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 12 of 12 for “"fine-structure constant"”.
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On the Variability of the Fine Structure Constant
… 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 using …
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Screening and the effective fine structure constant in graphene
… thesis discusses two main topics – the effective fine-structure constant of and dielectric screening in graphene, and a new coherent inelastic x-ray scattering technique for attosecond resolution imaging of excitations in crystalline materials. The strength of electron-electron interactions in …
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A sub-ppb measurement of the mass of cesium for a new determination of the fine-structure constant
… on the accuracy of a determination of the fine-structure constant alpha via a Cesium photon recoil experiment. Removal of this limit should ultimately allow this value of alpha to have a relative accuracy ~1 ppb, which would be comparable to or even better than the most accurate measurement …
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Quantum Interference Effects in Precision Spectroscopy of Helium Fine Structure
Precision spectroscopy of atomic helium fine structure provides a means of testing fundamental few-body theory as well as determining the fine-structure constant, which characterizes electromagnetic interactions in nature. Progress in both experiment and theory has led to increasingly precise …
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Motion in a scalar field
… to deliver high-precision measurements of the fine-structure constant. The vacuum chambers employed in these setups make them ideal testing grounds for a class of scalar--tensor theories that screen the effects of their scalar mode based on the ambient density. If unscreened, the scalar exerts …
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Trapping, laser cooling, and spectroscopy of Thorium IV
… metrology and tests of variation of fundamental constants. This work is a report on the development of required technologies to realize such a nuclear optical clock with a single, trapped, laser cooled ²²⁹Th³⁺ ion. Creation, trapping, laser cooling, and precision spectroscopy are developed and …
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Light-Matter Interactions with Photonic Quasiparticles
… parameters (e.g., field strength, atomic size, fine-structure constant). This understanding is challenged by recent experiments coupling light to collective electromagnetic excitations in solids ("photonic quasiparticles"), whose strongly confined electromagnetic fields can interact strongly …
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Radiative Corrections to and Connections Among Theories With Lorentz Violation and Time-Varying Couplings
… electromagnetic sector, a time-variation in the fine structure constant &alpha is studied as a possible mechanism to generate Lorentz, CPT and gauge symmetry violations in quantum electrodynamics. The vacuum polarization diagram and fermion self-energy are studied in order to study the …
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Manifestations of Dark Matter and Variations of the Fundamental Constants of Nature in Atoms and Astrophysical Phenomena
… or quadratic (g^2) in an underlying interaction constant g. In this thesis, I explore the possibility of searching for new effects of dark matter that are linear in g. Searching for linear effects of dark matter may provide an enormous advantage over conventional schemes, since the interaction …
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Long-range interatomic interactions: Oscillatory tails and hyperfine perturbations
… der Waals range (a₀ « R « a₀/α, where α is the fine structure constant), the intermediate or Casimir-Polder range (a₀/α « R « ħc/L, where L is the Lamb shift energy), and the very long or Lamb shift range (R » ħc/L). We also study the Dirac-<em>δ</em> perturbation potential acting on the …
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Self-adjoint extensions to the Dirac Coulomb Hamiltonian
… of protons in the atomic nucleus, a is the fine structure constant, m is the electron mass, c is the speed of light, and n a positive integer. Note that this formula assumes a stationary positive charge of infinite mass at the center of the atom, and that the energy levels for a more …
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Measurements and models of fine-structure, internal gravity waves and wave breaking in the deep ocean
… modes in the presence of temperature and density fine-structure. Two turning-point uniformly valid asymptotic solutions to the internal wave equation are developed to describe the wave functions. Mode decay beyond the turning point in depth or frequency produces a sharp cutoff in vertical current …