Constructing a Wilsonian Cosmological Effective Action

Abstract

[evdate 2011-06-01] IAS Conference on Cosmology since Einstein. IAS title: Talk 19: 'Constructing a Wilsonian Cosmological Effective Action'.

Abstract: Wilsonian effective actions always presume energy conservation. This prevents a straightforward application to cosmological and other non‐equilibrium time‐dependent backgrounds. Prof Schalm argues that late‐time expectation values computed directly in the Schwinger‐Keldysh approach should not suffer from any complications as opposed to transition amplitudes computed in the standard path‐integral. He gives an explicit example by integrating out a heavy‐field in a Schwinger‐Keldysh model and shows that novel terms are generated that modify the density matrix. These non‐adiabatic terms can be interpreted as generating effective low‐energy boundary conditions at the New‐Physics Hypersurface. The physics interpretation is the production of heavy particles at threshold. Applying this formalism to slow‐roll inflation we find that the power spectrum is universally modified at order $H/M$, where $H$ is the scale of inflation. This ratio is optimistically estimated to be $10^{‐2}$, a precision obtainable by upcoming experiments.

Duration: 25 min.