Cosmic Decoherence: Massive Fields

Understand

We study the decoherence of massive fields during inflation based on the Zurek's density matrix approach.

• With the cubic interaction between inflaton and massive fields, the reduced density matrix for the massive fields can be calculated in the Schr\"odinger picture which is related to the variance of the non-Gaussian exponent in the wave functional.
• The decoherence rate is computed in the one-loop form from functional integration.
• For heavy fields with $m\gtrsim \mathcal{O}(H)$, quantum fluctuations will easily stay in the quantum state and decoherence is unlikely.