Non-Gaussianity from Particle Production during Inflation

Figure 6

The power spectrum of inflaton modes induced by rescattering (normalized to the usual vacuum fluctuations) as a function of ln(𝑘/𝑘_⋆), plotted for three representative time steps in the late-time evolution. This figure illustrates the final stages of IR cascading; we see the peak of the bump-like feature slide to 𝑘∼𝑒⁻³𝑘_⋆, at which point the associated mode functions 𝛿𝜙_𝑘 have crossed the horizon and become frozen. At later times in the evolution the peak of the feature and also the IR tail (~𝑘³) remain fixed. Modes associated with the UV end of the spectrum are still inside the horizon and continue to evolve as 𝛿𝜙_𝑘∼𝑎⁻¹, which explains the damping of the 𝑘>𝑒⁻²𝑘_⋆ part of the spectrum. For each time step we plot the analytical result (the solid line) and the data points obtained using lattice field theory simulations (diamonds).