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We propose a formally exact statistical field theory for describing classical fluids with ingredients similar to those introduced in quantum field theory. We consider the following essential and related problems : i) how to find the correct…

Soft Condensed Matter · Physics 2008-11-26 D. di Caprio , J. P. Badiali

The quantum dynamics of fermionic or bosonic many-body systems following external excitation can be successfully studied using two-time nonequilibrium Green's functions (NEGF) or single-time reduced density matrix methods. Approximations…

Strongly Correlated Electrons · Physics 2022-07-12 Erik Schroedter , Jan-Philip Joost , Michael Bonitz

We perform a perturbative analysis for the nonequilibrium Green functions of the spinless Falicov-Kimball model in the presence of an arbitrary external time-dependent but spatially uniform electric field. The conduction electron…

Strongly Correlated Electrons · Physics 2009-11-11 V. Turkowski , J. K. Freericks

An approximate procedure for performing nonperturbative calculations in quantum field theories is presented. The focus will be quantum non-Abelian gauge theories with the goal of understanding some of the open questions of these theories…

High Energy Physics - Phenomenology · Physics 2007-05-23 V. Dzhunushaliev , D. Singleton , T. Nikulicheva

A single-time quantum transport equation, which includes effects beyond the quasiparticle approximation, is derived for Fermi-systems in the framework of non-equilibrium real-time Green's functions theory. Ternary correlations are…

Nuclear Theory · Physics 2009-10-30 A. Sedrakian , G. Roepke

We introduce a fundamental theory for the kinetics of systems of classical particles. The theory represents a unification of kinetic theory, Brownian motion and field theory. It is self-consistent and is the dynamic generalization of the…

Statistical Mechanics · Physics 2010-06-14 Gene F. Mazenko

A general semiclassical approach to quantum systems with system-bath interactions is developed. We study system decoherence in detail using a coherent state semiclassical wavepacket method which avoids singularity issues arising in the…

Quantum Physics · Physics 2009-11-07 Gregory A. Fiete , Eric J. Heller

We consider some non-linear non-homogeneous partial differential equations (PDEs) and derive their exact Green function solution as a functional Taylor expansion in powers of the source. The kind of PDEs we consider are dispersive ones…

Mathematical Physics · Physics 2024-11-12 Marco Frasca , Stefan Groote

The many-body theory of degenerate systems is described in detail. More generally, this theory applies to systems with an initial state that cannot be described by a single Slater determinant. The double-source (or closed-time-path)…

Strongly Correlated Electrons · Physics 2007-05-23 Christian Brouder

We derive a general expression for the electron nonequilibrium (NE) distribution function in the context of steady state quantum transport through a two-terminal nanodevice with interaction. The central idea for the use of NE distributions…

Mesoscale and Nanoscale Physics · Physics 2014-02-26 H. Ness

We consider a general class of approximations which guarantees the conservation of particle number in many-body perturbation theory. To do this we extend the concept of $\Phi$-derivability for the self-energy $\Sigma$ to a larger class of…

Strongly Correlated Electrons · Physics 2016-09-15 Daniel Karlsson , Robert van Leeuwen

A non-Abelian theory of fermions interacting with gauge bosons, the constrained system, is studied. The equations of motion for a singular system are obtained as total differential equations in many variables. The integrability conditions…

General Physics · Physics 2023-08-30 Walaa I. Eshraim

We propose an efficient dual boson scheme, which extends the DMFT paradigm to collective excitations in correlated systems. The theory is fully self-consistent both on the one- and on the two-particle level, thus describing the formation of…

Strongly Correlated Electrons · Physics 2016-01-12 E. A. Stepanov , E. G. C. P. van Loon , A. A. Katanin , A. I. Lichtenstein , M. I. Katsnelson , A. N. Rubtsov

The theory of Self-Consistent Green's Function (SCGF) is reformulated in an explicit Nambu-covariant fashion for applications to many-body systems at non-zero temperature in symmetry-broken phases. This is achieved by extending the…

Nuclear Theory · Physics 2025-07-09 M. Drissi , A. Rios , C. Barbieri

Non equilibrium effective field theory is presented as an inhomogeneous field theory, using a formulation which is analogous to that of a gauge theory. This formulation underlines the importance of structural aspects of non-equilibrium,…

High Energy Physics - Theory · Physics 2007-05-23 Mark Burgess

We develop the continuum mechanics of quantum many-body systems in the linear response regime. The basic variable of the theory is the displacement field, for which we derive a closed equation of motion under the assumption that the…

Strongly Correlated Electrons · Physics 2015-05-13 Jianmin Tao , Xianlong Gao , G. Vignale , I. V. Tokatly

Recently Mazenko and Das and Mazenko introduced a non-equilibrium field theoretical approach to describe the statistical properties of a classical particle ensemble starting from the microscopic equations of motion of each individual…

Statistical Mechanics · Physics 2015-06-23 Celia Viermann , Felix Fabis , Elena Kozlikin , Robert Lilow , Matthias Bartelmann

We develop a Green's function method to evaluate the exact equilibrium particle-density profiles of noninteracting Fermi gases in external harmonic confinement in any spatial dimension and for arbitrary trap anisotropy. While in a…

Statistical Mechanics · Physics 2009-11-07 Patrizia Vignolo , Anna Minguzzi

In this article we review a less known unperturbative and powerful many-body method in the framework of classical statistical mechanics and then we show how it works by means of explicit calculations for a nontrivial classical model. The…

Statistical Mechanics · Physics 2007-05-23 A. Cavallo , F. Cosenza , L. De Cesare

We present a constructive derivation of a time-dependent deformation functional theory -- a collective variable approach to the nonequalibrium quantum many-body problem. It is shown that the motion of infinitesimal fluid elements (i.e. a…

Strongly Correlated Electrons · Physics 2011-09-19 I. V. Tokatly