Explaining the origin of the excess of matter over antimatter is one of the outstanding challenges lying at the interface of particle and nuclear physics with cosmology. It is generally believed that inflation resulted in a universe that was matter-antimatter symmetric. If so, then the particle physics of the subsequently evolving universe must have generated the net excess of baryonic matter that makes up the atomic nuclei in stars, planets, and human life itself. The process whereby this matter generation took place is called baryogenesis, and it is a central component of NPAC theory research.

In short, what we would like to explain is: How did something arise from nothing? Four decades ago, the Nobel laureate Andrei Sakharov identified three ingredients that must have been present in the particle physics of the early universe to lead to successful baryogenesis: violation of total baryon number (B); violation of both charge conjugation (C) and the combined charge conjugation-parity (CP) symmetries; and a departure from thermal equilibrium. In principle, the standard model of elementary particle physics contains all of these ingredients, but they are not present with sufficient effectiveness to produce the observed abundance of baryonic matter. Consequently, we must look to physics beyond the standard model in order to find a successful baryogenesis mechanism.

Our research on this problem involves several components: developing the theoretical tools needed to be able to compute the cosmic baryon asymmetry in a reliable way; delineating the ways future experiments may test various scenarios for baryogenesis; and identifying the most viable baryogenesis scenarios among the possible candidates for the “new” standard model of fundamental interactions. Our present focus is on electroweak baryogenesis, wherein the baryon asymmetry was generated when the universe was roughly 10^-11 seconds old. Searches for the Higgs boson at the Large Hadron Collider may tell us whether the universe underwent a phase transition at this time and, if so, whether the departure from equilibrium was sufficiently strong for baryogenesis. In addition, new searches for the permanent electric dipole moments of the neutron, electron, and neutral atoms may uncover the necessary CP-violation. 

The theoretical methods we apply to analyzing these phenomena and their implications for baryogenesis include non-equilibrium quantum field theory, finite temperature quantum field theory, non-perturbative Quantum Chromodynamics, and many-body theory. We are applying these methods to both supersymmetric and non-supersymmetric candidates for the new standard model.