scholarly journals Effective action for gauge bosons

2019 ◽  
Vol 99 (1) ◽  
Author(s):  
Jérémie Quevillon ◽  
Christopher Smith ◽  
Selim Touati
Keyword(s):  
Effective Action ◽  
Gauge Bosons

THE EFFECTIVE ACTION FOR COMPOSITE HIGGS PARTICLES

1992 ◽  
Vol 07 (30) ◽  
pp. 7561-7578
Author(s):  
STEPHAN SIEGEMUND-BROKA
Keyword(s):  
Effective Action ◽  
Dyson Equation ◽  
The Self ◽  
Composite Fermion ◽  
Gauge Bosons ◽  
Scalar Particles ◽  
Composite Higgs ◽  
Gauge Symmetries ◽  
Background Fields ◽  
Higgs Fields

There is reason to believe that massive composite (fermion-antifermion) scalar particles closely resembling the usual fundamental scalar Higgs fields exist in theories with dynamically broken gauge symmetries. This composite Higgs couples directly to the fermions in proportion to their symmetry-violating self-energies. Induced couplings to the gauge bosons and self-couplings are calculated as loop effects. This involves deriving the effective action in terms of the full propagators and background fields. The couplings between the composite Higgs and the gauge bosons are the same as those in models with fundamental scalars. The self-couplings are determined and fix all parameters associated with the composite scalars. Comments regarding extending this work to higher orders and concerning the symmetry-violating solutions to the fermion Schwinger-Dyson equation are given.

THE BACKGROUND FIELD METHOD AND THE ANOMALIES OF THE HETEROTIC σ-MODEL IN A CURVED (1, 0) SUPERSPACE

1991 ◽  
Vol 06 (17) ◽  
pp. 2971-2998 ◽  
Author(s):  
S.V. KETOV ◽  
O.A. SOLOVIEV
Keyword(s):  
Effective Action ◽  
Background Field ◽  
Field Method ◽  
Low Energy ◽  
Heterotic String ◽  
Explicit Calculation ◽  
Two Dimensional ◽  
Gauge Bosons ◽  
Background Field Method ◽  
Background Fields

The covariant (in the σ-model sense) background field method for calculating the anomalies of the heterotic string propagating on the background of its massless modes is developed in a curved superspace of the two-dimensional (1, 0) supergravity. As the massless background fields, we use a metric, an antisymmetric tensor, a dilaton and gauge bosons. Explicit calculation of the anomalies up to five loops is performed and the results are found to be in agreement with the known facts about the heterotic string low-energy effective action. The dilaton-dependent corrections to the anomalies at the two- and three-loop levels are shown to be absent.

Effective action on global warming?

1990 ◽  
Vol 4 (6) ◽  
pp. 262
Author(s):  
P.R. Wyman
Keyword(s):  
Global Warming ◽  
Effective Action

scholarly journals More on complex Sachdev-Ye-Kitaev eternal wormholes

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Pengfei Zhang
Keyword(s):  
Black Hole ◽  
Ground State ◽  
Effective Action ◽  
Chemical Potential ◽  
Specific Charge ◽  
Zero Temperature ◽  
Small Coupling ◽  
Chemical Potentials ◽  
Quench Dynamics ◽  
Two Sides

Abstract In this work, we study a generalization of the coupled Sachdev-Ye-Kitaev (SYK) model with U(1) charge conservations. The model contains two copies of the complex SYK model at different chemical potentials, coupled by a direct hopping term. In the zero-temperature and small coupling limit with small averaged chemical potential, the ground state is an eternal wormhole connecting two sides, with a specific charge Q = 0, which is equivalent to a thermofield double state. We derive the conformal Green’s functions and determine corresponding IR parameters. At higher chemical potential, the system transit into the black hole phase. We further derive the Schwarzian effective action and study its quench dynamics. Finally, we compare numerical results with the analytical predictions.

scholarly journals New bi-harmonic superspace formulation of 4D, $$ \mathcal{N} $$ = 4 SYM theory

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
I. L. Buchbinder ◽  
E. A. Ivanov ◽  
V. A. Ivanovskiy
Keyword(s):  
Effective Action ◽  
Harmonic Superspace ◽  
Four Dimensions ◽  
Yang Mills ◽  
Convenient Tool ◽  
Leading Term

Abstract We develop a novel bi-harmonic $$ \mathcal{N} $$ N = 4 superspace formulation of the $$ \mathcal{N} $$ N = 4 supersymmetric Yang-Mills theory (SYM) in four dimensions. In this approach, the $$ \mathcal{N} $$ N = 4 SYM superfield constraints are solved in terms of on-shell $$ \mathcal{N} $$ N = 2 harmonic superfields. Such an approach provides a convenient tool of constructing the manifestly $$ \mathcal{N} $$ N = 4 supersymmetric invariants and further rewriting them in $$ \mathcal{N} $$ N = 2 harmonic superspace. In particular, we present $$ \mathcal{N} $$ N = 4 superfield form of the leading term in the $$ \mathcal{N} $$ N = 4 SYM effective action which was known previously in $$ \mathcal{N} $$ N = 2 superspace formulation.

scholarly journals The fermionic universal one-loop effective action

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Sebastian A. R. Ellis ◽  
Jérémie Quevillon ◽  
Pham Ngoc Hoa Vuong ◽  
Tevong You ◽  
Zhengkang Zhang
Keyword(s):  
Path Integral ◽  
Effective Action ◽  
Covariant Derivative ◽  
Heavy Fermion ◽  
Axial Vector ◽  
Derivative Expansion ◽  
Universal Structure ◽  
Pseudo Scalar ◽  
Matching Techniques ◽  
Analytical Expressions

Abstract Recent development of path integral matching techniques based on the covariant derivative expansion has made manifest a universal structure of one-loop effective Lagrangians. The universal terms can be computed once and for all to serve as a reference for one-loop matching calculations and to ease their automation. Here we present the fermionic universal one-loop effective action (UOLEA), resulting from integrating out heavy fermions (Dirac or Majorana) with scalar, pseudo-scalar, vector and axial-vector couplings. We also clarify the relation of the new terms computed here to terms previously computed in the literature and those that remain to complete the UOLEA. Our results can be readily used to efficiently obtain analytical expressions for effective operators arising from heavy fermion loops [13].

scholarly journals Neutrino oscillation constraints on U(1)′ models: from non-standard interactions to long-range forces

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Pilar Coloma ◽  
M. C. Gonzalez-Garcia ◽  
Michele Maltoni
Keyword(s):  
Contact Interaction ◽  
Equivalence Principle ◽  
Laboratory Experiments ◽  
Global Analysis ◽  
Gauge Bosons ◽  
Lepton Flavor ◽  
Long Baseline ◽  
Oscillation Analysis ◽  
Weakly Coupled ◽  
Effective Contact

Abstract We quantify the effect of gauge bosons from a weakly coupled lepton flavor dependent U(1)′ interaction on the matter background in the evolution of solar, atmospheric, reactor and long-baseline accelerator neutrinos in the global analysis of oscillation data. The analysis is performed for interaction lengths ranging from the Sun-Earth distance to effective contact neutrino interactions. We survey ∼ 10000 set of models characterized by the six relevant fermion U(1)′ charges and find that in all cases, constraints on the coupling and mass of the Z′ can be derived. We also find that about 5% of the U(1)′ model charges lead to a viable LMA-D solution but this is only possible in the contact interaction limit. We explicitly quantify the constraints for a variety of models including $$ \mathrm{U}{(1)}_{B-3{L}_e} $$ U 1 B − 3 L e , $$ \mathrm{U}{(1)}_{B-3{L}_{\mu }} $$ U 1 B − 3 L μ , $$ \mathrm{U}{(1)}_{B-3{L}_{\tau }} $$ U 1 B − 3 L τ , $$ \mathrm{U}{(1)}_{B-\frac{3}{2}\left({L}_{\mu }+{L}_{\tau}\right)} $$ U 1 B − 3 2 L μ + L τ , $$ \mathrm{U}{(1)}_{L_e-{L}_{\mu }} $$ U 1 L e − L μ , $$ \mathrm{U}{(1)}_{L_e-{L}_{\tau }} $$ U 1 L e − L τ , $$ \mathrm{U}{(1)}_{L_e-\frac{1}{2}\left({L}_{\mu }+{L}_{\tau}\right)} $$ U 1 L e − 1 2 L μ + L τ . We compare the constraints imposed by our oscillation analysis with the strongest bounds from fifth force searches, violation of equivalence principle as well as bounds from scattering experiments and white dwarf cooling. Our results show that generically, the oscillation analysis improves over the existing bounds from gravity tests for Z′ lighter than ∼ 10−8→ 10−11 eV depending on the specific couplings. In the contact interaction limit, we find that for most models listed above there are values of g′ and MZ′ for which the oscillation analysis provides constraints beyond those imposed by laboratory experiments. Finally we illustrate the range of Z′ and couplings leading to a viable LMA-D solution for two sets of models.

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