相关论文: Accurately determining inflationary perturbations
We reconsider the problems of cosmological inflation in effective supergravity theories. A singlet field in a hidden sector is demonstrated to yield an acceptable inflationary potential, without fine tuning. In the simplest such model, the…
Modified gravity theories are supposed to incorporate low-energy quantum-gravity effects and, at the same time, they could shed light into the dark matter and dark energy problems. Here we study a particular modification of general…
We recently derived exact solutions for the scalar, vector and tensor mode functions of a single, minimally coupled scalar plus gravity in an arbitrary homogeneous and isotropic background. These solutions are applied to obtain improved…
We investigate the one loop effective potential of inflation in a standard model of chaotic inflation. The leading one loop corrections to the effective inflaton potential are evaluated in the quasi de Sitter background, and we estimate the…
How well can we constrain the initial quantum state of metric perturbations sourced during inflation? We exhibit an interesting new class of quantum states that entangle the scalar metric perturbations {\zeta} with other fields such as…
The presence of multiple fields during inflation might seed a detectable amount of non-Gaussianity in the curvature perturbations, which in turn becomes observable in present data sets like the cosmic microwave background (CMB) or the large…
We derive constraints on a simple quintessential inflation model, based on a spontaneously broken Phi^4 theory, imposed by the Wilkinson Microwave Anisotropy Probe three-year data (WMAP3) and by galaxy clustering results from the Sloan…
We investigate perturbations in power-law monomial potentials within inflationary models driven by a single scalar field. By introducing a second term to the original potential, we study how this perturbation influences the slow-roll…
We present a simple, yet accurate approximation for calculating the cosmic microwave background anisotropy power spectrum in adiabatic models. It consists of solving for the evolution of a two-fluid model until the epoch of recombination…
Isentropic and isocurvature axion inflationary perturbations are studied in detail. If isocurvature perturbations are present, COBE requires the inflationary Hubble constant to be rather small, $H_{I} \stackrel{<}{\sim} 10^{12}$GeV,…
We revisit perturbative unitarity in scalar field inflation with a nonminimal coupling, with Higgs inflation serving as the most prominent example. Although such models are phenomenologically successful, it is critical to examine whether or…
We demonstrate that the approximation for the number of inflationary e-folds commonly used in the literature can lead to highly inaccurate predictions for the amplitude of primordial gravitational waves. We show that such an approximation…
Inflation generates gravitational waves, which may be observable in the low multipoles of the cosmic microwave background (cmb) anisotropy but only if the inflaton field variation is at least of order the Planck scale. Such a large…
A procedure is developed for the recovery of the inflationary potential over the interval that affects astrophysical scales ($\approx 1\Mpc - 10^4\Mpc$). The amplitudes of the scalar and tensor metric perturbations and their power-spectrum…
We set up a formalism that can be used to calculate the power spectrum of the curvature perturbations produced during inflation up to arbitrary order in the slow-roll expansion, and explicitly calculate the power spectrum and spectral index…
Recent fits of cosmological parameters by the Wilkinson Microwave Anisotropy Probe (WMAP) measurement favor a primordial scalar spectrum with varying index. This result, if stands, could severely constrain inflation model buildings. Most…
We analyze cosmological perturbations to the linear order in the context of inflation with an arbitrary number of scalar fields. The fields take values on a non-trivial manifold with a positive-definite metric and are non-minimally coupled…
The perturbative approach to stochastic inflation is used to determine the spectrum of density fluctuations and gravitational waves due to the coarse grained field. The amplitude of the curvature fluctuation spectrum, the spectral index and…
Detection of the tensor perturbations predicted in inflationary models is important for testing inflation as well as for reconstructing the inflationary potential. We show that because of cosmic variance the tensor contribution to the…
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…