Related papers: A universal scaling law for gravitational waves in…
We derive the complete spectrum of gravitational waves induced by primordial scalar perturbations ranging over all observable wavelengths. This scalar-induced contribution can be computed directly from the observed scalar perturbations and…
Scalar induced gravitational waves contribute to the cosmological gravitational wave background. They can be related to the primordial density power spectrum produced towards the end of inflation and therefore are a convenient new tool to…
We study the inflationary gravitational wave background induced by Abelian gauge fields generated by non-minimal kinetic and axial couplings to the inflaton. We show that, up to slow-roll corrections, for coupling functions that share the…
The primordial spectrum of fluctuations may present a large peak as a result of enhancing features during inflation. This may include, but is not limited to, bumps in the inflaton's potential, phases of ultra-slow-roll or turns in…
The effect of the initial conditions in inflation on scalar and tensor perturbations is investigated. Formulae for the power spectra of gravitational waves and curvature perturbations for any initial conditions in inflation are derived, and…
The spectrum of the gravitational wave background originating from quantum fluctuations during inflation is calculated numerically for various inflation models over a wide range of frequencies. We take into account four ingredients : the…
We study cosmological gravitational waves generated during inflation under the influence of a decaying cosmological "constant", in the Transverse-Traceless (TT) gauge. In our approach we consider a non-perturbative contribution of the…
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…
Using a large N sigma model approximation we explicitly calculate the power spectrum of gravitational waves arising from a global phase transition in the early universe and we confirm that it is scale invariant, implying an observation of…
We show that the anisotropies in the spectrum of gravitational waves induced by scalar modes after the end of inflation in canonical, single-field models are completely determined by the tilt of the scalar and tensor power spectra. The…
We present a general and unified formulation which can handle the classical evolution and quantum generation processes of the cosmological gravitational wave in a broad class of generalized gravity theories. Applications are made in several…
The production of a stochastic background of gravitational waves is a fundamental prediction of any cosmological inflationary model. The features of such a signal encode unique information about the physics of the Early Universe and beyond,…
We study the general infrared behavior of the power spectrum of a stochastic gravitational wave background produced by stress tensor in the form bilinear in certain dynamical degrees of freedom. We find $\Omega_{\text{GW}}\propto k^3$ for a…
We discuss a cosmological scenario with a stochastic background of gravitational waves sourced by the tensor perturbation due to a hybrid inflationary model with cubic potential. The tensor-to-scalar ratio for the present hybrid…
If primordial scalar or tensor perturbations are enhanced on short scales, it may lead to the production of observable gravitational wave signals. These waves may be sourced by scalar-scalar, scalar-tensor or tensor-tensor interactions.…
The curvaton scenario for the generation of the cosmological curvature perturbation on large scales represents an alternative to the standard slow-roll scenario of inflation in which the observed density perturbations are due to…
The inflationary 1-loop tensor power spectrum from an excited spectator scalar field is calculated. Recent studies on primordial black holes suggest that the inflationary curvature perturbation may be huge on small scales. An enhanced…
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…
It is widely accepted that the primordial universe experienced a brief period of accelerated expansion called inflation. This scenario provides a plausible solution to the horizon and flatness problems. However, the particle physics…
The detection of Primordial Gravitational Waves (PGWs) is one of the most important goals of modern cosmology since PGWs can both provide substantial evidence for primordial inflation and shed light on its physical nature. Small scale…