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 118 for “"early Universe"”.
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Cosmological Perturbations in the Early Universe
… to formation of large scale structures in the universe, relies on quantizing general relativity coupled to a scalar field. This is a system that respects diffeomorphism invariance, the freedom of choosing the coordinate system to work with without changing the physics. Hence the way to handle …
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Thermal particle production in the early universe
… particles via decay and scattering in the early universe which is in the state of a hot thermal plasma. Already at leading order in the gauge coupling constant multiple rescattering off soft (p ~ gT) gauge bosons has to be included which leads to nontrivial interference terms that must be …
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Large-scale structure of the early universe
The large-scale structure of the universe is one of the most active areas of research in modern astronomy. However, until recently our knowledge of the distribution of matter on large scales has been primarily limited to two epochs - the present epoch and the epoch of recombination - and …
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Probing hidden sectors with early universe cosmology
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2023-04-12 without embargo terms
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Causality and unitarity in the early universe
The early universe, with its high energy scales, provides a unique opportunity to explore new physics. Insights into this are encoded in the correlation functions of primordial perturbations, observable through the CMB and LSS anisotropies. To maximize these insights, it is essential to adapt tools …
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Dark matter dynamics in the early universe
We study a new form of dark matter interaction which may significantly affect the thermal relic abundance of dark matter. This new interaction takes the form C+D --> C+[phi], where D is the dark matter species present today, [phi] is a standard model species, and C is a very heavy exotic particle. …
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Hydrogen hyperfine studies of the early universe
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1998.
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Exotic Dark Matter in the Early Universe
… for its existence comes from its effects on early universe observables, perhaps clues to its fundamental nature also reside in its behavior in the early universe. In this thesis, I explore two scenarios in which dark matter is capable of exotic behavior in the early universe. In the first …
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Spacetime structure of the very early universe
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1985.
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Hunting Supermassive Black Holes in the Early Universe
… tightly correlated with host galaxies in local universe. Whether such relationship apply in the early universe remains debated, observation shows that active galactic nuclei, or quasars, already exist when the universe is less than 1 Gyr years old. This thesis focuses on using state-of-the-art …
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Dynamics in neutron stars and the early universe
"Observations of pulsar timing suggest that glitches and post-glitch behavior are due to variable coupling between the superfluid and normal components in neutron stars. A rotating superfluid is threaded by quantized vortex lines which, in the inner crust of a neutron star, can pin to the nuclear …
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Fundamental physics from observations of the early universe
… non-Gaussianity in the initial conditions of the Universe. Inhomogeneities in recombination and reionization amplify the perturbations in the underlying matter density and the resulting second order effects may be important. I calculate the bispectrum due to these second order effects and find …
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Effects of Massive Fields on the Early Universe
… tools to understand the physics that governs the universe at high energies. On one hand, inflation is a very robust mechanism to explain the initial conditions of the universe. On the other hand general relativity provides a solid framework for the formation of cosmic structures at cosmological …
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Gravitation and phase transitions in the early universe
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1982.
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Applications of particle physics to the early universe
In this thesis, I show some of the results of my research work in the field at the crossing between Cosmology and Particle Physics. The Cosmology of several models of the Physics Beyond the Standard Model is studied. These range from an inflationary model based on the condensation of a ghost-like …
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Early universe cosmology as a probe of fundamental physics
… background radiation supports the idea for an early phase of accelerated expansion called inflation. While the simplest inflationary models provide a consistent theoretical framework in explaining observational data, we are yet to understand the microscopic</p> <p>details of the inflationary …
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Gravitational waves and gauge fields in the early Universe
… inflation as the leading paradigm of the early Universe, the exact microphysics that realize inflation are poorly constrained. Moreover, inflation generically leaves the Universe cold and empty. The fundamental physics underlying reheating, the dynamics that transition the …
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Inhomogeneities in the early universe from the configuration space perspective
We develop a new technique of analyzing the dynamics of cosmological perturbations in the linear regime. The gist of our method, described in Chapters 2 and 3, is to solve the corresponding evolution equations in 1 + 1 space-time dimensions with the initial conditions proportional to a spatial …
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The quark-hadron transition and hot hadronic matter in the early universe
… of the evolution of the hadron gas in the early universe are carried out. To determine the starting point for the evolution equations a phase transition between the quark-gluon plasma phase and the hadron gas phase is constructed. A simple calculation leads to an estimate of the chemical …
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