The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Michael Dütsch - One of the best experts on this subject based on the ideXlab platform.
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Perturbative Gauge Invariance: electroweak theory II
Annalen der Physik, 1999Co-Authors: Andreas Aste, Günter Schaf, Michael DütschAbstract:A recent construction of the electroweak theory, based on perturbative quantum Gauge Invariance alone, is extended to the case of more generations of fermions with arbitrary mixing. The conditions implied by second order Gauge Invariance lead to an isolated solution for the ferm- ionic couplings in agreement with the standard model. Third order Gauge Invariance determines the Higgs potential. The resulting massive Gauge theory is manifestly Gauge invariant, after con- struction.
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Perturbative Gauge Invariance: the electroweak theory
Annalen der Physik, 1999Co-Authors: Michael Dütsch, Günter SchafAbstract:The concept of perturbative Gauge Invariance formulated exclusively by means of asymptotic fields is generalized to massive Gauge fields. Applying it to the electroweak theory leads to a complete fixing of couplings of scalar and ghost fields and of the coupling to leptons, in agreement with the standard theory. The W/Z mass ratio is also determined, as well as the chiral character of the fermions. We start directly with massive Gauge fields and leptons and, nevertheless, obtain a theory which satisfies perturbative Gauge Invariance.
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On Gauge Invariance and spontaneous symmetry breaking
Journal of Physics A, 1997Co-Authors: Andreas Aste, Günter Scharf, Michael DütschAbstract:We show how the widely used concept of spontaneous symmetry breaking can be explained in causal perturbation theory by introducing a perturbative version of quantum Gauge Invariance. Perturbative Gauge Invariance, formulated exclusively by means of asymptotic fields, is discussed for the simple example of Abelian U(1) Gauge theory (Abelian Higgs model). Our findings are relevant for the electroweak theory, as pointed out elsewhere.
Günter Scharf - One of the best experts on this subject based on the ideXlab platform.
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Violation of Quantum Gauge Invariance in Georgi-Glashow SU(5)
arXiv: High Energy Physics - Theory, 2004Co-Authors: Martin Ambauen, Günter ScharfAbstract:We check whether the SU(5) model, originally suggested by Georgi and Glashow, is compatible with perturbative quantum Gauge Invariance in first and second order for massive asymptotic Gauge fields. We see that this is not the case: the SU(5) grand unified model does not meet with our restrictions from second order Gauge Invariance.
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On Gauge Invariance and spontaneous symmetry breaking
Journal of Physics A, 1997Co-Authors: Andreas Aste, Günter Scharf, Michael DütschAbstract:We show how the widely used concept of spontaneous symmetry breaking can be explained in causal perturbation theory by introducing a perturbative version of quantum Gauge Invariance. Perturbative Gauge Invariance, formulated exclusively by means of asymptotic fields, is discussed for the simple example of Abelian U(1) Gauge theory (Abelian Higgs model). Our findings are relevant for the electroweak theory, as pointed out elsewhere.
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Gauge Invariance of massless QED
Physics Letters B, 1994Co-Authors: M. Dütsch, Tobias Hurth, Günter ScharfAbstract:Abstract A simple general proof of Gauge Invariance in QED is given in the framework of causal perturbation theory. It illustrates a method which can also be used in non-abelian Gauge theories.
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Gauge Invariance in finite QED
Nuovo Cimento Della Societa Italiana Di Fisica A-nuclei Particles and Fields, 1990Co-Authors: M. Dütsch, F. Krahe, Günter ScharfAbstract:Gauge Invariance is discussed in the causal approach to QED. It is proven that the iterative construction of theS-matrix by the method of Epstein and Glaser can be carried out in such a way that perturbative Gauge Invariance holds true. The proof rests on a careful analysis of the process of distribution splitting. In case of nontrivial distribution splitting Gauge Invariance implies the Ward-Takahashi identities.
Andreas Aste - One of the best experts on this subject based on the ideXlab platform.
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Perturbative Gauge Invariance: electroweak theory II
Annalen der Physik, 1999Co-Authors: Andreas Aste, Günter Schaf, Michael DütschAbstract:A recent construction of the electroweak theory, based on perturbative quantum Gauge Invariance alone, is extended to the case of more generations of fermions with arbitrary mixing. The conditions implied by second order Gauge Invariance lead to an isolated solution for the ferm- ionic couplings in agreement with the standard model. Third order Gauge Invariance determines the Higgs potential. The resulting massive Gauge theory is manifestly Gauge invariant, after con- struction.
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On Gauge Invariance and spontaneous symmetry breaking
Journal of Physics A, 1997Co-Authors: Andreas Aste, Günter Scharf, Michael DütschAbstract:We show how the widely used concept of spontaneous symmetry breaking can be explained in causal perturbation theory by introducing a perturbative version of quantum Gauge Invariance. Perturbative Gauge Invariance, formulated exclusively by means of asymptotic fields, is discussed for the simple example of Abelian U(1) Gauge theory (Abelian Higgs model). Our findings are relevant for the electroweak theory, as pointed out elsewhere.
C. Schwinn - One of the best experts on this subject based on the ideXlab platform.
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Gauge Invariance classes in spontaneously broken Gauge theories
2020Co-Authors: C. SchwinnAbstract:We determine the Gauge Invariance classes of tree level Feynman diagrams in spontaneously broken Gauge theories, providing a proof for the formalism of Gauge and flavor flips. We find new Gauge Invariance classes in theories with a nonlinearly realized scalar sector. In unitarity Gauge, the same Gauge Invariance classes correspond to a decomposition of the scattering amplitude into pieces that satisfy the relevant Ward identities individually. In theories with a linearly realized scalar sector in Rξ Gauge, no additional non-trivial Gauge Invariance classes exist compared to the unbroken case.
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Forests, Groves and Higgs Bosons: Gauge Invariance Classes in Spontaneously Broken Gauge Theories
arXiv: High Energy Physics - Phenomenology, 2003Co-Authors: C. SchwinnAbstract:We determine the Gauge Invariance classes of tree level Feynman diagrams in spontaneously broken Gauge theories, providing a proof for the formalism of Gauge and flavor flips. We find new Gauge Invariance classes in theories with a nonlinearly realized scalar sector. In unitarity Gauge, the same Gauge Invariance classes correspond to a decomposition of the scattering amplitude into pieces that satisfy the relevant Ward Identities individually. In theories with a linear realized scalar sector in R_\xi Gauge, no additional nontrivial Gauge Invariance classes exist compared to the unbroken case.
Priya Sharma - One of the best experts on this subject based on the ideXlab platform.
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Approach to Solving Quasiclassical Equations with Gauge Invariance
Journal of Low Temperature Physics, 2020Co-Authors: Priya SharmaAbstract:Quasiclassical equations with manifest Gauge Invariance are discussed in the context of unconventional singlet superconducting states in the static limit. Deviations of the quasiclassical propagator from its equilibrium solutions in the presence of magnetic fields and Hall terms are analysed in terms of a “ small ” parameter and a formulation developed to first order in “ small ”. A modified quasiclassical propagator is defined to this order that is a solution of a new Gauge-invariant Eilenberger-like equation with a normalization condition. A Riccati parametrization with manifest Gauge Invariance is proposed. Riccati equations are derived to leading order in “ small ” that are directly applicable to superconducting systems in the presence of magnetic fields.
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Approach to Solving Quasiclassical Equations with Gauge Invariance
arXiv: Superconductivity, 2019Co-Authors: Priya SharmaAbstract:Quasiclassical equations with manifest Gauge Invariance are discussed in the context of unconventional singlet superconducting states in the static limit. Deviations of the quasiclassical propagator from its equilibrium solutions in the presence of magnetic fields and Hall terms are analysed in terms of a *small* parameter and a formulation developed to first order in *small*. A modified quasiclassical propagator is defined to this order that is a solution of a new Gauge-invariant Eilenberger-like equation with a normalisation condition. A Ricatti parametrisation with manifest Gauge Invariance is proposed. This theory is directly applicable to homogenous d-wave order parameters in the presence of magnetic fields, such as in high-temperature superconductors.