Non-Gaussian Spikes from Chaotic Billiards in Inflation Preheating
J. Richard Bond, Andrei V. Frolov, Zhiqi Huang and Lev Kofman
Lattice calculation of non-Gaussianity from preheating
Alex Chambers and Arttu Rajantie
Non-Gaussian Spikes from Chaotic Billiards in Inflation Preheating
J. Richard Bond, Andrei V. Frolov, Zhiqi Huang and Lev Kofman
arXiv:0903.3407
A new class of non-Gaussian curvature fluctuations \zeta_{pr} (\bx) \equiv \delta N(\chi_i) arises from the post-inflation preheating behaviour of a non-inflaton field \chi_i. Its billiard-like chaotic dynamics imprints regular log-spaced narrow spikes in the number of preheating e-folds N(\chi_i). We perform highly accurate lattice simulations of SUSY-inspired quartic inflaton and coupling potentials in a separate-universe approximation to compute N(\chi_i) as a function of the (nearly homogeneous) initial condition \chi_i. The super-horizon modes of \chi_i(\bx) result in positive spiky excursions in \zeta_{pr} and hence negative gravitational potential fluctuations added to the usual sign-independent inflaton-induced perturbations, observably manifested in large cosmic structures and as (polarized) temperature CMB cold spots.
Lattice calculation of non-Gaussianity from preheating
Alex Chambers and Arttu Rajantie
arXiv:0710.4133
If light scalar fields are present at the end of inflation, their non-equilibrium dynamics such as parametric resonance or a phase transition can produce non-Gaussian density perturbations. We show how these perturbations can be calculated using non-linear lattice field theory simulations and the separate universe approximation. In the massless preheating model, we find that some parameter values are excluded while others lead to acceptable but observable levels of non-Gaussianity. This shows that preheating can be an important factor in assessing the viability of inflationary models.
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