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 17 of 17 for “"Lorentz Invariance"”.
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Topics on electron,neutrino and axion scattering
… in this thesis we particularly investigate Lorentz invariance using Compton Scattering at the Compton Polarimeter located in Hall-C at Thomas Jefferson National Accelerator Facility. The Mississippi State Axion Search, an axion search experiment which uses light shining through a wall …
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Aspects of holography in Lorentz-violating gravity
… hence, on the equivalence principle and local Lorentz invariance.</p><p>The goal of this dissertation is to re-evaluate this generally accepted wisdom. To that end, we consider a modified gravity theory called Einstein-aether theory. This theory violates local Lorentz invariance and therefore …
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Topics in the theory of lie fields
… by the algebraic 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 …
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Symmetries, unitarity and positivity of cosmological effective field theories
… spontaneously breaks time translation and Lorentz boost invariance. Thus the usual tools of particle physics, which assume full Lorentz invariance, need to be adapted to the study of cosmological theories. Using Effective Field Theory (EFT) techniques, universal predictions can be made …
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Effective Field Theories in Cosmology
… some basic tenets of General Relativity such as Lorentz invariance and the weak equivalence principle. We also employ effective field theory methods to explore the imprint that high energy physics can leave on the small departures from homogeneity and isotropy generated in the early universe.</p>
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Superstrings in Four Dimensions
… 26 spacetime dimensions, or else a breakdown of Lorentz invariance occurs. But it is not a fully consistent theory because it contains a tachyon (a particle with negative mass squared) in its spectrum and its amplitudes have infinities. The open (type I) as well as the closed (type II) …
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Physics from Time Variability of the VHE Blazar PKS 2155-304
… to date on limits for the violation of Lorentz invariance induced by quantum-gravity effects from AGN measurements.
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Vignettes in string theory : using geometry to probe the worldsheet and strongly coupled physics
… investigate sigma models that break world-volume Lorentz invariance. Specifically, we calculate the one loop beta function for a target space metric whose worldvolume scales space and time differently, with dynamical exponent z = 2. We find, as in the isotropic case, the beta function is …
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Constrained dynamics and higher derivative systems in modified gravity
… gravity, at the price of giving up the Lorentz invariance. In the second part of the thesis, we study the spherically symmetric static solution of a class of two scalar-field theory, where one of them is a Lagrange multiplier enforcing a constraint relating the value of the other scalar …
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Gravitational Waves and Inspiraling Compact Binaries in Alternative Theories of Gravity
… theories of gravity for violations of Lorentz invariance in gravitation, and investigate their impact on the propagation of gravitational waves. We show how such corrections map to the waveform observable by a gravitational-wave detector, and to the “parametrized post-Einsteinian …
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Silicon detector testing for neutron beta decay experiment nab
… the types of interactions are constrained by the Lorentz invariance of bi-linear covariants. Precision measurements of decay correlation parameters can be used to test standard model predictions. The Nab experiment at the spallation neutron source(SNS) Oakridge National Laboratory aims to measure …
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Investigation into compactifed dimensions : Casimir energies and phenomenological aspects.
… theory. In general, this ground state must obey Lorentz invariance, at least with regards to 3 spatial dimensions, meaning that the vacuum must look identical to all observers. At all energies probed by experiments to date, the universe is accurately described as a set of quantum fields. If we …
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The Phase of the Cosmological Wavefunction
… tree-level bispectra and show how diffeomorphism invariance links contact and exchange terms. Despite the complexity of bulk interactions, the resulting boundary correlators have a remarkably simple analytic structure, with poles only in the total energy. These results provide a complete …
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On the parallels between the Maxwell and Dirac equations
… wave, arising as a consequence of enforcing Lorentz invariance in the electronic Maxwell equations. The physical quantities described by these electronic fields closely parallel their electromagnetic counterparts. We also make a discussion on wave components we may measure if the matter wave …
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Invariant polynomials and machine learning
… momenta in collision events where our system is Lorentz- and permutation-invariant. In the latter, the vectors represent the positions of atoms in molecules (or lattices) where our systems are Euclidean- and permutation-invariant. We start by focusing on the algebras of invariant polynomials in …
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Topological insulators and semimetals in the presence of interactions
… and type-II WSMs, that additionally breaks Lorentz invariance. Using the Born approximation, we find that the Anderson disorder renormalizes the topological mass of the WSM. The renormalization of the topological mass induces a quantum phase transition from type-I WSMs to type-II WSMs. The …
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On the Variability of the Fine Structure Constant
This thesis addresses the issue of the time variability of the fine structure constant, alpha. Recent claims of a varying alpha are set against the established standards of quantum electrodynamical theory and experiments. A study of the feasibility of extracting data on the time dependence of alpha …