Electroweak Baryogenesis in the Minimal Supersymmetric Standard Model

I describe work done in collaboration with M. Joyce and K. Kainulainen on (1) the strength of the electroweak phase transition in the MSSM and (2) the mechanism for producing the baryon asymmetry during the phase transition. In the former we compare the effective potential and dimensional reduction methods for describing the phase transition and search the parameter space of the MSSM for those values where it is strong enough. In the latter we give a systematic computation of the baryon asymmetry due the CP-violating force acting on charginos in the vicinity of the bubble wall. We find that a light right-handed stop, a light Higgs boson, and a large phase in the mu parameter, are the main necessary ingredients for producing the baryon asymmetry.Comment: 5 pages, Latex; Talk given at the Eotvos Conference in Science, Strong and Electroweak Matter '97, Eger, Hungary, 21-25 May 1997; and at the 19th Annual MRST (Montreal-Rochester-Syracuse-Toronto) High-energy Theory Meeting, Syracuse, New York, 12-13 May 199

Tachyon Defect Formation and Reheating in Brane-Antibrane Inflation

We study analytically the dynamical formation of lower dimensional branes at the endpoint of brane-antibrane inflation through the condensation of topological defects of the tachyon field which describes the instability of the initial state. We then use this information to quantify the efficiency of the reheating which is due to the coupling of time dependent tachyon background to massless gauge fields which will be localized on the final state branes. We improve upon previous estimates indicating that this can be an efficient reheating mechanism for observers on the brane.Comment: 9 pages. Talk given at the 26th annual Montreal-Rochester-Syracuse-Toronto Conference on High-Energy Physics: MRST 200

Supersymmetric Electroweak Baryogenesis in the WKB approximation

We calculate the baryon asymmetry generated at the electroweak phase transition in the minimal supersymmetric standard model, treating the particles in a WKB approximation in the bubble wall background. A set of diffusion equations for the particle species relevant to baryon generation, including source terms arising from the CP violation associated with the complex phase $\delta$ of the $\mu$ parameter, are derived from Boltzmann equations, and solved. The conclusion is that $\delta$ must be \gsim 0.1 to generate a baryon asymmetry consistent with nucleosynthesis. We compare our results to several other recent computations of the effect, arguing that some are overestimates.Comment: 12 pages, 1 figure, corrected some criticisms of hep-ph/9702409; to appear in Phys. Lett.

Status of Electroweak Phase Transition and Baryogenesis

I review recent progress on the electroweak phase transition and baryogenesis, focusing on the minimal supersymmetric standard model as the source of new physics.Comment: 10 pp, 6 figures; plenary talk given at 6th Workshop on High Energy Physics Phenomenology, 4 Jan. 2000, Chennai, India. v.2: added reference

One hundred angstrom niobium wire

Composite of fine niobium wires in copper is used to study the size and proximity effects of a superconductor in a normal matrix. The niobium rod was drawn to a 100 angstrom diameter wire on a copper tubing

An optimistic CoGeNT analysis

Inspired by a recently proposed model of millicharged atomic dark matter (MADM), we analyze several classes of light dark matter models with respect to CoGeNT modulated and unmodulated data, and constraints from CDMS, XENON10 and XENON100. After removing the surface contaminated events from the original CoGeNT data set, we find an acceptable fit to all these data (but with the modulating part of the signal making a statistically small contribution), using somewhat relaxed assumptions about the response of the null experiments at low recoil energies, and postulating an unknown modulating background in the CoGeNT data at recoil energies above 1.5 keVee. We compare the fits of MADM---an example of inelastic magnetic dark matter---to those of standard elastically and inelastically scattering light WIMPs (eDM and iDM). The iDM model gives the best fit, with MADM close behind. The dark matter interpretation of the DAMA annual modulation cannot be made compatible with these results however. We find that the inclusion of a tidal debris component in the dark matter phase space distribution improves the fits or helps to relieve tension with XENON constraints.Comment: 16 pages, 11 figures; v2: added discussion of dipole-dipole scattering and details of matrix elements; also implications of XENON100 2012 limits. Qualitative conclusions unchanged. Published versio

Recent Progress in Baryogenesis

I give a synopsis, specifically aimed at nonexperts, of some of the recent developments in electroweak baryogenesis. The focus of the talk is on the present status of electroweak baryogenesis in supersymmetric models, since this is a plausible and realistic possibility that is currently being probed by experimental searches for the Higgs boson and the top squark. The question of whether it is viable to have a period of color-breaking during the electroweak phase transition is also discussed