam-generated partially magnetized plasmas are investigated using three-dimensional particle-in-cell/Monte Carlo collision simulations. Two distinct instability regimes are identified at low pressures. When…

Plasma Physics · Physics 2025-07-01 Jian Chen , Andrew T. Powis , Igor D. Kaganovich , Zhibin Wang

We consider the Laplacian on a class of smooth domains $\Omega\subset \mathbb{R}^{\nu}$, $\nu\ge 2$, with attractive Robin boundary conditions: \[ Q^\Omega_\alpha u=-\Delta u, \quad \dfrac{\partial u}{\partial n}=\alpha u \text{ on }…

Spectral Theory · Mathematics 2016-08-31 Konstantin Pankrashkin , Nicolas Popoff

We develop a two-scale formalism to determine global magnetic helicity spectra in systems where the local magnetic helicity has opposite signs on both sides of the equator, giving rise to cancelation with conventional methods. We verify…

Solar and Stellar Astrophysics · Physics 2017-02-07 Axel Brandenburg , Gordon J. D. Petrie , Nishant K. Singh

We discuss an exactly solvable model Hamiltonian for describing the interacting electron gas in a quantum dot. Results for a spherical square well confining potential are presented. The ground state is found to exhibit striking oscillations…

Materials Science · Physics 2009-11-10 R. Saniz , B. Barbiellini , A. B. Denison , A. Bansil

We consider the magnetic Laplacian with the homogeneous magnetic field in two and three dimensions. We prove that the $(k+1)$-th magnetic Neumann eigenvalue of a bounded convex planar domain is not larger than its $k$-th magnetic Dirichlet…

Spectral Theory · Mathematics 2024-05-21 Vladimir Lotoreichik

We investigate symmetry properties of the first nontrivial eigenfunctions of the fractional Laplacian $(-\Delta)^s$, where $s \in (0,1)$, in an $N$-dimensional ball with nonlocal Neumann boundary conditions. By means of a spectral stability…

Analysis of PDEs · Mathematics 2026-03-12 Vladimir Bobkov , Enea Parini

The quantum dynamics of an electron in a uniform magnetic field is studied for geometries corresponding to integrable cases. We obtain the uniform asymptotic approximation of the WKB energies and wavefunctions for the semi-infinite plane…

Mesoscale and Nanoscale Physics · Physics 2009-10-30 D. Spehner , R. Narevich , E. Akkermans
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