Reheating in the Presence of Inhomogeneous Noise
نویسندگان
چکیده
Explosive particle production due to parametric resonance is a crucial feature of reheating in inflationary cosmology. Coherent oscillations of the inflaton field lead to a periodically varying mass in the evolution equation of matter and gravitational fluctuations and often induce a parametric resonance instability. In a previous paper (hep-ph/9709273) it was shown that homogeneous (i.e. space-independent) noise leads to an increase of the generalized Floquet exponent for all modes, at least if the noise is temporally uncorrelated. Here we extend the results to the physically more realistic case of spatially inhomogeneous noise. We demonstrate modulo some mathematical fine points which are addressed in a companion paper that the Floquet exponent is a non-decreasing function of the amplitude of the noise. We provide numerical evidence for an even stronger statement, namely that in the presence of inhomogeneous noise, the Floquet exponent of each mode is larger than the maximal Floquet exponent of the system in the absence of noise.
منابع مشابه
Inhomogeneous reheating scenario with low scale inflation and/or MSSM flat directions
We discuss the constraints on the inhomogeneous reheating scenario. In particular, we discuss the prospects for low scale inflation with a Hubble constant of the order of the gravitino mass, and the possibility that an MSSM flat direction is responsible for the density fluctuations. Thermal effects are generically fatal for the scenario, and can only be avoided for small enough mass and couplin...
متن کاملOn the effect of low-quality node observation on learning over incremental adaptive networks
In this paper, we study the impact of low-quality node on the performance of incremental least mean square (ILMS) adaptive networks. Adaptive networks involve many nodes with adaptation and learning capabilities. Low-quality mode in the performance of a node in a practical sensor network is modeled by the observation of pure noise (its observation noise) that leads to an unreliable measurement....
متن کاملChaotic Reheating
We discuss the structure of parametric resonance which occurs in the process of reheating after inflation with two interacting scalar fields. It is found that, for the case of a not too large coupling constant, a quasi-homogeneous part of the second, initially subdominant scalar field may not be neglected due to its stochastic growth during inflation. This fact has strong consequences for the r...
متن کاملReheating in the Presence of Noise
Explosive particle production due to parametric resonance is a crucial feature of reheating in in ationary cosmology. Coherent oscillations of the in aton eld act as a periodically varying mass in the evolution equation for matter elds which couple to the in aton. This in turn results in the parametric resonance instability. Thermal and quantum noise will lead to a nonperiodic perturbation in t...
متن کاملOn the Amount of Gravitational Waves from Inflation
The curvaton and the inhomogeneous reheating scenarios for the generation of the cosmological curvature perturbation on large scales represent an alternative to the standard slow-roll scenario where the observed density perturbations are due to fluctuations of the inflaton field itself. The basic assumption of the curvaton and inhomogeneous reheating mechanisms is that the initial curvature per...
متن کامل