Search Publications
Inflation with moderately sharp features in the speed of sound: Generalized slow roll and in-in formalism for power spectrum and bispectrum
Hu, Bin; Torrado, Jesús; Achúcarro, Ana +2 more
We continue the study of mild transient reductions in the speed of sound of the adiabatic mode during inflation, of their effect on the primordial power spectrum and bispectrum, and of their detectability in the cosmic microwave background (CMB). We focus on the regime of moderately sharp mild reductions in the speed of sound during uninterrupted …
Two-zero Majorana textures in the light of the Planck results
Meloni, Davide; Meroni, Aurora; Peinado, Eduardo
The recent results of the Planck experiment put a stringent constraint on the sum of the light neutrino masses, Σimi<0.23 eV (95% C.L.). On the other hand, two-zero Majorana mass matrix textures predict strong correlations among the atmospheric angle sin2θ23 and Σ. We use the Planck result to show that, for the …
Compatibility of Planck and BICEP2 results in light of inflation
Ringeval, Christophe; Trotta, Roberto; Martin, Jérôme +1 more
We investigate the implications for inflation of the detection of B-modes polarization in the cosmic microwave background by BICEP2. We show that the hypothesis of the primordial origin of the measurement is favored only by the first four band powers, while the others would prefer unreasonably large values of the tensor-to-scalar ratio. Using only…
Self-calibration of BICEP1 three-year data and constraints on astrophysical polarization rotation
Ade, P. A. R.; Bock, J. J.; Chiang, H. C. +33 more
Cosmic microwave background (CMB) polarimeters aspire to measure the faint B-mode signature predicted to arise from inflationary gravitational waves. They also have the potential to constrain cosmic birefringence, rotation of the polarization of the CMB arising from parity-violating physics, which would produce nonzero expectation values for the C…
Nonlocal gravity and structure in the Universe
Dodelson, Scott; Park, Sohyun
The observed acceleration of the Universe can be explained by modifying general relativity. One such attempt is the nonlocal model of Deser and Woodard. Here we fix the background cosmology using results from the Planck satellite and examine the predictions of nonlocal gravity for the evolution of structure in the Universe, confronting the model w…
Coupled dark energy with perturbed Hubble expansion rate
Yang, Weiqiang; Xu, Lixin
The coupling between dark sectors provides a possible approach to mitigate the coincidence problem of the cosmological standard model. In this paper, dark energy is treated as a fluid with a constant equation of state, whose coupling with dark matter is proportional the Hubble parameter and energy density of dark energy, that is, Q ¯ =3 ξx
Can a supervoid explain the cold spot?
Nadathur, Seshadri; Räsänen, Syksy; Hotchkiss, Shaun +1 more
The discovery of a void of size ∼200 h-1 Mpc and average density contrast of ∼-0.1 aligned with the cold spot direction has been recently reported. It has been argued that, although the first-order integrated Sachs-Wolfe (ISW) effect of such a void on the cosmic microwave background is small, the second-order Rees-Sciama (RS) contributi…
Primordial magnetic field limits from the CMB trispectrum: Scalar modes and Planck constraints
Subramanian, Kandaswamy; Seshadri, T. R.; Trivedi, Pranjal
Cosmic magnetic fields are observed to be coherent on large scales and could have a primordial origin. Non-Gaussian signals in the cosmic microwave background (CMB) are generated by primordial magnetic fields as the magnetic stresses and temperature anisotropy they induce depend quadratically on the magnetic field. We compute the CMB scalar trispe…
Steps to reconcile inflationary tensor and scalar spectra
Hu, Wayne; Miranda, Vinícius; Adshead, Peter
The recent BICEP2 B-mode polarization determination of an inflationary tensor-scalar ratio r=0.2-0.05+0.07 is in tension with simple scale-free models of inflation due to a lack of a corresponding low multipole excess in the temperature power spectrum which places a limit of r0.002<0.11 (95% C.L.) on such models. Single-field inflati…
Renormalization-group improved inflationary scalar electrodynamics and SU(5) scenarios confronted with Planck 2013 and BICEP2 results
Elizalde, E.; Odintsov, S. D.; Pozdeeva, E. O. +1 more
The possibility to construct inflationary models for the renormalization-group (RG) improved potentials corresponding to scalar electrodynamics and to SU(2) and SU(5) models is investigated. In all cases, the tree-level potential, which corresponds to the cosmological constant in the Einstein frame, is seen to be nonsuitable for inflation. Rather …