String Compactifications: From Geometry To Effective Field Theory

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This award funds the research activities of Professors Lara Anderson, James Gray, and Eric Sharpe at Virginia Tech.In string theory --- a proposal for a fundamental theory of quantum gravity --- the roles of physics and geometry are intrinsically intertwined. While the questions that string theory attempts to answer are physical, the path to those answers frequently leads to cutting-edge challenges in modern mathematics. This award will fund a collaborative program of research to explore the physics that arises from string compactifications. The goals of this work include strengthening the links between string theory and current progress in particle physics by developing new foundational tools for the subject of string phenomenology. In addition, Professors Anderson, Gray and Sharpe aim to further bound and characterize the geometries arising in string compactifications. Experience shows that when strong physical requirements are expressed in the language of geometry, they can open the door to new and unexpected results in both physics and mathematics. As a result, research in this area advances the national interest by promoting the progress of basic science. Professors Anderson, Gray and Sharpe will involve junior scientists in this project, including a postdoctoral researcher and several graduate students who will take part in the collaborative research. Their efforts will include the organizing of conferences and workshops that will increase dialog between physicists and mathematicians on pressing problems at the boundary of both fields. In all of these aspects of student training and professional dialog, Professors Anderson, Sharpe and Gray are committed to actively encouraging the inclusion of under-represented groups into the frontline of progress in the sciences. More specifically, the PIs will study two of the most flexible frameworks for four-dimensional compactifications of string theory: Heterotic string theory and F-theory. Within heterotic string theory, novel descriptions of the physical and geometric moduli spaces will be used to compute previously undetermined aspects of the effective theory, including the N=1 matter field Kahler potential and physically normalized Yukawa couplings. The nonperturbative contributions to Yukawa couplings will also be computed via quantum sheaf cohomology, a generalization of ordinary quantum cohomology. This work will explore new dualities including (0,2) mirror symmetry, as well as the global structure of the moduli space of SCFT's. Within F-theory, new results in the geometry of elliptic fibrations will be used to study the properties of singular Calabi-Yau manifolds and their links to Hitchin systems, as well as to study the implications of the ubiquity of multiply fibered manifolds for string dualities and effective theories. Recent progress in geometry will be used to extract new features of the effective theories describing F-theory compactifications, including the explicit four-dimensional field-dependent form of flux contributions to the superpotential.