Event

Using a combination of techniques spanning the modern amplitudes program, string theory, effective field theory, cosmology, and particle physics, I will show how the space of the possibilities for new physics can be constrained—from both top-down and bottom-up perspectives—in a variety of contexts, ranging from quantum gravity, to predictions for colliders, to cosmic inflation.

In the first part of the talk, we will ask a bedrock question of quantum gravity: Is string theory unique? String amplitudes famously accomplish several extraordinary and interrelated mathematical feats, including an infinite spin tower, tame UV behavior, and dual resonance. I will demonstrate that it is possible to construct infinite new classes of tree-level, dual resonant amplitudes with customizable, nonlinear mass spectra. The construction generalizes naturally to n-point scattering and allows for a worldsheet integral representation. However, these constructions can be strongly constrained using multiparticle factorization, which provides a powerful new set of tools for building consistent amplitudes. In the case of a Regge spectrum, I will investigate whether string amplitudes can be bootstrapped from first principles, finding extra freedom in the dynamics that allows for a new class of dual resonant hypergeometric amplitudes.

In the second part of the talk, I will take a particle physics-driven approach, constraining effective field theories using unitarity and causality. I will construct analytic dispersion relations for the effective field theory of the standard model, bounding the size and sign of higher-dimension operators, with significant implications for CP and flavor violation. These positivity bounds allow us to connect qualitatively different experiments, including predictions for the LHC and precision measurements. I will then apply these tools in a cosmological context, building positivity bounds for the theory of multifield inflation and extracting predictions for non-Gaussianities in the cosmic microwave background. 

Taken together, these two complementary initiatives comprise a program unifying phenomenological, formal, and cosmological approaches to high energy physics, bringing together powerful tools bridging fields to map the possibilities of future physics.