arXiv subjects

Lingfei Wang

Publications and source records attributed to Lingfei Wang.

57 records · Page 4Linked to original sources

arXiv2013

Creating perturbations from a decaying field during inflation

Typically the fluctuations generated from a decaying field during inflation do not contribute to the large scale structures. In this paper we provide an example where it is possible for a field which slowly rolls and then decays during inflation to create all the matter perturbations with a slightly red-tilted spectral index, with no isocurvature perturbations, and with a possibility of a departure from Gaussian fluctuations.

astro-ph.CO↗

arXiv2012

Separable and non-separable multi-field inflation and large non-Gaussianity

In this paper we provide a general framework based on $δN$ formalism to estimate the cosmological observables pertaining to the cosmic microwave background radiation for non-separable potentials, and for generic \emph{end of inflation} boundary conditions. We provide analytical and numerical solutions to the relevant observables by decomposing the cosmological perturbations along the curvature and the isocurvature directions, \emph{instead of adiabatic and entropy directions}. We then study under what conditions large bi-spectrum and tri-spectrum can be generated through phase transition which ends inflation. In an illustrative example, we show that large $f_{NL}\sim {\cal O}(80)$ and $τ_{NL}\sim {\cal O}(20000)$ can be obtained for the case of separable and non-separable inflationary potentials.

astro-ph.CO↗

arXiv2011

Preheating and locked inflation: an analytic approach towards parametric resonance

We take an analytic approach towards the framework of parametric resonance and apply it on preheating and locked inflation. A two-scalar toy model is analytically solved for the λϕ^2χ^2 coupling for the homogenous modes. The effects of dynamic universe background and backreaction are taken into account. We show the average effect of parametric resonance to be that χ's amplitude doubles for each cycle of ϕ. Our framework partly solves the preheating scenario, showing two distinct stages of preheating and making the parameters of preheating analytically calculable. It is demonstrated for slowroll inflation models, preheating is terminated, if by backreaction, typically in the 5th e-fold. Under our framework, a possible inhomogeneity amplification effect is also found during preheating, which both may pose strong constraints on some inflationary models and may amplify tiny existing inhomogeneities to the desired scale. For demonstration, we show it rules out the backreaction end of preheating of the quadratic slowroll inflation model with mass m\sim10^{-6}. For locked inflation, parametric resonance is found to be inhibited if ϕ has more than one real component.

hep-th↗