Theoretical Nuclear, Particle, Astrophysics, and Cosmology (NPAC)
Bjorn Garbrecht
email address: bjorn@physics.wisc.edu
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Research: I conduct research on particle physics and cosmology. In particular, I am interested in models which link observational signatures such as the baryon (matter-antimatter) asymmetry of the Universe, temperature anisotropies in the Cosmic Microwave Background and of course earth-based particle physics experiments. My current work with D J Chung, M J Ramsey-Musolf and S M Tulin on baryogenesis is focussed on the mechanism of Electroweak baryogenesis. With T Prokopec and M G Schmidt, I have also proposed the possibility of creating the baryon asymmetry directly through preheating after a phase transition. With C Pallis and A Pilaftsis, I have constructed the so called F_D-model, a viable cosmological scenario invoking features such as hybrid-inflation, resonant leptogenesis, TeV-scale right-handed neutrinos and low-energy supersymmetry. It is an example for a complete cosmological scenario which will be testable by collider and astrophysical observations in the near future. The presently available WMAP-data on the Cosmic Microwave Background radiation slightly favours a subdominant contribution of cosmic strings as a source for the temperature anisotropy, which has been pointed out by R Battye, A Moss and myself. Furthermore, the presence cosmic strings alters the best-fit values of other cosmological parameters, with consequences for constraints on models of cosmic inflation. Another of my interests is quantum theory in curved space-times, to a large extent pursued with T Prokopec. Because of its large degree of symmetry and of its relevance for inflationary models, de Sitter space is an interesting arena for studies. We have found that massless fermions interacting with a scalar field pick up an effective mass term without breaking chiral symmetry, similar to the situation in thermal field theory. Furthermore, we have proposed a new mechanism for baryogenesis, driven by inflation. I have also studied the impact of the space-time curvature on flat directions of the Minimal Supersymmetric Standard Model during inflation. Recent Papers:
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My home page is: http://www.physics.wisc.edu/people/staff/bgarbrecht/
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