Related papers: From New to Large Field Inflation: Comparison with…
The WMAP results on the scalar spectral index n and its running with scale, though preliminary, open a very interesting window to physics at very high energies. We address the problem of finding inflaton potentials well motivated by…
Motivated by the result of Planck+BICEP/Keck recently released, we investigate the consistency of the multi-field inflation models in terms of the spectral index $n_s$ and the tensor-to-scalar ratio $r$. In this study, we focus on…
Inflationary observables of a classically scale invariant model, in which the origin of the Planck mass and the electroweak scale including the right-handed neutrino mass is chiral symmetry breaking in a QCD-like hidden sector, are studied.…
We derive power spectra of the scalar- and tensor-type structures generated in an inflation model based on a massive non-minimally coupled scalar field with the strong coupling assumption. We make analyses in both the original-frame and the…
We present a new inflation model in which the inflationary scenario including subsequent reheating is determined in part by a U(1)_R\times Z_n symmetry. A preinflation epoch can be introduced to yield, among other things, a running spectral…
We revisit the no-scale ripple inflation model, where no-scale supergravity is modified by an additional term for the inflaton field in the Kahler potential. This term not only breaks one SU(N,1) symmetry explicitly, but also plays an…
We have realized non-minimal Higgs inflation and standard hybrid inflation in the supersymmetric flipped $SU(5)$ model with $U(1)_R$ symmetry using the no-scale form of the K\"{a}hler potential. In non-minimal Higgs inflation the waterfall…
We study the possibility that inflation is driven by a massive vector field with SO(3) global symmetry nonminimally coupled to gravity. From an E^3-invariant Robertson-Walker metric we propose an Ansatz for the vector field, allowing us to…
We study a modification of the Higgs inflation scenario where we introduce an extra scalar $\phi$, with mass $m$, coupled to the Ricci scalar as $g\phi^2 R$, and mixed with the Higgs field $h$ via the Lagrangian term $\mu \phi h^2$. Both…
In this paper we will analyse the constraints on a sub-Planckian excursion of a single inflaton field, which would yield a large tensor to scalar ratio, while explaining the temperature anisotropy of the cosmic microwave background (CMB)…
A model is developed in which the inflaton potential experiences a sudden small change in its second derivative (the effective mass of the inflaton). An exact treatment demonstrates that the resulting density perturbation has a quasi-flat…
We point out that the prediction of the minimal chaotic inflation model is altered if a scalar field takes a large field value close to the Planck scale during inflation due to a negative Hubble induced mass. In particular, we show that the…
We study inflation and preheating in F(R) supergravity characterized by two mass scales of a scalar degree of freedom (scalaron): M (associated with the inflationary era) and m (associated with the preheating era). The allowed values of the…
We consider a massless scalar field, conformally coupled to the Ricci scalar curvature, in the pre-inflation era of a closed FLRW Universe. The scalar field potential can be of the form of the Coleman-Weinberg one-loop potential, which is…
We study viable small-field Coleman-Weinberg (CW) inflation models with the help of non-minimal coupling to gravity. The simplest small-field CW inflation model (with a low-scale potential minimum) is incompatible with the cosmological…
A new inflationary scenario whose exponential potential $V(\Phi)$ has a quadratic dependence on the field $\Phi$ in addition to the standard linear term is confronted with the tree-year observations of the Wilkinson-Microwave Anisotropy…
We construct a phenomenological model of electroweak-scale inflation that is in accordance with recent cosmic microwave background observations by WMAP, while setting the stage for a zero-temperature electroweak transition as assumed in…
A scalar potential obtained from the $D$-term in the Supergravity models, which dominates over $F$ term and is mainly responsible for the inflationary phase in the early universe, is studied. The potential with canonical kinetic terms for…
A model of inflation is presented where the inflaton field is a complex scalar field coupled to a U(1) gauge field. Due to the axial symmetry of the potential, the inflation is driven by the radial direction while the angular field is…
We present a minimal axion inflation model which can generate a large tensor-to-scalar ratio while remaining sub-Planckian. The modulus of a complex scalar field $\Phi$ with a $\lambda |\Phi|^4$ potential couples directly to the gauge field…