Matthew G. Sexton | Searcharxiv

arXiv2009

The evolution and decay of supersymmetric flat directions in the early universe and their role in thermalizing the universe

I study the post-inflation oscillation and decay of light coherent scalar field condensates that may develop during an inflationary phase of the universe. In particular, the light scalars studied are a composition of the scalar particles of a supersymmetric theory which correspond to the flat directions of the theory's scalar potential. Some toy models that possess supersymmetric flat directions are presented and numerical solutions for the evolution of the scalar fields are obtained. Both analytic and numeric results suggest that such condensates, if they existed in the early universe, can decay through a rapid and nonperturbative process long before these condensates could significantly affect the thermalization of the universe.

hep-ph↗

arXiv1998

Force distribution in a scalar model for non-cohesive granular material

We study a scalar lattice model for inter-grain forces in static, non-cohesive, granular materials, obtaining two primary results. (i) The applied stress as a function of overall strain shows a power law dependence with a nontrivial exponent, which moreover varies with system geometry. (ii) Probability distributions for forces on individual grains appear Gaussian at all stages of compression, showing no evidence of exponential tails. With regard to both results, we identify correlations responsible for deviations from previously suggested theories.

cond-mat.soft↗