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 149 for “"Quantum field theory"”.
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Fractional quantum field theory
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-03-28 without embargo terms
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TOPICS IN QUANTUM FIELD THEORY
… to the change in the zero point energy of the theory due to the presence of a non-vanishing background field. The one loop term is carefully evaluated in Euclidean space, and the positivity of the one-loop eigenvalues is related to classical stability in terms of energy minimality. The case of …
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Making and remaking quantum field theory
… thesis, I examine two episodes in the history of quantum field theory using different research techniques and historiographic approaches. The first episode occurred during the 1920's and 1930's when quantum mechanics and relativity were being reconciled. I present some of the central developments …
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Topics in quantum field theory and holography
… theories to linearized order. The bulk theory we derive is consistent with the known AdS/CFT framework, and gives a concrete boundary to bulk implementation of AdS/CFT as a geometrization of the renormalization group.
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Worldsheet methods for perturbative quantum field theory
… prefactor; matching this amplitude to the field theory expectation in a particular kinematical regime; solving the one loop scattering equations in this kinematical regime; a conjecture for the IR behaviour of the one-loop ambitwistor integrand; computing the four graviton, two-loop …
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Quantum field theory of scalar cosmological perturbations
Using canonical quantization we show that the spectrum of the scalar cosmological fluctuations as calculated until now is not correct. We derive the correct expression for the spectrum, and show that our correct treatment alleviates the fine-tuning problem in inflation.
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'Variational' optimization in quantum field theory
We examine two different techniques for studying quantum field theories in which a 'variational' optimization of parameters plays a crucial role. In the context of the O(N)-symmetric $\lambda\phi\sp4$ theory we discuss variational calculations of the effective potential that go beyond the Gaussian …
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Enumerating Graphs Using Integrals From Quantum Field Theory
<p>Enumerating graphs is a relatively new subfield of mathematics. In this thesis, we will discuss a enumerative method that derives from Quantum Field Theory. We begin with the basic ideas of Calculus and extend them into a enumerative method that will allow us to classify graphs embedded on …
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Microcanonical simulations in classical and quantum field theory
… method for higher dimensional fermionic quantum systems. In the second part of this thesis, a numerical simulation of the evolution of a network of global cosmic strings in an expanding Robertson-Walker universe is carried out. The system is quenched through an order-disorder phase …
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Fermion Quantum Field Theory In Black-hole Spacetimes
The need to construct a fermion quantum field theory in black-hole spacetimes is an acute one. The study of gravitational collapse necessitates the need of such. In this dissertation, we construct the theory of free fermions living on the static Schwarzschild black-hole and the rotating Kerr …
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Tensorial spacetime geometries and background-independent quantum field theory
… this geometry that serious that our fundamental theory of matter, the standard model of particle physics, is based on it. However, it seems that there is a gap in our understanding if it comes to the physics outside of the solar system. Independent surveys show that we need concepts like dark …
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Aspects of quantum field theory, holography and de Sitter
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-02-04 without embargo terms
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Entanglement and Chaos in Quantum Field Theory and Gravity
… explore several questions at the intersection of quantum information theory and quantum many-body physics. We study properties like entanglement and chaos, and we use intuition from discrete, few-body systems to learn about continuum systems. First we study quantum scars, a phenomenon previously …
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Infinite Sets of Conserved Charges and Duality in Quantum Field Theory
… statistical mechanical system and an associated quantum Hamiltonian, using as an example the familiar two- 4 dimensional Ising model. Next, in chapter III, I show how this applies to Baxter's 8-vertex model and the XYZ Hamiltonian, and how an infinite set of conserved charges for the XYZ model …
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The effects of instantons in a finite temperature quantum field theory
… methods for investigating a SU(2) Yang-Mills theory at finite temperature. We first begin with a review of tunneling in a one-dimensional periodic potential. Here we introduce the methods of Euclidean path integrals and the idea of an instanton. Next we proceed to review Yang-Mills' theory at …
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Applications of modular inclusions in quantum field theory and quantum gravity
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-08-01
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A quantum field theory for the interaction of pions and rhos
We extend the Kroll-Lee-Zumino model in its particle content to include the charged rho vector mesons and the neutral pion meson. This entailed using the larger SU(2) gauge group. The masses for the vector mesons were generated via spontaneous symmetry breaking using the Higgs mechanism. The …
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Counting degrees of freedom in quantum field theory using entanglement entropy
… to define the number of degrees of freedom in quantum field theory. Intuitively, the number of degrees of freedom should decrease along the renormalization group (RG) flow, and should be independent of the RG scale at a conformal fixed point. We argue that a refinement of entanglement entropy …
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