Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 23 for “"Gauge Invariance"”.
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Non-local gauge field theory
This is a study of Non-Local Gauge Invariant Quantum Field Theory. NonLocal gauge invariance is an extension of the group of local gauge transformations that has been extensively used in construction of physical theories. We show how this larger group is rich enough to accommodate a new theory of …
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Towards Error-Resilience in Quantum Simulation of Lattice Gauge Theories
… rewarding target is given by lattice gauge theories. The fundamental principle of gauge-invariance imposes local gauge constraints upon their constituents, e.g. charged matter and the electric gauge field, which are highly challenging to engineer and which lead to intriguing yet not …
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Collinear divergences and factorization in perturbative QCD
… by gluon fusion. After this the issue of gauge invariance in this collinear scheme is addressed and it is realized that the collinear scheme fails to be gauge invariant. A more general analysis of collinear divergences and the phase space integrated over to calculate cross sections is …
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Numerical analysis for quantum electrodynamics in the ultrastrong coupling regime
… physical system. This thesis explores the gauge-invariance issues of various Hamiltonians that are utilized in quantum electrodynamics. With the validated Hamiltonians, numerical transformations aimed at producing Hamiltonians that are more amenable to tensor network algorithms are …
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Observations and measurement of W boson production and triple gauge couplings at LEP II
… For the couplings in the model in which gauge invariance is realised linearly, the following results are obtained ... where the errors shown are statistical, systematic and theoretical respectively. All results show consistency with expectations from the Standard Model.
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Effective field theory of the electroweak sector
… anomalous couplings framework. In particular, gauge invariance makes possible the calculation of loop corrections. Furthermore, the issue of unitarity violation is shown to be irrelevant in an effective field theory. There are nine dimension-six operators which generate corrections to precision …
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Gluon propagator in classical color field of colliding hadrons and its implications for hadronic cross sections
… gluon propagator is modified. The corresponding gauge invariance condition of the propagator is derived and shown to be satisfied. The modified gluon propagator leads to a suppression of the minijet cross section due to the gg [rightwards arrow] gg sub-process in the small-x region. We show that …
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Perturbative Check of the Action and Energy Lattice Sum Rules
… checking the energy sum rule. Additionally, the gauge invariance of the expectation value of the Wilson loop up to next-to-leading order is proven. The possibility of restricting the expectation value of the action to one fixed time slice is discussed. The energy sum rule is checked …
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Topics in the theory of lie fields
… considerations of inhomogeneous Lorentz invariance and weak locality alone. The author derives a partial categorization of the wide variety of possible scalar Lie field structures and presents the simplest types of examples. A Lorentz-invariant representation of one of these examples is …
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Rapidity evolution of observables at high energies using the Gaussian truncation
… which is relatively crude and subtly breaks gauge invariance. To get around this, we can perform a gauge invariant truncation of this hierarchy in the form of the Gaussian truncation for the correlators of these Wilson lines. Initial comparison to HERA data for the total and rapidity gap …
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Exploring strongly interacting gapless states : cuprates, pair density waves, and fluctuating superconductivity
… motion of the condensate plays a key role; gauge invariance guides us to the correct result. From Chapter 3 to Chapter 7, we construct a pseudogap metallic state by considering quantum fluctuating PDW. We analyze a recent scanning tunneling microscope (STM) discovery of period-8 density …
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Accurate Prediction of Chiroptical Properties
… we have begun the process of implementing a gauge invariant version of coupled cluster response properties to address the fundamentally unphysical lack of gauge invariance in coupled cluster optical rotations. Correcting this problem, which arises from the non- variational nature of the …
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Vector fields during cosmic inflation: stability analysis and phenomenological signatures.
… is explicitly proven that for models where the gauge invariance of the vector field is broken, the background solution is unstable. The proof is performed both (1) by studying the quadratic action for the fluctuations, and showing that ghost instabilities are present in the model and (2) by …
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Fluid and gas models in FLRW and almost FLRW universes
… models and perturbations thereof, leading to Gauge Invariant Covariant (GIC) perturbations of these fluid models. It is well known that kinetic theory provides a physically sound and consistent description of the matter and radiation in the universe, so a perturbative theory of gas models …
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Electromagnetic Form Factors of Hadrons in the Space-Like Region
… is also studied in detail. Constraints from gauge invariance are used to argue that the current model used to extract the pion form factor may be too simplistic. We study the model dependence in the context of a simple toy model, and nd that the possible errors associated with this …
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Perturbations and symmetry in gravitational theories : wormholes, wave dynamics, and quantum effects in rotating spacetimes.
… rotating space-times. The central thesis is that gauge invariance and geometric symmetry provide a unifying language for identifying physical degrees of freedom, distinguishing observables from coordinate artifacts, and organizing wave dynamics in classical and quantum regimes. Part I establishes …
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Well-posedness and scattering of the Chern-Simons-Schrödinger system
… the Chern-Simons-Schrödinger system, which is a gauge-covariant Schrödinger system in two spatial dimensions with a long-range electromagnetic field. The present thesis studies two aspects of the system: that of well-posedness and that of the long-time behaviour. The first main result of the …
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Diffraction in electron-proton collisions
… production it violates electromagnetic gauge invariance. We suggest a prescription to deal with this problem and compare the results we then obtain with those of the Landshoff-Nachtmann model. We find remarkable similarities between the two models, but they also show important …
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High-precision QED calculations of the hyperfine structure in hydrogen and transition rates in multicharged ions
… which has to be accounted for preserving gauge invariance. One-loop QED corrections to the magnetic-dipole transition amplitude between the fine-structure levels 2p_{3/2} and 2p_{1/2} are calculated to all orders in \alpha Z. Taking into account consistently relativistic, …
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Expanding the Toolkit for Optical Rotation Calculations: Development of Interpretive Models and Extension to Solid State Systems
… test of molecules in both the modified velocity gauge (MVG) and length gauge (LG) in order to determine how the physical interpretation provided by \st[] analysis is affected by the gauge. We found that the distribution of \st[] contributions was consistent across different gauges. The \st[] …
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