Search Publications
Non-Gaussianities in DBI inflation with angular motion
Kidani, Taichi; Koyama, Kazuya
We study DBI spinflation models with angular potentials that are derived in string theory. We analyze the background dynamics with different parameter sets and study the impact of changing each parameter on inflationary dynamics. It is known that the conversion of the entropy perturbation into the curvature perturbation gives multifield Dirac-Born…
Updated constraints on large field hybrid inflation
Clesse, Sébastien; Rekier, Jérémy
We revisit the status of hybrid inflation in the light of Planck and recent BICEP2 results, taking care of possible transient violations of the slow-roll conditions as the field passes from the large field to the vacuum dominated phase. The usual regime where observable scales exit the Hubble radius in the vacuum dominated phase predicts a blue sc…
Planck constraints on neutrino isocurvature density perturbations
Di Valentino, Eleonora; Melchiorri, Alessandro
The recent cosmic microwave background data from the Planck satellite experiment, when combined with Hubble Space Telescope determinations of the Hubble constant, are compatible with a larger, nonstandard number of relativistic degrees of freedom at recombination, parametrized by the neutrino effective number Neff . In the curvaton scen…
Observational effects of the early episodically dominating dark energy
Park, Chan-Gyung; Lee, Jae-heon; Hwang, Jai-chan +1 more
We investigate the observational consequences of the early episodically dominating dark energy on the evolution of cosmological structures. For this aim, we introduce the minimally coupled scalar-field dark energy model with the Albrecht-Skordis potential, which allows a sudden ephemeral domination of a dark energy component during the radiation o…
Is Planck data consistent with primordial deuterium measurements?
Melchiorri, Alessandro; Salvati, Laura; Said, Najla
The recent measurements of the cosmic microwave background anisotropies provided by the Planck satellite experiment have significantly improved the constraints on several cosmological parameters. In this brief paper we point out a small but interesting tension present between recent values of the primordial deuterium measured from quasar absorptio…
Test for the zero mean hypothesis in cosmology
Ichiki, Kiyotomo
One working hypothesis on which analyses of cosmological data are based is the zero ensemble mean hypothesis, which is related to the statistical homogeneity of cosmological perturbations. This hypothesis, however, should be tested by observational data in the current era of precision cosmology. Herein, we test the hypothesis by analyzing recent, …
Higher order nonlinear parameters with Planck constraints
Takahashi, Tomo; Gong, Jinn-Ouk
We investigate how higher-order nonlinear parameters affect lower-order ones through loop effects. We calculate the loop corrections up to two loops and explicitly show that the tree contribution is stable against loop terms in most cases. We argue that, nevertheless, observational constraints on nonlinear parameters such as fNL and τ
New constraints on coupled dark energy from the Planck satellite experiment
Mena, Olga; Salvatelli, Valentina; Marchini, Andrea +1 more
We present new constraints on coupled dark energy from the recent measurements of the cosmic microwave background anisotropies from the Planck satellite mission. We found that a coupled dark energy model is fully compatible with the Planck measurements, deriving a weak bound on the dark matter-dark energy coupling parameter ξ=-0.49-0.31…
Obtaining the CMB anomalies with a bounce from the contracting phase to inflation
Liu, Zhi-Guo; Guo, Zong-Kuan; Piao, Yun-Song
Recent Planck data show the anomalies of cosmic microwave background (CMB) fluctuations on large angular scales, which confirms the early observations by WMAP. We continue studying an inflationary model, in which before the slow-roll inflation the universe is in a contracting phase, and fit the model with the Planck data. We show that this model m…
Constraints on millicharged particles from Planck data
Dolgov, A. D.; Tkachev, I. I.; Rubtsov, G. I. +1 more
We revisit cosmic microwave background constraints on the abundance of millicharged particles based on the Planck data. The stringent limit Ωmcph2<0.001 (95% CL) may be set using the cosmic microwave background data alone if millicharged particles participate in the acoustic oscillations of baryon-photon plasma at the reco…