Abstract
We consider a quasi-single field inflation model in which the inflaton interacts with a massive scalar field called the isocurvaton. Due to the breaking of time translational invariance by the inflaton background, these interactions induce kinetic mixing between the inflaton and isocurvaton, which is parameterized by a constant $\mu$. We derive analytic formulae for the curvature perturbation two-, three-, four-, five-, and six-point functions explicitly in terms of the external wave-vectors in the limit where $\mu$ and the mass of the isocurvaton $m$ are both much smaller than $H$. In previous work, it has been noted that when $m/H$ and $\mu/H$ are small, the non-Gaussianities predicted by quasi-single field inflation give rise to long wavelength enhancements of the power spectrum for biased objects (e.g., galactic halos). We review this calculation, and calculate the analogous enhanced contribution to the bispectrum of biased objects. We determine the scale at which these enhanced terms are larger than the Gaussian piece. We also identify the scaling of these enhanced parts to the $n$-point function of biased objects.
Highlights
The inflationary paradigm [1] proposes an era in the very early universe during which the energy density is dominated by vacuum energy
It has been noted that when m=H and μ=H are small, the non-Gaussianities predicted by quasi-single field inflation give rise to long wavelength enhancements of the power spectrum for biased objects
We identify the scaling of these enhanced parts to the n-point function of biased objects
Summary
The inflationary paradigm [1] proposes an era in the very early universe during which the energy density is dominated by vacuum energy. One complication that is not present for the microwave background radiation is that galaxies are biased objects They do not trace the mass distribution but rather arise at special points, for example where the fluctuations in the mass density exceed some threshold. It was realized in [5,6] that the power spectrum for biased objects can deviate significantly from Harrison-Zeldovich on large scales if the primordial mass density perturbations are non-Gaussian. Quantitative predictions for the power spectrum of galactic halos in quasi-single field inflation (and other models for non-Gaussian primordial fluctuations) were recently made in [8]. We identify the scaling of the n-point function of the halo overdensity in quasi-single field inflation within this threshold model.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have