Summer 2014 Seminar Series

Organizer: Dietrich Belitz

Seminars are at 4pm, Tuesdays, in 472 Willamette Hall and are preceded by cookies at 3:45.

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June 17, 2014 Predictions From High Scale Mixing Unification Hypothesis
Rahul Srivastava
Institute of Mathematical Sciences, Chennai

Starting with 'High Scale Mixing Unification' hypothesis, we investigate the renormalization group evolution of mixing parameters and masses for both Dirac and Majorana type neutrinos. Following this hypothesis, the PMNS mixing parameters are taken to be identical to the CKM ones at a unifying high scale. Then, they are evolved to a low scale using MSSM renormalization-group equations. For both type of neutrinos, the renormalization group evolution “naturally” results in a non-zero and small value of leptonic mixing angle θ_{13}. One of the important
predictions of this analysis is the prediction for octant of the mixing angle θ_{23}. We also elaborate on the important differences between Dirac and Majorana neutrinos within our framework and how to experimentally distinguish between the two scenarios. Furthermore, for both cases, we also derive constraints on the allowed parameter range for the SUSY breaking and unification scales, for which this hypothesis works. The results are novel and can be tested by present and future experiments.
N. Deshpande
June 24, 2014 The Graceful Exit Problem in Cosmology
Florian Beyer
University of Otago, New Zealand
Department of Mathematics & Statistics

According to the successful standard model of cosmology, the universe underwent a rapid phase of accelerated expansion, called inflation, just after the big bang. This phase, however, was over already after a short time and was succeeded by a long phase where the gravitational attraction between bodies led to decelerated expansion. The transition from accelerated to decelerated expansion is often referred to as the "graceful exit from inflation". In this talk, we consider the dynamics of certain classes of inflationary cosmological models. We ask under which conditions the graceful exit paradigm holds and present new results.
J. Isenberg
July 9, 2014 Cosmological Phase Transitions and their Properties in the NMSSM
Jonathan Kozaczuk

In this talk, I will discuss recent work studying
cosmological phase transitions in the Next-to-Minimal Supersymmetric
Standard Model (NMSSM) in light of the Higgs discovery. An effective
field theory approach is used to calculate the finite temperature
effective potential, focusing on regions with significant tree-level
contributions to the Higgs mass, a viable neutralino dark matter
candidate, 1-2 TeV stops, and with the remaining particle spectrum
compatible with current LHC searches and results. The phase transition
structure in viable regions of parameter space exhibits a rich
phenomenology, potentially giving rise to one- or two-step first order
phase transitions in the singlet and/or $SU(2)$ directions. I will also
discuss results for several parameters relevant for calculating the
baryon asymmetry in the context of electroweak baryogenesis, including
the bubble wall width, the bubble wall velocity, and $Δβ$, the
variation of the Higgs vacuum expectation values across the wall. Our
results suggest that successful electroweak baryogenesis may indeed
occur in regions of the NMSSM compatible with the Higgs discovery.
Spencer Chang
Last modified: Fr Aug 27 17:54:31 PDT 2010
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