Quantum fluctuations and particle production in the oscillatory phase of a thermal inflaton in a FRW universe

Abstract

By the use of coherent and squeezed thermal states formalism, we analyzed the phenomena of particle creation when coherently oscillating a homogeneous scalar field (Inflaton) in semi-classical gravity. We also obtained an estimated solution for the semi-classical Einstein equation in non-classical thermal states formalism perturbatively, which is similar to the power-law expansion of classical Einstein equation. This solution, apart from a particular condition, shows oscillatory behavior in nature. We also analyzed a coherently oscillating homogeneous scalar field, in a thermal vacuum, coherent thermal, squeezed thermal vacuum and coherent squeezed thermal states, suffering from particle creation, and created particles are showing oscillatory behavior. Particle production can be raised due to thermal and quantum effects. We also studied quantum fluctuations of a homogeneous scalar field in the above-mentioned non-classical thermal states.

Squeezed Thermal State Representation of the Inflaton and Particle Production in Bianchi type-I Universe

“…Hence it can be concluded that, evolution of the cosmic scale factors are related mutually. If we put Z 1 (t) = Z 2 (t) = Z 3 (t)=Z(t), then the corresponding result reduces into the FRW model [62]. A damping process play an important role in the transformation from anisotropic to isotropic model.…”

“…Thermal counterparts of coherent and squeezed states are recognized as a coherent thermal state [49][50][51][52][53][54] and squeezed thermal state [50,51,[55][56][57][58]. Thermal properties of the nonclassical states play an important role to understand the thermal history and evolution of the early-stage universe [59][60][61][62][63][64][65]. According to cosmological perspective, consideration of thermal effects in flat FRW universe has many significance.…”