Anomalies, String Vacua and the Swampland

This award funds the research activities of Professors Katrin Becker and Ergin Sezgin at Texas A&M University. String theory is a leading candidate for providing a framework that unifies the two pillars of our understanding of the laws of nature at the fundamental level, namely quantum theory and gravity. Its main premise is that all elementary particles in nature are different vibrations of an incredibly small fundamental string. Remarkably, the consistency of string theory requires extra dimensions, and the shape of these extra dimensions determines the spectrum of observed particles and the forces between them. For phenomena at low energies, string theory involves an extension of Einstein's theory of gravity, known as supergravity. As part of this research project, the PIs will explore fundamental aspects of string theory and supergravity. This is expected to enrich the interface between string theory and mathematics as well. This project advances the national interest by promoting the progress of science in the US and seeking new physical laws describing uncharted territories involving not only the extreme conditions that existed in the era of the early universe but also the black hole environment where the gravitational force is extremely large. The PIs will also provide critical training to postdocs and students. They also intend to give public lectures on their research results and organize workshops. More technically, Professors Becker and Sezgin aim to address moduli stabilization in type IIB string theory compactified on Gepner models. The goal is to determine if the shape and size of the extra dimensions of string theory, which in four space-time dimensions are described by fields called moduli fields, can be predicted. If successful, this will increase the predictive power of string theory and could open the door to answering questions such as determining why we live in four space-time dimensions or why there are three families or generations of quark and leptons among the elementary particles. Further, the PIs will study the higher derivative couplings of supergravity theories and their spontaneous compactifications. Moreover, the PIs will determine candidate effective theories of quantum gravity that can in principle admit a UV completion. They will also study the geometrical description of duality symmetries of strings and branes in a powerful framework known as exceptional field theory. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.