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This PhD thesis presents a study of the effect and generation of non-adiabatic perturbations in Cosmology. We study adiabatic (curvature) and entropy (isocurvature) perturbations produced during a period of cosmological inflation that is…

Astrophysics · Physics 2007-05-23 Christopher Gordon

We apply the dynamical systems tools to study the asymptotic properties of a cosmological model based on a non-linear modification of General Relativity in which the standard Einstein-Hilbert action is replaced by one of Dirac-Born-Infeld…

General Relativity and Quantum Cosmology · Physics 2010-05-12 Ricardo García-Salcedo , Tame Gonzalez , Claudia Moreno , Yunelsy Napoles , Yoelsy Leyva , Israel Quiros

The results of a recent paper [0808.2909] are generalized. A more detailed proof is presented that under essentially all conditions, the non-linear classical equations governing matter and gravitation in cosmology have ``adiabatic''…

High Energy Physics - Phenomenology · Physics 2010-04-21 Steven Weinberg

The spectrum of adiabatic density perturbation generated during inflation is studied in the case the time derivative of an inflation-driving scalar field (inflaton) vanishes at some time during inflation. It is shown that the nondecaying…

Astrophysics · Physics 2009-10-31 Osamu Seto , Jun'ichi Yokoyama , Hideo Kodama

This paper studies the oscillatory behavior of solutions to linear nonautonomous impulsive differential equations with piecewise constant arguments, including both advanced and delayed cases \[ x'(t) = a(t)x(t) + b(t)x([t-k]), \quad k \in…

Dynamical Systems · Mathematics 2026-03-31 Ricardo Torres Naranjo , Eugenio Trucco Vera , Özkan Öcal

We show that the field equations for cosmological perturbations in Newtonian gauge always have an adiabatic solution, for which a quantity ${\cal R}$ is non-zero and constant in all eras in the limit of large wavelength, so that it can be…

Astrophysics · Physics 2009-11-07 Steven Weinberg

The current understanding of mechanical feedback is reviewed by evaluating the standard, adiabatic model for shell formation and evolution. This model is relevant to phenomena ranging from individual stellar-wind bubbles to galactic…

Astrophysics · Physics 2007-05-23 M. S. Oey , C. J. Clarke , P. Massey

We show that recent results on adiabatic theory for interacting gapped many-body systems on finite lattices remain valid in the thermodynamic limit. More precisely, we prove a generalised super-adiabatic theorem for the automorphism group…

Mathematical Physics · Physics 2024-06-19 Joscha Henheik , Stefan Teufel

An analytical method for investigation of the evolution of dynamical systems {\it with independent on time accuracy} is developed for perturbed Hamiltonian systems. The error-free estimation using of computer algebra enables the application…

Instrumentation and Methods for Astrophysics · Physics 2016-12-13 A. V. Gurzadyan , A. A. Kocharyan

We study the out of equilibrium dynamics of inflationary phase transitions and compute the resulting spectrum of metric perturbations relevant to observation. We show that simple single field models of inflation may produce an adiabatic…

Astrophysics · Physics 2016-11-03 D. Cormier , R. Holman

We simulate the dynamics of paramagnetic colloidal particles that are placed above a magnetic hexagonal pattern and exposed to an external field periodically changing its direction along a control loop. The conformation of three colloidal…

Soft Condensed Matter · Physics 2022-10-12 Adrian Ernst , Anna M. E. B. Rossi , Thomas M. Fischer

Adiabatic quantum computation employs a slow change of a time-dependent control function (or functions) to interpolate between an initial and final Hamiltonian, which helps to keep the system in the instantaneous ground state. When the…

Quantum Physics · Physics 2014-06-26 Constantin Brif , Matthew D. Grace , Mohan Sarovar , Kevin C. Young

For most stochastic dynamical systems, variables which are tightly regulated tend to respond slowly to external changes. This idea is often discussed for applicable systems, within a linear response regime, through the Fluctuation…

General Physics · Physics 2017-11-15 Nash Rochman , Sean X. Sun

Adiabatic invariants are introduced and shown to provide an approximate second integral of motion for the non-integrable Dicke model, in the energy region where the system exhibits a regular dynamics. This low-energy region is always…

Both orbital and rotational dynamics employ the method of variation of parameters. We express, in a non-perturbed setting, the coordinates (Cartesian, in the orbital case, or Eulerian in the rotation case) via the time and six adjustable…

Astrophysics · Physics 2007-05-23 Michael Efroimsky

We consider instabilities of a single mode with finite wavenumber in inversion symmetric spatially one dimensional systems, where the character of the bifurcation changes from sub- to supercritical behaviour. Starting from a general…

patt-sol · Physics 2009-10-31 Wolfram Just , Frank Matthäus , Herwig Sauermann

The behaviour of a space-modulated, so-called "argumental" oscillator is studied, which is represented by a model having an even-parity space-modulating function. Analytic expressions of a stability criterion and of discrete energy levels…

Chaotic Dynamics · Physics 2016-06-30 Daniel Cintra , Pierre Argoul

This paper explores a mathematical technique for deriving dynamical invariants (i.e. constants of motion) in time-dependent gravitational potentials. The method relies on the construction of a canonical transformation that removes the…

Astrophysics of Galaxies · Physics 2015-06-16 Jorge Peñarrubia

This study details the conditions under which strong-coupling perturbation theory can be applied to the molecular crystal model, a fundamental theoretical tool for analysis of the polaron properties. I show that lattice dimensionality and…

Superconductivity · Physics 2009-10-31 marco zoli

Perturbation theory with respect to the kinetic energy of the heavy component of a two-component quantum system is introduced. An effective Hamiltonian that is accurate to second order in the inverse heavy mass is derived. It contains a new…

Quantum Physics · Physics 2024-06-21 Ryan Requist
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