Explorations in Early Universe Cosmology and Dark Matter

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This award funds the research activities of Professor Daniel Boyanovsky at the Department of Physics, University of Pittsburgh. Our understanding of the early and present Universe has been revolutionized by observations of the Cosmic Microwave Background and galaxies, supporting the main paradigm of inflationary cosmology: quantum-mechanical fluctuations of primordial origin seed the formation of galaxies. These observations, along with the discovery of the Higgs Boson and the experimental confirmation of the theory of strong and electroweak interactions, confirm the Standard Models of Cosmology and Particle Physics. Along with these discoveries new challenging aspects emerge: 95% of the energy density in the Universe is in the form of Dark Matter and Dark Energy. Furthermore, neutrinos, the most elusive particles in nature, are found to be massive and undergo mixing and oscillations among the different types --- a phenomenon beyond the Standard Model. These discoveries bring an unprecedented convergence of particle physics, astrophysics, and cosmology in which observations of galaxies along with accelerator and reactor experiments will yield insights beyond the Standard Models, with the tantalizing possibility that a new species of neutrinos may explain Dark Matter. Professor Boyanovsky's research program seeks a fundamental understanding on two fronts: (i) the production and properties of a new species of neutrinos as possible Dark-Matter candidates, and (ii) a firmer assessment of the quantum fluctuations generated in the primordial Universe that ultimately seed the formation of galaxies. The program is at the forefront of particle astrophysics and cosmology, complements robust experimental and observational efforts, and is truly interdisciplinary as it implements methods from other fields in physics. Research in these areas thus advances the national interest by promoting the progress of science in one of the most fundamental and stimulating endeavors of deep intellectual merit: the discovery of novel phenomena and the understanding of the evolution of our Universe and the origin of galaxies beginning from the smallest constituents. Through this cross-fertilization of concepts and methods, this research program also provides students with a broader perspective and unique opportunity to acquire a truly interdisciplinary educational experience. Specifically, Professor Boyanovsky will study mechanisms for production, evolution, and gravitational clustering of new species of neutrinos during the early stages of the Early Universe by implementing methods from out-of-equilibrium quantum field theory and from quantum kinetics. These powerful methods will allow a systematic assessment of the new species of neutrinos as a Dark-Matter candidate. In cosmology, the program will focus on a deeper understanding of quantum processes and correlations during the inflationary stage in the early Universe. In particular, Professor Boyanovsky will study modifications of the spectrum of fluctuations from interactions and pre- and post-inflationary dynamics and their potential for detection with forthcoming observations. The study of processes during the period of rapid inflationary expansion requires novel tools. New methods based on concepts borrowed from quantum optics, such as quantum master equations, and out-of-equilibrium effective field theory, will provide a deeper and more fundamental assessment of possible observational consequences.