Theoretical Physics

This award funds the research activities of Professors Igor Klebanov, Simone Giombi, and Herman Verlinde at Princeton University. Quantum field theory, which unifies quantum mechanics with special relativity, is often described as the universal language of theoretical physics. In addition to elementary particles, field theory can describe critical phenomena, which occur near continuous phase transitions. The field theories describing critical phenomena often possess extra conformal symmetry which facilitates their study. Such theories, which are called conformal field theories, have been shown to possess alternate geometrical descriptions which involve general relativity. This remarkable “holographic” correspondence has led to important insights into quantum versions of Einstein’s theory of gravity and of string theory. This award will be used to apply these ideas to quantum models of black holes and cosmology, which should eventually build connections with quantum information theory. Furthermore, novel classes of critical phenomena will be investigated using the powerful apparatus of conformal field theory. As a result, research in this area advances the national interest by promoting the progress of science in one of its most fundamental directions: the discovery and understanding of new physical law. Graduate students and post-doctoral researchers will be essential to this research program; educating and mentoring them will constitute its key broader impact. At a more technical level, the research will include active exploration of quantum field theories in the presence of defects. New methods are being developed for studying interactions localized on defects or boundaries, which lead to novel types of critical phenomena and renormalization group flows. Some field theory and lattice models have non-Hermitian Hamiltonians, which are nevertheless protected by the so-called PT symmetry. The award will be used to study critical phenomena associated with the breaking of PT symmetry, which can be described by non-unitary conformal field theories. The research will continue exploration of the Anti-de Sitter/Conformal Field Theory correspondence, as well as the simpler version of holography involving large N matrix quantum mechanics. They can lead to deeper insights into the emergence of strings from large N quantum systems. Holographic correspondences will also be used to investigate black holes and cosmological spacetimes in lower dimensional models of quantum gravity. 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.