Physics and Astronomy Thesis Defense - Sam Cormack - Dartmouth College

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Physics and Astronomy Thesis Defense - Sam Cormack - Dartmouth College

Title: "Cosmological Applications of Scalar Fields"

Thursday, April 27, 2017
2:00pm-3:00pm
Wilder 111
Intended Audience(s): Public
Categories: Lectures & Seminars

Abstract: Scalar fields play an important role in modeling cosmological phenomena. They are used in models of inflation, dark matter and dark energy. We present three cosmological models involving scalar fields: a reheating model, a cyclic universe, and a model of superfluid dark matter. Our model of reheating has an axion-like inflation coupled to gravitational waves by a Chern-Simons term. Oscillation of the inflation at the end of inflation causes oscillation of gravitational waves which in turn drive parametric amplification of matter. Our cyclic universe gives an explanation of why the coupling constants in our universe take the values they do. The cycle of expansion, contraction and bounces is driven by an unusual scalar field with negative kinetic energy, known as a ghost field. This ghost field also sets the values of the coupling constants which change from cycle to cycle. Finally, we construct a model of superfluid fermionic dark matter. The scalar field here is not fundamental, rather, it is generated by the Bardeen-Cooper-Schrieffer condensation of Cooper pairs of fermions. We consider what effects this condensate may have on dark matter halos.

 
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Tressena Manning
603-646-2854

Events are free and open to the public unless otherwise noted.