Related papers: Pre-inflation models and WMAP data
In low-energy effective string theory, $\alpha'$ corrections involve the coupling of the dilaton field to Gauss-Bonnet term. We assume that the dilaton potential is fine tuned so that the dilaton field may oscillate rapidly for a while…
The solution to large-scale power deficit in the cosmic microwave background fluctuations may be relevant with the physics in the preinflationry period, and significantly depends on whether the initial conditions are set as Bunch-Davies…
There is an apparent power deficit relative to the $\Lambda$CDM prediction of the CMB spectrum at large scales, which, though not yet statistically significant, persists from WMAP to Planck data. Proposals that invoke some form of initial…
We consider a quantum deformation of the wave equation on a cosmological background as a toy-model for possible trans-Planckian effects. We compute the power spectrum of scalar and tensor fluctuations for power-law inflation, and find a…
An epoch of accelerated expansion, or inflation, in the early universe solves several cosmological problems. While there are many models of inflation only recently has it become possible to discriminate between some of the models using…
The characteristics of the cosmic microwave background provide circumstantial evidence that the hot radiation-dominated epoch in the early universe was preceded by a period of inflationary expansion. Here, we show how a measurement of the…
If an adiabatic density perturbation is responsible for large scale structure and the cmb anisotropy, its spectral index $n$ will be measured in the forseeable future with an accuracy $\Delta n\sim .01$. This is precisely the kind of…
We explore the noncommutative effect on single field inflation and compare with WMAP five-year data. First, we calculate the noncommutative effect from the potential and dynamical terms, and construct the general form of modified power…
Inter alia, the high precision WMAP data on Cosmic Microwave Background Radiation marginally indicate that the universe has positively curved (and hence spherical) spatial sections. In this paper, we take this data seriously and consider…
Inflation in cosmology is a specific stage preceding the Big Bang, aimed at solving both old background problems and new perturbation issues. Single-field inflation is a candidate to illustrate the picture of the initial universe, and…
In this paper, we investigate scalar-induced gravitational waves (GWs) generated in the post-inflationary universe to infer new limits on warm inflation. We specifically examine the evolution of primordial GWs by scalar perturbations…
Fluctuations in the intensity and polarization of the cosmic microwave background (CMB) and the large-scale distribution of matter in the universe each contain clues about the nature of the earliest moments of time. The next generation of…
We investigate the scalar mode of perturbation of super inflation in the version of loop quantum cosmology in which the gauge invariant holonomy corrections are considered. Given a background solution, we calculate the power spectrum of the…
The recent detection of the primordial gravitational waves from the BICEP2 observation seems to be in tension with the upper bound on the amplitude of tensor perturbations from the PLANCK data. We consider a phenomenological model of…
Preheating after inflation involves large, time-dependent field inhomogeneities, which act as a classical source of gravitational radiation. The resulting spectrum might be probed by direct detection experiments if inflation occurs at a low…
The scalar induced gravitational waves (SIGWs) is a useful tool to probe the physics in the early universe. To study inflationary models with this tool, we need to know how the waveform of SIGWs is related to the shape of the scalar power…
Solid inflation is an effective field theory of inflation in which isotropy and homogeneity are accomplished via a specific combination of anisotropic sources (three scalar fields that individually break isotropy). This results in specific…
The angular power spectrum of the cosmic microwave background temperature anisotropy observed by WMAP has an anomalous dip at l~20 and bump at l~40. One explanation for this structure is the presence of features in the primordial curvature…
We analyse the implications of the Wilkinson Microwave Anisotropy Probe (WMAP) results for a braneworld tachyonic model of inflation. We find that WMAP bounds on $n_s$ allow us to constrain significantly the parameter space of the model; in…
Inflationary models predicting a scale-dependent large amplification of the density perturbations have recently attracted a lot of attention because the amplified perturbations can seed a sizable amount of primordial black holes (PBHs) and…