Master's project seminar: Matthew Smith

Title:
The Effective Field Theory of Chromo-Natural Inflation

Abstract:
This thesis explores cosmic inflation driven by an axion field coupled to non-Abelian gauge fields through a Chern-Simons term. By constructing the effective field theory for such a model, maintaining shift symmetry and limiting spacetime derivatives to four, we address the tension of cosmological observations with Chromo-natural (CNI) inflation. The modified effective Lagrangian introduces additional terms that resolve the tension while predicting a unique chiral gravitational wave spectrum. This work demonstrates how these terms allow for greater flexibility in reducing the tensor-to-scalar ratio while remaining within the latest bounds on the spectral index.