Covariant generation of vector gauge bosons in non-Abelian gauge theories

1981 ◽  
Vol 30 (17) ◽  
pp. 523-529 ◽  
Author(s):  
J. Julve ◽  
J. Leon ◽  
A. Tiemblo ◽  
M. Ramon-Medrano
Keyword(s):  
Gauge Theories ◽  
Gauge Bosons ◽  
Abelian Gauge ◽  
Vector Gauge

scholarly journals Axions are blind to anomalies

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Jérémie Quevillon ◽  
Christopher Smith
Keyword(s):  
Ward Identity ◽  
Gauge Theories ◽  
Feynman Diagrams ◽  
Explicit Calculation ◽  
Gauge Bosons ◽  
Vector Gauge

Abstract The axion couplings to SM gauge bosons are derived in various models, and shown to always arise entirely from non-anomalous fermion loops. They are thus independent of the anomaly structure of the model. This fact is without consequence for vector gauge interactions like QCD and QED, but has a major impact for chiral gauge theories. For example, in the DFSZ axion model, the couplings of axions to electroweak gauge bosons do not follow the pattern expected from chiral anomalies, as we prove by an explicit calculation. The reason for this mismatch is traced back to triangle Feynman diagrams sensitive to the anomalous breaking of the vector Ward identity, and is ultimately related to the conservation of baryon and lepton numbers. Though our analyses are entirely done for true axion models, this observation could have important consequences for axion-like particle searches.

scholarly journals Using Covariant Polarisation Sums in QCD

2022 ◽  
Vol 137 (1) ◽  
Author(s):  
M. Kachelrieß ◽  
M. N. Malmquist
Keyword(s):  
Gauge Boson ◽  
Ward Identity ◽  
Gauge Theories ◽  
Feynman Rule ◽  
Optical Theorem ◽  
Gauge Bosons ◽  
Abelian Gauge ◽  
Feynman Gauge ◽  
Cross Terms ◽  
External Gauge

AbstractCovariant gauges lead to spurious, non-physical polarisation states of gauge bosons. In QED, the use of the Feynman gauge, $$\sum _{\lambda } \varepsilon _\mu ^{(\lambda )}\varepsilon _\nu ^{(\lambda )*} = -\eta _{\mu \nu }$$ ∑ λ ε μ ( λ ) ε ν ( λ ) ∗ = - η μ ν , is justified by the Ward identity which ensures that the contributions of non-physical polarisation states cancel in physical observables. In contrast, the same replacement can be applied only to a single external gauge boson in squared amplitudes of non-abelian gauge theories like QCD. In general, the use of this replacement requires to include external Faddeev–Popov ghosts. We present a pedagogical derivation of these ghost contributions applying the optical theorem and the Cutkosky cutting rules. We find that the resulting cross terms $$\mathcal {A}(c_1,\bar{c}_1;\ldots )\mathcal {A}(\bar{c}_1,c_1;\ldots )^*$$ A ( c 1 , c ¯ 1 ; … ) A ( c ¯ 1 , c 1 ; … ) ∗ between ghost amplitudes cannot be transformed into $$(-1)^{n/2}|\mathcal {A}(c_1,\bar{c}_1;\ldots )|^2$$ ( - 1 ) n / 2 | A ( c 1 , c ¯ 1 ; … ) | 2 in the case of more than two ghosts. Thus the Feynman rule stated in the literature holds only for two external ghosts, while it is in general incorrect.

scholarly journals HIGGS MECHANISM FOR GRAVITONS

2010 ◽  
Vol 25 (28) ◽  
pp. 2411-2421 ◽  
Author(s):  
ICHIRO ODA
Keyword(s):  
Cosmological Constant ◽  
Gauge Theories ◽  
Minkowski Spacetime ◽  
Scalar Fields ◽  
Higgs Mechanism ◽  
Spacetime Dimension ◽  
Gauge Bosons ◽  
Higher Derivative ◽  
Vector Gauge ◽  
Arbitrary Potential

Just like the vector gauge bosons in the gauge theories, it is now known that gravitons acquire mass in the process of spontaneous symmetry breaking of diffeomorphisms through the condensation of scalar fields. The point is that we should find the gravitational Higgs mechanism such that it results in massive gravity in a flat Minkowski spacetime without non-unitary propagating modes. This is usually achieved by including higher-derivative terms in scalars and tuning the cosmological constant to be a negative value in a proper way. Recently, a similar but different gravitational Higgs mechanism has been advocated by Chamseddine and Mukhanov where one can relax the negative cosmological constant to zero or positive one. In this work, we investigate why the non-unitary ghost mode decouples from physical Hilbert space in a general spacetime dimension. Moreover, we generalize the model to possess an arbitrary potential and clarify under what conditions the general model exhibits the gravitational Higgs mechanism. By searching for solutions to the conditions, we arrive at two classes of potentials exhibiting gravitational Higgs mechanism. One class includes the model by Chamseddine and Mukhanov in a specific case while the other is a completely new model.

DECONFINEMENT IN (2 + 1)-DIMENSIONAL NON-ABELIAN GAUGE THEORIES WITH FUNDAMENTAL FERMIONS

1992 ◽  
Vol 07 (25) ◽  
pp. 2287-2297
Author(s):  
A. KOVNER ◽  
B. ROSENSTEIN
Keyword(s):  
Perturbation Theory ◽  
Gauge Theories ◽  
Goldstone Boson ◽  
Charged Particles ◽  
Baryon Number ◽  
Lagrangian Approach ◽  
The Other ◽  
Gauge Bosons ◽  
Abelian Gauge

Non-Abelian gauge theories with fundamental fermions are analyzed using dual Lagrangian approach. It is found that in certain range of parameters the baryon number symmetry is spontaneously broken and one of the gauge bosons is identified as the corresponding Goldstone boson. It therefore remains massless beyond perturbation theory. All the other gauge bosons acquire a mass due to one-loop and monopole effects. Correspondingly, unlike in theories with bosonic matter only, one type of charged particles is not linearly confined.

Geometry and Quantum Dynamics

2017 ◽  
Author(s):  
Laurent Baulieu ◽  
John Iliopoulos ◽  
Roland Sénéor
Keyword(s):  
General Relativity ◽  
Quantum Dynamics ◽  
Gauge Theories ◽  
Brst Symmetry ◽  
Abelian Gauge ◽  
Yang Mills ◽  
History Of ◽  
Brst Invariance

A geometrical derivation of Abelian and non- Abelian gauge theories. The Faddeev–Popov quantisation. BRST invariance and ghost fields. General discussion of BRST symmetry. Application to Yang–Mills theories and general relativity. A brief history of gauge theories.

scholarly journals Cwebs beyond three loops in multiparton amplitudes

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Neelima Agarwal ◽  
Lorenzo Magnea ◽  
Sourav Pal ◽  
Anurag Tripathi
Keyword(s):  
Gauge Theories ◽  
Anomalous Dimension ◽  
Wilson Line ◽  
Building Blocks ◽  
Feynman Diagrams ◽  
Loop Order ◽  
Abelian Gauge ◽  
Sum Rule ◽  
Combinatorial Properties ◽  
Low Dimensional

Abstract Correlators of Wilson-line operators in non-abelian gauge theories are known to exponentiate, and their logarithms can be organised in terms of collections of Feynman diagrams called webs. In [1] we introduced the concept of Cweb, or correlator web, which is a set of skeleton diagrams built with connected gluon correlators, and we computed the mixing matrices for all Cwebs connecting four or five Wilson lines at four loops. Here we complete the evaluation of four-loop mixing matrices, presenting the results for all Cwebs connecting two and three Wilson lines. We observe that the conjuctured column sum rule is obeyed by all the mixing matrices that appear at four-loops. We also show how low-dimensional mixing matrices can be uniquely determined from their known combinatorial properties, and provide some all-order results for selected classes of mixing matrices. Our results complete the required colour building blocks for the calculation of the soft anomalous dimension matrix at four-loop order.

scholarly journals Covariant phase space and soft factorization in non-Abelian gauge theories

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Temple He ◽  
Prahar Mitra
Keyword(s):  
Phase Space ◽  
Ward Identity ◽  
Gauge Theories ◽  
Minkowski Spacetime ◽  
Soft Gluon ◽  
Careful Study ◽  
Abelian Gauge ◽  
Gauge Sector ◽  
Vacuum States ◽  
The One

Abstract We perform a careful study of the infrared sector of massless non-abelian gauge theories in four-dimensional Minkowski spacetime using the covariant phase space formalism, taking into account the boundary contributions arising from the gauge sector of the theory. Upon quantization, we show that the boundary contributions lead to an infinite degeneracy of the vacua. The Hilbert space of the vacuum sector is not only shown to be remarkably simple, but also universal. We derive a Ward identity that relates the n-point amplitude between two generic in- and out-vacuum states to the one computed in standard QFT. In addition, we demonstrate that the familiar single soft gluon theorem and multiple consecutive soft gluon theorem are consequences of the Ward identity.

Fixed point structure of 3D abelian gauge theories

1999 ◽  
Author(s):  
Taichi Itoh ◽  
Yoonbai Kim
Keyword(s):  
Fixed Point ◽  
Gauge Theories ◽  
Abelian Gauge

scholarly journals Gauge Boson Condensation and Symmetry Breaking Patterns in Non-Abelian Gauge Theories

1982 ◽  
Vol 67 (1) ◽  
pp. 297-308 ◽  
Author(s):  
T. Inami ◽  
S. Watamura
Keyword(s):  
Symmetry Breaking ◽  
Gauge Boson ◽  
Gauge Theories ◽  
Abelian Gauge

Noncompact formulation of Abelian gauge theories on the lattice and charge quantization

1989 ◽  
Vol 233 (1-2) ◽  
pp. 187-191 ◽  
Author(s):  
G. de Franceschi ◽  
F. Palumbo
Keyword(s):  
Gauge Theories ◽  
Abelian Gauge ◽  
Charge Quantization
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