Speaker
Description
An oscillating curvature of the spacetime can drive the production of dark matter during reheating, and accurately quantifying this requires the use of both non-perturbative and non-equilibrium methods. In our work, we compare the particle production on a non-minimally coupled scalar field when computed using a classical lattice approach to previous work utilizing Hartree-level 2PI-methods. Both approaches find two distinct phases of particle production, an initial tachyonic growth and a subsequent period of parametric resonance. In the range of scalar self-couplings considered, the lattice and the 2PI-approaches were also in agreement on average quantities such as the final scalar field variance up to a factor of less than 5. However, we also find that mode-mixing lacking in the Hartree-truncation plays a significant role in the lattice solution, leading to considerable differences in the resulting scalar power spectra. Our results indicate that a beyond-Hartree computation of 2PI-collision terms is necessary for accurate modelling of the particle production at a quantum level.
