The Origin of Matter in the Universe: Nonequilibrium Field Theory and Inflationary Cosmology

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One of the greatest challenges of modern cosmology and particle physics is to explain the origin of matter in the Universe. How did the matter that makes galaxies, stars, and ultimately living beings originate in the primeval fireball described by the Big Bang model? Once the ingredients are there the leptons, quarks, and gauge fields comprising the Standard Model of particle physics Big Bang cosmology is very successful at explaining the formation of the first light nuclei and atoms. The challenge lies in understanding the mechanisms responsible for generating the particles of the Standard Model themselves: their origin and the ubiquitous excess of matter over antimatter. Observations firmly support the notion that the early Universe underwent a short period of superluminal (exponential) expansion known as inflation. The origin of matter is traced to the end of this inflationary era, when the primordial field that drives inflation transfers its energy into matter fields. This transfer is dramatic: it effectively models the hot Big Bang and is believed to have occurred in at least two phases, known as preheating and reheating. The goal of this proposal is to address both the origin of matter and its excess over antimatter as inflation transitions into the hot Big Bang model. The PI plans to analyze in detail the nonperturbative dynamics of the preheating and reheating stages for a variety of models, using analytical and numerical techniques of nonequilibrium field theory. Based on this analysis, the PI hopes to propose several observational consequences of pre/reheating for different models, including: the number of e-folds or efficacy of the inflationary phase; the generation of net baryon number; and the production of a stochastic background of gravitational waves.