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We compute the spectral density for ensembles of of sparse symmetric random matrices using replica, managing to circumvent difficulties that have been encountered in earlier approaches along the lines first suggested in a seminal paper by…

Disordered Systems and Neural Networks · Physics 2009-11-13 Reimer Kuehn

Implicit particle filters for data assimilation generate high-probability samples by representing each particle location as a separate function of a common reference variable. This representation requires that a certain underdetermined…

Numerical Analysis · Mathematics 2015-05-27 Matthias Morzfeld , Xuemin Tu , Ethan Atkins , Alexandre J. Chorin

We greatly simplify the light-cone gauge description of a relativistic membrane moving in Minkowski space by performing a field-dependent change of variables which allows the explicit solution of all constraints and a Hamiltonian reduction…

High Energy Physics - Theory · Physics 2011-05-05 Martin Bordemann , Jens Hoppe

For minimization problems without 2nd derivative information, methods that estimate Hessian matrices can be very effective. However, conventional techniques generate dense matrices that are prohibitive for large problems. Limited-memory…

Optimization and Control · Mathematics 2025-01-22 Johannes J. Brust

In this work, we show that extending the standard description of space-time symmetries from groups of isometries to the more flexible framework of kinematical groupoids allows for the extension of Wigner's program to curved space-times. We…

Mathematical Physics · Physics 2026-04-08 Alberto Ibort , Giuseppe Marmo , Arnau Mas , Luca Schiavone

Wigner's quantum-mechanical classification of particle-types in terms of irreducible representations of the Poincar\'e group has a classical analogue, which we extend in this paper. We study the compactness properties of the resulting phase…

Classical Physics · Physics 2023-07-28 Jacob A. Barandes

We propose a framework for the free field construction of algebras of local observables which uses as an input the Bisognano-Wichmann relations and a representation of the Poincare' group on the one-particle Hilbert space. The abstract real…

Mathematical Physics · Physics 2011-04-06 Romeo Brunetti , Daniele Guido , Roberto Longo

The conventional Wigner function is inappropriate in a quantum field theory setting because, as a quasiprobability density over phase space, it is not manifestly Lorentz covariant. A manifestly relativistic variant is constructed as a…

Quantum Physics · Physics 2007-05-23 Peter Morgan

The classification of elementary particles based on unitary irreducible representations of the Poincare group has been a cornerstone of modern Quantum Field Theory (QFT). While the Standard Model (SM) does not inherently include Dark Matter…

High Energy Physics - Phenomenology · Physics 2025-06-16 Cheng-Yang Lee , Ruifeng Leng , Siyi Zhou

We provide an alternative approach to relativistic dynamics based on the Feshbach projection technique. Instead of directly studying the Dirac equation, we derive a two-component equation for the upper spinor. This approach allows one to…

Quantum Physics · Physics 2016-10-21 Da-Wei Luo , P. V. Pyshkin , Ting Yu , Hai-Qing Lin , J. Q. You , Lian-Ao Wu

Models, describing relativistic particles, where Lagrangian densities depend linearly on both the curvature and the torsion of the trajectories, are revisited in D=3 space forms. The moduli spaces of trajectories are completely and…

High Energy Physics - Theory · Physics 2009-11-10 Josu Arroyo , Manuel Barros , Oscar J. Garay

The variational reduced density matrix theory has been recently applied with great success to models within the truncated doubly-occupied configuration interaction space, which corresponds to the seniority zero subspace. Conservation of the…

Strongly Correlated Electrons · Physics 2018-07-26 A. Rubio-Garcia , D. R. Alcoba , P. Capuzzi , J. Dukelsky

This paper develops the theory of Dirac reduction by symmetry for nonholonomic systems on Lie groups with broken symmetry. The reduction is carried out for the Dirac structures, as well as for the associated Lagrange-Dirac and…

Symplectic Geometry · Mathematics 2014-10-21 François Gay-Balmaz , Hiroaki Yoshimura

Compressive Sensing theory says that it is possible to reconstruct a measured signal if an enough sparse representation of this signal exists in comparison to the number of random measurements. This theory was applied to reconstruct signals…

In this review, we have reached from the most basic definitions in the theory of groups, group structures, etc. to representation theory and irreducible representations of the Poincar'e group. Also, we tried to get a more comprehensible…

Group Theory · Mathematics 2024-09-04 Meysam Hassandoust

Covariantly we reformulate the description of a spinning particle in terms of the Poincar\'{e} group. We also construct a Lagrangian which entails all possible constraints explicitly; all constraints can be obtained just from the…

High Energy Physics - Theory · Physics 2009-10-28 Jin-Ho Cho , Seungjoon Hyun , Jae-Kwan Kim

We construct a Lagrangian description of irreducible integer higher-spin representations of the Poincare group with an arbitrary Young tableaux having k rows, on a basis of the universal BRST approach. Starting with a description of bosonic…

High Energy Physics - Theory · Physics 2025-02-18 I. L. Buchbinder , A. Reshetnyak

The Wigner function for one and two-mode quantum systems is explicitely expressed in terms of the marginal distribution for the generic linearly transformed quadratures. Then, also the density operator of those systems is written in terms…

Quantum Physics · Physics 2009-10-30 G. M. D'Ariano , S. Mancini , V. I. Man'ko , P. Tombesi

We study representations of the Poincar\'e group that have a privileged transformation law along a p-dimensional hyperplane, and uncover their associated spinor helicity variables in D spacetime dimensions. Our novel representations…

High Energy Physics - Theory · Physics 2022-12-20 Csaba Csaki , Ofri Telem , John Terning

A group theoretical understanding of the two dimensional fractional supersymmetry is given in terms of the quantum Poincare group at roots of unity. The fractional supersymmetry algebra and the quantum group dual to it are presented and the…

Quantum Algebra · Mathematics 2008-11-26 H. Ahmedov , O. F. Dayi