scholarly journals Hamiltonian theory of classical and quantum gauge invariant perturbations in Bianchi I spacetimes

2020 ◽  
Vol 101 (12) ◽  
Author(s):  
Ivan Agullo ◽  
Javier Olmedo ◽  
V. Sreenath
Keyword(s):  
Gauge Invariant ◽  
Bianchi I ◽  
Hamiltonian Theory

scholarly journals xAct Implementation of the Theory of Cosmological Perturbation in Bianchi I Spacetimes

Mathematics ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 290 ◽  
Author(s):  
Ivan Agullo ◽  
Javier Olmedo ◽  
Vijayakumar Sreenath
Keyword(s):  
Phase Space ◽  
Degrees Of Freedom ◽  
Computational Algorithm ◽  
Tensor Algebra ◽  
Cosmological Perturbation ◽  
Gauge Invariant ◽  
Bianchi I ◽  
Space Formulation

This paper presents a computational algorithm to derive the theory of linear gauge invariant perturbations on anisotropic cosmological spacetimes of the Bianchi I type. Our code is based on the tensor algebra packages xTensor and xPert, within the computational infrastructure of xAct written in Mathematica. The algorithm is based on a Hamiltonian, or phase space formulation, and it provides an efficient and transparent way of isolating the gauge invariant degrees of freedom in the perturbation fields and to obtain the Hamiltonian generating their dynamics. The restriction to Friedmann–Lemaître–Robertson–Walker spacetimes is straightforward.

A note on the Hamiltonian theory of quantization. II

1947 ◽  
Vol 43 (2) ◽  
pp. 196-204 ◽  
Author(s):  
T. S. Chang
Keyword(s):  
Variational Principles ◽  
Initial Conditions ◽  
Equations Of Motion ◽  
Field Equations ◽  
Gauge Invariant ◽  
Commutation Relations ◽  
Hamiltonian Theory ◽  
Higher Derivatives ◽  
Missing Momenta ◽  
Derivatives Of

It is pointed out that the equations of motion for any field obtained by varying a Lagrangian subject to auxiliary conditions are exactly equivalent to a certain set of canonical equations and that the commutation relations between the dynamical variables for the latter equations are Lorentz-invariant. By extending the theory to Lagrangians containing higher derivatives of the field quantities, it is shown that any given set of field equations can be put into the canonical form, though it is not derived from variational principles. The question of Lagrangians with missing momenta is also considered. It is shown that if the Lagrangian is ‘gauge-invariant’, some of the p's must be missing and the corresponding Eulerian equations can be replaced by equations containing no q and then can be replaced by initial conditions. The commutation relations between gauge-invariant quantities are Lorentz-invariant. For Lagrangians which are not gauge-invariant but are such as to have missing momenta, the passage to quantum theory will in general give rise to non-Lorentz-invariant commutation relations. In both cases, the equations of motion can be cast in canonical forms.

A manifestly gauge-invariant Hamiltonian theory of the oscillation-centre dynamics

1987 ◽  
Vol 37 (3) ◽  
pp. 467-486 ◽  
Author(s):  
B. Weyssow ◽  
R. Balescu
Keyword(s):  
High Frequency ◽  
Ponderomotive Force ◽  
Hamiltonian Formalism ◽  
Gauge Invariant ◽  
Canonical Variables ◽  
Hamiltonian Theory ◽  
Special Cases ◽  
High Frequency Electromagnetic Field ◽  
Particle Velocities ◽  
Field Oscillation

The theory of the slow reaction of charged particles in the presence of a high-frequency electromagnetic field (oscillation-centre motion) is developed by using a Hamiltonian formalism with non-canonical variables and pseudo-canonical transformations. The flexibility introduced by the latter features allows us to construct a theory which is manifestly gauge-invariant and involves only physical concepts (electromagnetic fields and particle velocities instead of potentials and canonical momenta). A complete description of the oscillation-centre dynamics is derived. The known expressions of the ponderomotive force are derived as special cases of our theory.

Hamiltonian formulation of the Freedman–Townsend model of massive vector mesons

1991 ◽  
Vol 69 (5) ◽  
pp. 569-572 ◽  
Author(s):  
D. G. C. McKeon
Keyword(s):  
Effective Action ◽  
Invariant Theory ◽  
Hamiltonian Formulation ◽  
Power Counting ◽  
Constrained Systems ◽  
Vector Mesons ◽  
Gauge Invariant ◽  
Massive Vector ◽  
Hamiltonian Theory

A gauge invariant theory of massive vector mesons, formulated by Freedman and Townsend, is quantized using the Hamiltonian theory for reducible constrained systems of Batalin, Fradkin, and Vilkovisky. The effective action is Lorentz covariant in the gauge in which we work. All propagators have an ultraviolet behaviour that is consistent with power-counting renormalizability. We take this formulation of the Freedman–Townsend model to be consistent with unitarity.

scholarly journals EXTENDED OBSERVABLES IN HAMILTONIAN THEORIES WITH CONSTRAINTS

2001 ◽  
Vol 16 (26) ◽  
pp. 4271-4296 ◽  
Author(s):  
SIMON L. LYAKHOVICH ◽  
ROBERT MARNELIUS
Keyword(s):  
Phase Space ◽  
Differential Operators ◽  
Poisson Algebra ◽  
Dirac Bracket ◽  
Covariant Quantization ◽  
Mapping Procedure ◽  
Gauge Invariant ◽  
Hamiltonian Theory ◽  
Bracket Algebra ◽  
Constraint Surface

In a classical Hamiltonian theory with second-class constraints the phase space functions on the constraint surface are observables. We give general formulas for extended observables, which are expressions representing the observables in the enveloping unconstrained phase space. These expressions satisfy in the unconstrained phase space a Poisson algebra of the same form as the Dirac bracket algebra of the observables on the constraint surface. The general formulas involve new differential operators that differentiate the Dirac bracket. Similar extended observables are also constructed for theories with first-class constraints which, however, are gauge-dependent. For such theories one may also construct gauge-invariant extensions with similar properties. Whenever extended observables exist the theory is expected to allow for a covariant quantization. A mapping procedure is proposed for covariant quantization of theories with second-class constraints.

The Standard Theory

2017 ◽  
Author(s):  
John Iliopoulos
Keyword(s):  
Gauge Theory ◽  
Invariant Theory ◽  
Standard Theory ◽  
Strong Interactions ◽  
Gauge Invariant ◽  
Electromagnetic Interactions ◽  
Protons And Neutrons ◽  
Free Particles ◽  
Theoretical Predictions ◽  
Theory And Experiment

All ingredients of the previous chapters are combined in order to build a gauge invariant theory of the interactions among the elementary particles. We start with a unified model of the weak and the electromagnetic interactions. The gauge symmetry is spontaneously broken through the BEH mechanism and we identify the resulting BEH boson. Then we describe the theory known as quantum chromodynamics (QCD), a gauge theory of the strong interactions. We present the property of confinement which explains why the quarks and the gluons cannot be extracted out of the protons and neutrons to form free particles. The last section contains a comparison of the theoretical predictions based on this theory with the experimental results. The agreement between theory and experiment is spectacular.

scholarly journals Time Decay for Nonlinear Dissipative Schrödinger Equations in Optical Fields

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Nakao Hayashi ◽  
Chunhua Li ◽  
Pavel I. Naumkin
Keyword(s):  
Lower Bound ◽  
Positive Root ◽  
Schrodinger Equations ◽  
Schrödinger Equations ◽  
Time Decay ◽  
Large Initial Data ◽  
Initial Value ◽  
Optical Fields ◽  
Gauge Invariant ◽  
Dissipative Condition

We consider the initial value problem for the nonlinear dissipative Schrödinger equations with a gauge invariant nonlinearityλup-1uof orderpn<p≤1+2/nfor arbitrarily large initial data, where the lower boundpnis a positive root ofn+2p2-6p-n=0forn≥2andp1=1+2forn=1.Our purpose is to extend the previous results for higher space dimensions concerningL2-time decay and to improve the lower bound ofpunder the same dissipative condition onλ∈C:Im⁡ λ<0andIm⁡ λ>p-1/2pRe λas in the previous works.

scholarly journals Gauge invariance, polar coordinates and inflation

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Ali Akil ◽  
Xi Tong
Keyword(s):  
Coordinate System ◽  
Effective Potential ◽  
Gauge Invariance ◽  
Polar Coordinates ◽  
Quantum Corrections ◽  
Background Current ◽  
Gauge Invariant ◽  
Gauge Dependence ◽  
Current Term ◽  
Invariant Current

Abstract We point out the necessity of resolving the apparent gauge dependence in the quantum corrections of cosmological observables for Higgs-like inflation models. We highlight the fact that this gauge dependence is due to the use of an asymmetric background current which is specific to a choice of coordinate system in the scalar manifold. Favoring simplicity over complexity, we further propose a practical shortcut to gauge-independent inflationary observables by using effective potential obtained from a polar-like background current choice. We demonstrate this shortcut for several explicit examples and present a gauge-independent prediction of inflationary observables in the Abelian Higgs model. Furthermore, with Nielsen’s gauge dependence identities, we show that for any theory to all orders, a gauge-invariant current term gives a gauge-independent effective potential and thus gauge-invariant inflationary observables.

scholarly journals A master exceptional field theory

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Guillaume Bossard ◽  
Axel Kleinschmidt ◽  
Ergin Sezgin
Keyword(s):  
Field Theory ◽  
Gauge Invariance ◽  
Sigma Model ◽  
Linear Equations ◽  
Field Theories ◽  
Gauge Invariant ◽  
Non Linear ◽  
Non Linear Equations

Abstract We construct a pseudo-Lagrangian that is invariant under rigid E11 and transforms as a density under E11 generalised diffeomorphisms. The gauge-invariance requires the use of a section condition studied in previous work on E11 exceptional field theory and the inclusion of constrained fields that transform in an indecomposable E11-representation together with the E11 coset fields. We show that, in combination with gauge-invariant and E11-invariant duality equations, this pseudo-Lagrangian reduces to the bosonic sector of non-linear eleven-dimensional supergravity for one choice of solution to the section condi- tion. For another choice, we reobtain the E8 exceptional field theory and conjecture that our pseudo-Lagrangian and duality equations produce all exceptional field theories with maximal supersymmetry in any dimension. We also describe how the theory entails non-linear equations for higher dual fields, including the dual graviton in eleven dimensions. Furthermore, we speculate on the relation to the E10 sigma model.

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