Generalized Galileons for Particle Physics and Cosmology

In this brief article, I summarize attempts with collaborators over the last couple of years to extend the Galileon idea in two important ways. I discuss the effective field theory construction arising from co-dimension greater than one flat branes embedded in a flat background - the multi-Galileons - and then describe symmetric covariant versions of the Galileons, more suitable for general cosmological applications. These generalized Galileons can be thought of as interesting four-dimensional field theories in their own rights, but the work described here may also make it easier to embed them into higher dimensional theories. I also briefly mention some intriguing properties, including freedom from ghosts and a non-renormalization theorem, that hint at possible applications in particle physics and cosmologyComment: 6 pages, parallel session talk delivered at the ICHEP 2012 conferenc

Making Baryons Below the Electroweak Scale

I describe a new way for baryogenesis to proceed, which evades many of the problems of GUT and electroweak scenarios. If the reheat temperature after inflation is below the electroweak scale, neither GUT baryon production nor traditional electroweak baryogenesis can occur. However, non-thermal production of sphaleron configurations via preheating could generate the observed baryon asymmetry of the universe. Such low scale baryon production is particularly attractive since it evades a number of strong constraints on reheating from gravitino and moduli production.Comment: 9 pages, uses RevTeX, to appear in the proceedings of COSMO-99, International Workshop on Particle Physics and the Early Univers

Dark Energy and Cosmology

Understanding the space of possible theoretical explanations for the observed cosmic acceleration is a central challenge of modern cosmology. This brief document sketches selected aspects of approaches to this problem, focusing on the possibility that a modification to General Relativity is responsible for acceleration, as presented as a plenary talk at the ICHEP 2012 conference.Comment: 11 pages, invited plenary presentation delivered at the ICHEP 2012 conference. arXiv admin note: text overlap with arXiv:1105.0721, arXiv:1011.0861, arXiv:astro-ph/060751

Dirichlet Solitons in Field Theories

I briefly describe a new class of soliton configurations in field theories. These consist of topological defects which can end when they intersect other defects of equal or higher dimensionality. Such configurations may be termed ``Dirichlet topological defects'', in analogy with the D-branes of string theory. I provide a specific example - cosmic strings that terminate on domain walls - and discuss some new directions for this work, including an interesting and qualitatively different extension to supersymmetric theories.Comment: 5 pages, to appear in the proceedings of COSMO-9

Theoretical Aspects of Cosmic Acceleration

Efforts to understand and map the possible explanations for the late time acceleration of the universe have led to a broad range of suggestions, ranging from the cosmological constant and straightforward dark energy, to exotically coupled models, to infrared modifications of General Relativity. If we are to uncover which, if any, of these approaches might provide a serious answer to the problem, it is crucial to understand the constraints that theoretical consistency places on the models, and on the regimes in which they make predictions. In this talk, delivered as an invited plenary lecture at the Dark Side of the Universe conference in Kyoto, Japan, I briefly describe some modern attempts to carry out this program and some of the more interesting ideas that have emerged. As an example, I use the Galileon model, discussing how the Vainshtein mechanism occurs, and how a number of these theoretical problems arise around such backgrounds.Comment: 14 pages, 5 figures. Invited plenary talk at the Dark Side of the Universe conference, Kyoto, Japan, December 2015. To appear in the proceeding