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Cosmology Talks

This series consists of discussions in the areas of Cosmology and Particle Physics.

Seminar Series Events/Videos

Currently there are no upcoming talks in this series.

 

Tuesday Sep 06, 2011
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I will discuss the phenomenologically interesting scenario of matter inflation in supersymmetric hybrid inflation models. The inflaton resides in a gauge non-singlet matter multiplet and the eta-problem is solved by a "Heisenberg" symmetry. This symmetry relates the inflaton with a modulus field and we stabilize this modulus via corrections to the Kähler potential. The Heisenberg symmetry arises naturally for the untwisted matter fields in heterotic orbifolds.

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Wednesday Aug 24, 2011
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I'll discuss my recent results (1108.2255) showing that, once gravity and some technical confusions are taken care of, two classes of potentials one expects to be generic in a landscape, namely ones resulting in thin-wall instantons or with small relative differences in potentials, result in instantons which typically decay rapidly, including exponentially enhanced rates for thin-wall instantons. I'll explain why this is true both generally and in detail and why the previous treatments have gone astray.

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Thursday Feb 10, 2011
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In terms of their energetics, cosmic ray protons are an insignificant by-product of star formation and super-massive black hole growth. However, due to their small mean free path, their coupling with the interstellar medium is absolute. In fact, they are most likely, the dominant source of momentum, and therefore kinetic force on galactic scales. By defining an Eddington Limit in Cosmic Rays, we show that the maximum photon luminosity of bright galaxies and quasars are capped by the production and subsequent expulsion of cosmic ray protons.

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Friday Feb 04, 2011
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The resonant tunneling phenomenon is well understood in quantum mechanics. I argue why a similar phenomenon must be present in quantum field theory. Using the functional Schr\"odinger method I show how resonant tunneling through multiple barriers takes place in quantum field theory with a single scalar field. I also show how this phenomenon in scalar quantum field theory can lead to an exponential enhancement of the single-barrier tunneling rate. My analysis is carried out in the thin-wall approximation.

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Tuesday Jan 18, 2011
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Strong lensing galaxy clusters provide promising probes of cosmological structure formation. Strong lensing halos can be identified in cosmological simulations through ray tracing techniques and their properties measured. Previous studies have found some evidence that strong lensing clusters are more concentrated than expected, with possible explanations including baryonic effects or more exotic physics such as early dark energy.

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