Related papers: Inflation without inflatons
We revisit alternative mechanisms of gravitational wave production during inflation and argue that they generically emit a non-negligible amount of scalar fluctuations. We find the scalar power is larger than the tensor power by a factor of…
We investigate warm intermediate scenario of the cosmological inflation in $F(T)$ gravity in the limit of high dissipation. The inflationary expansion is driven by the scalar inflaton while the gravitational dynamics follow from the $F(T)$…
We investigate the inflation and reheating phenomenology in scalar-Einstein-Gauss-Bonnet theory of gravity where a scalar field non-minimally couples with the Gauss-Bonnet (GB) curvature term. Regarding the inflationary phenomenology, we…
A new modified string-inspired modular invariant supergravity model is proposed and is applied to realize the slow roll inflation in Einstein frame. Because inflation deals with Planck scale physics, the dilaton can be a strong candidate…
In most current models of inflation based on a weakly self-coupled scalar matter field minimally coupled to gravity, the period of inflation lasts so long that, at the beginning of the inflationary period, the physical wavelengths of…
In the first stages of inflationary reheating, the temperature of the radiation produced by inflaton decays is typically higher than the commonly defined reheating temperature $T_{RH} \sim (\Gamma_\phi M_P)^{1/2}$ where $\Gamma_\phi$ is the…
In the framework of Born-Infeld inspired gravity theories, which deviates from General Relativity (GR) in the high curvature regime, we discuss the viability of Cosmic Inflation without scalar fields. For energy densities higher than the…
We show that it is possible to realize an inflationary scenario even without conversion of the false vacuum energy to radiation. Such cosmological models have a deflationary stage in which $Ha^2$ is decreasing and radiation produced by…
Cosmological production of scalar, non-minimally coupled dark matter depends on the specifics of the inflationary model under consideration. We analyze both Starobinsky inflation and a quadratic potential, solve the full background…
This paper focuses on the Starobinsky model of inflation. We derive solutions for various cosmological observables, such as the scalar spectral index $n_s$, the tensor-to-scalar ratio $r$ and their runnings, as well as the number of…
A particularly attractive feature of inflation is that quantum fluctuations in the inflaton field may have seeded inhomogeneities in the cosmic microwave background (CMB) and the formation of large-scale structure. In this paper, we…
We study a generality of an inflationary scenario by integrating the Einstein equations numerically in a plane-symmetric spacetime. We consider the inhomogeneous spacetimes due to (i) localized gravitational waves with a positive…
We propose an idea to build a bridge between reheating and late-time observations in quintessential inflation by backtracking the evolution of the inflaton field from the present time to the end of reheating. This idea is implemented when…
We propose a topological inflation model in the framework of supergravity with $R$ invariance. This topological inflation model is not only free from the initial value problem of the inflaton field but also gives low reheating temperature…
One of the fundamental problems of modern cosmology is to explain the origin of all the matter and radiation in the Universe today. The inflationary model predicts that the oscillations of the scalar field at the end of inflation will…
We consider an inflationary universe model in which the phase of accelerated expansion was preceded by a non-singular bounce and a period of contraction which involves a phase of deceleration. We follow fluctuations which exit the Hubble…
We employ a viable $f(R)$ gravity model capable of giving an inflationary phase in order to study the subsequent reheating phase due to particle creation at the expense of energy in the scalaron field. Since quantum mechanics is expected to…
The energy and time scales during the inflationary stage of the universe calls for an out of equilibrium quantum field treatment. Moreover, the high energy densities involved make necessary the use of non-perturbative approaches as large N…
We started the evolution of a flat universe from a nonsingular state called prematter which is governed by an inflationary equation of state $P=(\gamma_{p}-1)\rho$ where $\gamma_{p}$ represents the initial vacuum dominance of the universe.…
We study a single fluid component in a flat like universe (FLU) governed by $f(T)$ gravity theories, where $T$ is the teleparallel torsion scalar. The FLU model, regardless the value of the spatial curvature $k$, identifies a special class…