Related papers: Massive Graviton on a Spatial Condensate
When four scalar fields with global Lorentz symmetry are coupled to gravity and take a vacuum expectation value breaking diffeomorphism invariance spontaneously, the graviton becomes massive. This model is supersymmetrized by considering…
Cosmological inflation is discussed in the framework of $F(R,{\cal G})$ gravity where $F$ is a generic function of the curvature scalar $R$ and the Gauss-Bonnet topological invariant $\cal G$. The main feature that emerges in this analysis…
We consider the production of gravitons in an inflationary cosmology by approximating each epoch of change in the equation of state as sudden, from which a simple analytic graviton mode function has been derived. We use this mode function…
We characterize graviton non-Gaussianities in models of inflation where de Sitter boosts are spontaneously broken. We discuss which of the symmetry breaking patterns studied in Nicolis et al., 2015 can sustain a period of quasi de Sitter…
We study the scalar and tensor perturbations generated by the fragmentation of the inflaton condensate into oscillons or transients after inflation, using nonlinear classical lattice simulations. Without including the backreaction of metric…
We discuss the production of gravity waves from the fragmentation of a supersymmetric condensate in the early universe. Supersymmetry predicts the existence of flat directions in the potential. At the end of inflation, the scalar fields…
We point out that the inflaton spontaneously decays into any gauge bosons and gauginos via the super-Weyl, Kahler and sigma-model anomalies in supergravity, once the inflaton acquires a non-vanishing vacuum expectation value. In particular,…
It has been claimed that the super Hubble modes of the graviton generated during inflation can make loop corrections diverge. Even if we introduce an infrared (IR) cutoff at a comoving scale as an ad hoc but a practical way for the…
The $R^2$ inflation which is an extension of general relativity (GR) by quadratic scalar curvature introduces a quasi-de Sitter expansion of the early Universe governed by Ricci scalar being an eigenmode of d'Alembertian operator. In this…
We show that the hybrid inflation is naturally realized in the framework of a supersymmetric axion model, which is consistent with the WMAP observation if the Peccei-Quinn symmetry breaking scale is around 10^{15}GeV. By solving the post…
A variant of hybrid inflation which is applicable in a wide class of supersymmetric grand unified models and reproduces the observed temperature perturbations of cosmic background radiation with natural values of the parameters is…
We present an introduction to cosmic inflation in the framework of Palatini gravity, which provides an intriguing alternative to the conventional metric formulation of gravity. In the latter, only the metric specifies the spacetime…
Weyl (scale) invariant theories of scalars and gravity can generate all mass scales spontaneously. In this paper we study a particularly simple version -- scale invariant $R^2$ gravity -- and show that, during an inflationary period, it…
We construct a hybrid-inflation model where the inflaton potential is generated radiatively, as gauge symmetries guarantee it to be accidentally flat at tree level. The model can be regarded as a small-field version of Natural Inflation,…
Within supersymmetry we provide an example where the inflaton sector is derived from a gauge invariant polynomial of SU(N) or SO(N) gauge theory. Inflation in our model is driven by multi-flat directions, which assist accelerated expansion.…
It was recently shown that gravitons with a very small mass should have formed a Bose-Einstein condensate in the very early Universe, whose density and quantum potential can account for the dark matter and dark energy in the Universe…
In this paper, we study the cosmological inflation phenomenon in symmergent gravity theory. Symmergent gravity is a novel framework which merges gravity and the standard model (SM) so that the gravity emerges from the matter loops and…
We study the evolution of Gravitational Waves (GWs) during and after inflation as well as the resulting observational consequences in a Lorentz-violating massive gravity theory with one scalar (inflaton) and two tensor degrees of freedom.…
We consider the torsional completion of gravity with spinor and scalar fields: we show how in this environment conditions of extreme symmetry or specific approximations imply the scalar field to be constant, so that slow-roll takes place…
The quantum gravitational back-reaction on inflation is based on the self-gravitation of infrared gravitons which are ripped out of the vacuum during inflation. The only quantum part of this process is the creation of gravitons; after they…