Quantum Field Theory and Cosmology

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The project involves a number of areas of collaborative research with N. Tsamis (U. of Crete), T. Prokopec (U. of Heidelberg), and the PI's graduate students in the general area of quantum field theoretic effects in cosmology . These include: (1) Comparing standard cosmological perturbation approximations with the exact solution recently obtained by the PI and Tsamis; (2) A method to calculate the effect of quantum gravity on inflation; (3) Developing a model in which the observed excess of matter over anti-matter is generated during inflation. (4) Computing what happens to the vacuum polarization induced by charged, massless scalar particles after the end of inflation; (5) Investigating whether a very slightly unstable, alternate theory of gravitation can be constructed which explains the motions of cosmological objects without the need for dark matter. (6) Expressing the vacuum polarization of charged massless scalar particles in terms of the natural geometrical objects during inflation; (7) Developing an improved formalism for computing quantum gravitational effects in a locally de Sitter-cosmology background. Problem (1) is relevant to the precision measurements of the cosmic microwave anisotropy by the WMAP satellite and the various missions planned for the future. Standard approximation techniques are almost certainly sufficient to compute the primordial spectrum from simple models of inflation but the exact result obtained by the PI and Tsamis may be very useful if an exotic model pertains. A successful outcome for problem (2) would completely change the paradigm of inflationary cosmology, resolving two of its major problems (why was the initial state homogeneous enough to begin inflating? and why is the observed cosmological constant so small?) and transforming it into a predictive theory. A successful outcome for problem (3) would resolve the long-standing conundrum that inflation tends to wipe out the excess of matter over anti-matter. Problem (4) should settle the issue of whether or not inflation provided the small but cosmological scale magnetic fields that served as the seeds of the fields we observe in present-day galaxies and galactic clusters. Problem (5) represents the last realistic hope for explaining cosmological motions using an alternate theory of gravitation rather than dark matter. Problems (6-7)represent incremental advances in formalism and good exercises for beginning graduate students.