Related papers: A Potential Window to the GUT
We study the possibility that particle production during inflation could source observable gravity waves on scales relevant for Cosmic Microwave Background experiments. A crucial constraint on such scenarios arises because particle…
We investigate the range of inflationary universe models driven by scalar fields possessing a general interaction potential of the form $V(\phi) = V_0 \phi^n \exp(-\lambda \phi^m)$. Power-law, de Sitter and intermediate inflationary…
Motivated by the gauge theory of gravity with local scaling symmetry proposed recently in 1712.04537 and 1506.01807, we investigate whether the scalar field therein can be responsible for the inflation. We show that the classical theory…
Inflation predicts a primordial gravitational wave spectrum that is slightly ``red,'' i.e., nearly scale-invariant with slowly increasing power at longer wavelengths. In this paper, we compute both the amplitude and spectral form of the…
We study observational bounds in a class of scalar-tensor gravity theories recently proposed. Either an upper or lower bound on a conformal factor in these theories is derived from null observation in composition dependent fifth force…
We investigate the inhomogeneous inflation, in which the space exponentially expands with inhomogeneities, and its cosmological perturbations. The inhomogeneous inflation is realized by introducing scalar fields with spacelike gradients…
The observational data on the anisotropy of the cosmic microwave background constraints the scalar spectral tilt $n_s$ and the tensor to scalar ratio $r$ which depend on the first and second derivatives of the inflaton potential. The…
Power spectra always play an important role in the theory of inflation. In particular, the ability to reproduce the galaxy matter power spectrum and the CMB temperature angular power spectrum coefficients to high accuracy is often…
We investigate the warm inflationary scenario within the context of the linear version of f (Q, T ) gravity, coupled with both the inflaton scalar field and the radiation field, under the conditions of the strong dissipation regime. First,…
I discuss a mechanism that renders the spectral index of the primordial spectrum and the inflationary stage independent of each other. If a scalar field acquires an appropriate time-dependent mass, it is possible to generate an adiabatic,…
We study cosmological tensor perturbations generated during de Sitter inflation in the conformal gravity with mass parameter $m^2=2H^2$. It turns out that tensor power spectrum is scale-invariant.
We study in detail the power spectra of scalar and tensor perturbations generated during inflation in loop quantum cosmology (LQC). After clarifying in a novel quantitative way how inverse-volume corrections arise in inhomogeneous settings,…
Inflation may provide unique insight into the physics at the highest available energy scales that cannot be replicated in any realistic terrestrial experiment. Features in the primordial power spectrum are generically predicted in a wide…
A viable model for inflation driven by a torsion function in a Friedmann background is presented. The scalar spectral index in the interval $0.92\lesssim n_{s}\lesssim 0.97$ is obtained in order to satisfy the initial conditions for…
Unimodular gravity is an alternative theory of gravity to general relativity. The gravitational field equations are given by the trace-free version of Einstein's field equations. Due to the structure of the theory, unimodular gravity admits…
Purely geometrical arguments show that there exist classes of homospectral inflationary cosmologies, i.e. different expansion histories producing the same spectrum of comoving curvature perturbations. We develop a general algorithm to…
We consider the reconstruction technique in theories with a single or multiple (phantom and/or canonical) scalar fields. With the help of several examples, it is demonstrated explicitly that the universe expansion history, unifying…
We study the scalar induced gravitational wave (GW) background in inflation with gravitationally enhanced friction (GEF). The GEF mechanism, which is realized by assuming a nonminimal derivative coupling between the inflaton field and…
We study a new class of inflation model parametrized by the Hubble radius, such that $aH\propto \exp(-k\phi^n)$. These potentials are plateau-like, and reduce to the power-law potentials in the simplest case $n=2$. We investigate the range…
In this paper we present a model for accelerated expansion of the universe, both during inflation and the present stage of the expansion, from four dimensional $\mathcal{N}=1$ supergravity. We evaluate the tensor-to-scalar ratio ($r\approx…