Gauge-fixing dependence of gluon and quark-damping rates in hot quantum chromodynamics

1993 ◽  
Vol 71 (5-6) ◽  
pp. 208-214 ◽  
Author(s):  
R. Baier ◽  
G. Kunstatter ◽  
D. Schiff
Keyword(s):  
Quantum Chromodynamics ◽  
High Temperatures ◽  
Ward Identities ◽  
Gauge Fixing ◽  
Hard Thermal Loops

The recently observed gauge-fixing dependence in covariant gauges of the damping rates of the quantum chromodynamics (QCD) gluonic and fermionic excitations at high temperatures and long wavelengths is reviewed. The analysis is based on the method by Braaten and Pisarski for resumming hard thermal loops using the Ward identities satisfied by the effective propagators and vertex functions. A proposed resolution of the gauge problem by regularizing the mass singularities is also discussed.

Transversality of the resummed thermal gluon self-energy

1993 ◽  
Vol 71 (5-6) ◽  
pp. 256-261 ◽  
Author(s):  
G. Kunstatter
Keyword(s):  
Quantum Chromodynamics ◽  
Imaginary Part ◽  
The Self ◽  
Ward Identities ◽  
Generating Functional ◽  
The Real ◽  
Self Energy ◽  
Gauge Fixing

The perturbative Ward identities obeyed by the effective vertices and propagators for thermal quantum chromodynamics (QCD) have recently been used to prove to order g2T the on-shell transversality of the imaginary part of the (resummed) gluon self-energy in all linear gauges. Here the same result is derived for both the real and imaginary parts of the self-energy using the nonperturbative gauge-fixing identities obeyed by the generating functional for QCD.

scholarly journals ON THE QUANTUM CHROMODYNAMICS OF A MASSIVE VECTOR FIELD IN THE ADJOINT REPRESENTATION

2013 ◽  
Vol 28 (14) ◽  
pp. 1350054 ◽  
Author(s):  
ALFONSO R. ZERWEKH
Keyword(s):  
Vector Field ◽  
Quantum Chromodynamics ◽  
Extra Dimensions ◽  
Scalar Fields ◽  
Discrete Symmetry ◽  
Adjoint Representation ◽  
Coupling Constants ◽  
Gauge Symmetries ◽  
Gauge Fixing ◽  
Definition Of

In this paper, we explore the possibility of constructing the quantum chromodynamics of a massive color-octet vector field without introducing higher structures like extended gauge symmetries, extra dimensions or scalar fields. We show that gauge invariance is not enough to constraint the couplings. Nevertheless, the requirement of unitarity fixes the values of the coupling constants, which otherwise would be arbitrary. Additionally, it opens a new discrete symmetry which makes the coloron stable and avoid its resonant production at a collider. On the other hand, a judicious definition of the gauge fixing terms modifies the propagator of the massive field making it well-behaved in the ultraviolet limit. The relation between our model and the more general approach based on extended gauge symmetries is also discussed.

Deducing hard thermal loops from Ward identities

1990 ◽  
Vol 339 (2) ◽  
pp. 310-324 ◽  
Author(s):  
Eric Braaten ◽  
Robert D. Pisarski
Keyword(s):  
Ward Identities ◽  
Hard Thermal Loops

scholarly journals Aspects on Effective Theories and the QCD Transition

Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 945
Author(s):  
Angel Gómez Nicola
Keyword(s):  
Phase Diagram ◽  
Perturbation Theory ◽  
Quantum Chromodynamics ◽  
Chiral Symmetry ◽  
Current Knowledge ◽  
Chiral Symmetry Restoration ◽  
Chiral Perturbation ◽  
Ward Identities ◽  
Hadron Gas ◽  
Effective Theories

We review recent advances in the understanding of the Quantum Chromodynamics (QCD) transition and its nature, paying special attention to the analysis of chiral symmetry restoration within different approaches based on effective theories. After presenting some of the main aspects of the current knowledge of the phase diagram from the theoretical, experimental and lattice sides, we discuss some recent problems where approaches relying on effective theories have been particularly useful. In particular, the combination of ideas such as Chiral Perturbation Theory, unitarity and Ward Identities allows us to describe successfully several observables of interest. This is particularly relevant for quantities expected to be dominated by the light meson components of the hadron gas such as the scalar and topological susceptibilities. In addition, ward identities and effective Lagrangians provide systematic results regarding chiral and U ( 1 ) A partner degeneration properties which are of great importance for the interplay between those two transitions and the nature of chiral symmetry restoration. Special attention is paid to the connection of this theoretical framework with lattice simulations.

scholarly journals TWO-DIMENSIONAL QUANTUM CHROMODYNAMICS ON A CYLINDER

1992 ◽  
Vol 07 (40) ◽  
pp. 3783-3788 ◽  
Author(s):  
S. GURUSWAMY ◽  
S.G. RAJEEV
Keyword(s):  
Quantum Chromodynamics ◽  
Gauge Field ◽  
Light Cone ◽  
Wilson Loop ◽  
Degrees Of Freedom ◽  
Fock Space ◽  
Two Dimensional ◽  
Gauge Fixing ◽  
Dynamical Degrees

We study two-dimensional quantum chromodynamics with massive quarks on a cylinder in a light-cone formalism. We eliminate the non-dynamical degrees of freedom and express the theory in terms of the quark and Wilson loop variables. It is possible to perform this reduction without gauge fixing. The fermionic Fock space can be defined independent of the gauge field in this light-cone formalism.

scholarly journals $$ \mathcal{N} $$ = 2 AdS4 supergravity, holography and Ward identities

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
L. Andrianopoli ◽  
B. L. Cerchiai ◽  
R. Matrecano ◽  
O. Miskovic ◽  
R. Noris ◽  
...  
Keyword(s):  
Equations Of Motion ◽  
Three Dimensional ◽  
Antisymmetric Part ◽  
Ward Identities ◽  
Four Dimensions ◽  
Conformal Field ◽  
Schouten Tensor ◽  
Gauge Fixing ◽  
Dimensional Boundary ◽  
Fermionic Fields

Abstract We develop in detail the holographic framework for an $$ \mathcal{N} $$ N = 2 pure AdS supergravity model in four dimensions, including all the contributions from the fermionic fields and adopting the Fefferman-Graham parametrization. We work in the first order formalism, where the full superconformal structure can be kept manifest in principle, even if only a part of it is realized as a symmetry on the boundary, while the remainder has a non-linear realization. Our study generalizes the results presented in antecedent literature and includes a general discussion of the gauge-fixing conditions on the bulk fields which yield the asymptotic symmetries at the boundary. We construct the corresponding super- conformal currents and show that they satisfy the related Ward identities when the bulk equations of motion are imposed. Consistency of the holographic setup requires the super- AdS curvatures to vanish at the boundary. This determines, in particular, the expression of the super-Schouten tensor of the boundary theory, which generalizes the purely bosonic Schouten tensor of standard gravity by including gravitini bilinears. The same applies to the superpartner of the super-Schouten tensor, the conformino. Furthermore, the vanishing of the supertorsion poses general constraints on the sources of the three-dimensional boundary conformal field theory and requires that the super-Schouten tensor is endowed with an antisymmetric part proportional to a gravitino-squared term.

scholarly journals The Feynman rules for the SMEFT in the background field gauge

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Tyler Corbett
Keyword(s):  
Background Field ◽  
Field Method ◽  
Effective Field ◽  
Ward Identities ◽  
The Standard Model ◽  
Gauge Fixing ◽  
Feynman Rules ◽  
Supplementary Material ◽  
Background Field Method ◽  
Mass Terms

Abstract We present a package for FeynRules which derives the Feynman rules for the Standard Model Effective Field Theory up to dimension-six using the background field method for gauge fixing. The package includes operators which shift the kinetic and mass terms of the Lagrangian up to dimension-eight and including dimension-six squared effects consistently. To the best of the author’s knowledge this is the first publicly available package to include dimension-six squared effects consistently. The package is validated in a partner publication by analyzing the Ward Identities at dimension-six and one-loop order. We also extend the partner work in this article by including the dimension-six squared effects further demonstrating the consistency of their implementation. In doing so we find that failure to consistently include field shifts to dimension-six squared causes a breakdown in the Ward identities implying concerns about many calculations in the literature which do not properly incorporate these effects.The FeynRules files, as well as Mathematica notebooks performing the relevant calculations, can be downloaded from the FeynRules website and are included as supplementary material to this publication.

scholarly journals Gauge fixing, BRS invariance and Ward identities for randomly stirred flows

2009 ◽  
Vol 814 (3) ◽  
pp. 522-548 ◽  
Author(s):  
Arjun Berera ◽  
David Hochberg
Keyword(s):  
Ward Identities ◽  
Gauge Fixing

Damping of fermions in hot gauge theories

1993 ◽  
Vol 71 (5-6) ◽  
pp. 252-255
Author(s):  
R. Kobes ◽  
G. Kunstatter ◽  
K. Mak
Keyword(s):  
Wide Class ◽  
Gauge Theories ◽  
Mass Shell ◽  
Ward Identities ◽  
Massless Fermion ◽  
Long Wavelength ◽  
Wavelength Limit ◽  
Cutoff Dependence ◽  
Damping Rate ◽  
Hard Thermal Loops

The calculation of the massless fermion damping rate to order g2T in the long-wavelength limit of hot gauge theories using the recently developed resummation methods in terms of hard thermal loops is reviewed. Ward identities between the effective propagators and vertices are used to formally prove the gauge independence of the damping rate to this order in a wide class of gauges. We also discuss some aspects of the cutoff dependence of the gauge-dependent terms proportional to the mass-shell condition.

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