On the Expected Production of Gravitational Waves During Preheating

Understand

The existing predictions of the energy density of gravitational waves produced during preheating mostly rely on computer simulations in which the matter field inhomogeneities essentially behave classically.

• In this article we follow instead a full quantum treatment of the process within the $in$-$in$ formalism.
• We use this approach to determine the expected density of the produced gravitational waves and numerically estimate its value in a simple scalar field model, neglecting backreaction.
• Particular attention is devoted to the regularization and renormalization of the divergences that appear in the in-in formalism.