Search Publications
Accidental inflation from Kähler uplifting
Ben-Dayan, Ido; Jing, Shenglin; Westphal, Alexander +1 more
We analyze the possibility of realizing inflation with a subsequent dS vacuum in the Käahler uplifting scenario. The inclusion of several quantum corrections to the 4d effective action evades previous no-go theorems and allows for construction of simple and successful models of string inflation. The predictions of several benchmark models are in a…
Scale-dependent hemispherical asymmetry from general initial state during inflation
Gong, Jinn-Ouk; Firouzjahi, Hassan; Namjoo, Mohammad Hossein
We consider a general initial state for inflation as the mechanism for generating scale-dependent hemispherical asymmetry. An observable scale-dependent non-Gaussianity is generated that leads to observable hemispherical asymmetry from the super-horizon long mode modulation. We show that the amplitude of dipole asymmetry falls off exponentially on…
SCoPE: an efficient method of Cosmological Parameter Estimation
Das, Santanu; Souradeep, Tarun
Markov Chain Monte Carlo (MCMC) sampler is widely used for cosmological parameter estimation from CMB and other data. However, due to the intrinsic serial nature of the MCMC sampler, convergence is often very slow. Here we present a fast and independently written Monte Carlo method for cosmological parameter estimation named as Slick Cosmological …
Probing neutrinos from Planck and forthcoming galaxy redshift surveys
Kadota, Kenji; Takeuchi, Yoshitaka
We investigate how much the constraints on the neutrino properties can be improved by combining the CMB, the photometric and spectroscopic galaxy redshift surveys which include the CMB lensing, galaxy lensing tomography, galaxy clustering and redshift space distortion observables. We pay a particular attention to the constraint on the neutrino mas…
How does pressure gravitate? Cosmological constant problem confronts observational cosmology
Afshordi, Niayesh; Scott, Douglas; Narimani, Ali
An important and long-standing puzzle in the history of modern physics is the gross inconsistency between theoretical expectations and cosmological observations of the vacuum energy density, by at least 60 orders of magnitude, otherwise known as the cosmological constant problem. A characteristic feature of vacuum energy is that it has a pressure …
Reconciling BICEP2 and Planck results with right-handed Dirac neutrinos in the fundamental representation of grand unified E6
Anchordoqui, Luis A.; Goldberg, Haim; Vlcek, Brian J. +1 more
The tensor-to-scalar ratio (r = 0.20+0.07-0.05) inferred from the excess B-mode power observed by the Background Imaging of Cosmic Extragalactic Polarization (BICEP2) experiment is almost twice as large as the 95% CL upper limits derived from temperature measurements of the WMAP (r < 0.13) and Planck (r < 0.11) space mi…
Observational tests of backreaction with recent data
Maino, Davide; Chiesa, Matteo; Majerotto, Elisabetta
We explore the backreaction model based on the template metric proposed in Larena et al. [1] constraining the matter density parameter ΩmD0 and the Dark Energy parameter w with recent data. We provide constraints based on Supernovae Ia from the SNLS and the Union2.1 catalogs, confirming that the backreacted Univers…
Clustering GCG: a viable option for unified dark matter-dark energy?
Kumar, Sumit; Sen, Anjan A.
We study the clustering Generalized Chaplygin Gas (GCG) as a possible candidate for dark matter-dark energy unification. The vanishing speed of sound 0cs2 = ) for the GCG fluid can be obtained by incorporating higher derivative operator in the original K-essence Lagrangian. The evolution of the density fluctuations in the GCG…
Constraints on dark energy from new observations including Pan-STARRS
Zheng, Wei; Li, Mingzhe; Xia, Jun-Qing +3 more
In this paper, we set the new limits on the equation of state parameter (EoS) of dark energy with the observations of cosmic microwave background radiation (CMB) from Planck satellite, the type Ia supernovae from Pan-STARRS and the baryon acoustic oscillation (BAO). We consider two parametrization forms of EoS: a constant w and time evolving w(a)=…
Composite inflation confronts BICEP2 and PLANCK
Channuie, Phongpichit; Karwan, Khamphee
We examine observational constraints on single-field inflation in which the inflaton is a composite field stemming from a four-dimensional strongly interacting field theory. We confront the predictions with the Planck and very recent BICEP2 data. In the large non-minimal coupling regions, we discover for the minimal composite inflationary model th…