Symmetry Breaking Patterns for Inflation

Understand

We study inflationary models where the kinetic sector of the theory has a non-linearly realised symmetry which is broken by the inflationary potential.

• We distinguish between kinetic symmetries which non-linearly realise an internal or space-time group, and which yield a flat or curved scalar manifold.
• This classification leads to well-known inflationary models such as monomial inflation and $\alpha$-attractors, as well as a new model based on fixed couplings between a dilaton and many axions which non-linearly realises higher-dimensional conformal symmetries.
• In this model, inflation can be realised along the dilatonic direction, leading to a tensor-to-scalar ratio $r \sim 0.01$ and a spectral index $n_{s} \sim 0.975$.