Effective Field Theory for Inflation

Understand

The methods of effective field theory are used to study generic theories of inflation with a single inflaton field.

• For scalar modes, the leading corrections to the ${\cal R}$ correlation function are found to be purely of the $k$-inflation type.
• For tensor modes the leading corrections to the correlation function arise from terms in the action that are quadratic in the curvature, including a parity-violating term that makes the propagation of these modes depend on their helicity.
• These methods are also briefly applied to non-generic theories of inflation with an extra shift symmetry, as in so-called ghost inflation.