Primordial gravitational waves,BICEP2 and beyond

Observations of the imprints of primordial gravitational waves on the anisotropies in the cosmic microwave background can provide us with unambiguous clues to the physics of the very early Universe. In this brief article, the implications of the detection of such signatures for the inflationary scenario has been discussed.     

Cosmological parameter fittings with the BICEP2 data

Combining the latest Planck,Wilkinson Microwave Anisotropy Probe(WMAP),and baryon acoustic oscillation(BAO)data,we exploit the recent cosmic microwave background(CMB)B-mode power spectra data released by the BICEP2 collaboration to constrain the cosmological parameters of the ACDM model,especially the primordial power spectra parameters of the scalar and the tensor modes,ns,s,r,nt.We obtain constraints on the parameters for a lensed ACDM model using the Markov Chain Monte Carlo(MCMC)technique,the marginalized 68%bounds are r=0.03070.09140.1043,ns=0.00610.00610.9617,s=0.01050.00970.0175,nt=0.45150.45790.5198.We find that a blue tilt for nt is favored slightly,but it is still well consistent with flat or even red tilt.Our r value is slightly smaller than the one obtained by the BICEP group,in that we permit nt as a free parameter without imposing the single-field slow roll inflation consistency relation.When we impose this relation,then r=0.04460.06090.2130.For most other parameters,the best fit values and measurement errors are not altered significantly by the introduction of the BICEP2 data.     

Weighing Neutrinos in f(R) Gravity in Light of BICEP2

We constrain the neutrino mass in f(R) gravity using the latest observations from the Planck, BAO and BICEP2 data. We find that the measurement on the B-modes can break the degeneracy between the massive neutrinos and the f(R) gravity. We find a non-zero value of the Compton wavelengths B0 at a 68% confidence level for the f(R) model in the presence of massive neutrinos when the BICEP2 data is used. Furthermore, the tension on the tensor-to-scalar ratios between the measured values from Plank and BICEP2 is significantly reconciled in our model.     

Weighing Neutrinos in f(R) Gravity in Light of BICEP2

We constrain the neutrino mass in f(R) gravity using the latest observations from the Planck, BAO and BICEP2 data. We find that the measurement on the B-modes can break the degeneracy between the massive neutrinos and the f(R) gravity. We find a non-zero value of the Compton wavelengths B₀ at a 68% confidence level for the f(R) model in the presence of massive neutrinos when the BICEP2 data is used. Furthermore, the tension on the tensor-to-scalar ratios between the measured values from Plank and BICEP2 is significantly reconciled in our model.     

SUSY see-saw and NMSO(10)GUT inflation after BICEP2

Supersymmetric see-saw slow roll inflection point inflation occurs along a MSSM D-flat direction associated with gauge invariant combination of Higgs, slepton and right-handed sneutrino at a scale set by the right-handed neutrino mass \(M_{{\nu }^{c}} \sim 10^{6}\!\,-\,\!10^{13}\) GeV. The tensor to scalar perturbation ratio r～10^?3 can be achieved in this scenario. However, this scenario faced difficulty in being embedded in the realistic new minimal supersymmetric SO(10) grand unified theory (NMSO(10)GUT). The recent discovery of B-mode polarization by BICEP2, changes the prospects of NMSO(10)GUT inflation. Inflection point models become strongly disfavoured, as the trilinear coupling of SUSY see-saw inflation potential gets suppressed relative to the mass parameter favoured by BICEP2. Large values of r≈0.2 can be achieved with super-Planck scale inflaton values and mass scales of inflaton ≥10 ¹³ GeV. In NMSO(10)GUT, this can be made possible with an admixture of heavy Higgs doublet fields, i.e., other than MSSM Higgs field, which are present and have masses of order GUT scale.     

Gaussian Fitting Parameters of the ESA PLANCK HFI Beams

We present Gaussian fitting parameters of simulated beams of the High Frequency Instrument (HFI) of the ESA PLANCK mission. This space probe is designed for measuring the anisotropy of temperature and polarization of the Cosmic Microwave Background (CMB). The six HFI spectral bands cover the frequency range 0.1 - 1 THz with 52 bolometers. Their beams are computed by multi-mode physical optics propagation of the source field from the apertures of the horns simulated by the scattering matrix approach. Computed power patterns are fitted by the elliptical Gaussian beams minimizing the peak difference between the two power distributions within the beam. This approximation is generally considered as acceptable from the scientific viewpoint, although we show that induced errors are far from negligible.     

Inflation and the Rotation Problem

The effect of an inflaton scalar field on cosmic rotation is discussed. It is shown that any physically reasonable inflaton scalar will dilute the cosmic vorticity by a factor of R^?3γ when the false vacuum decays into matter. Since vorticity decays during inflation as R^3γ-5, this leads to a total decay by a factor of R⁵, which is not dependent on the equation of state of the rotating non-vacuum component of the energy-momentum tensor.     

Fast Physical Optics Simulations of the Multi-Beam Dual-Reflector Submillimeter-Wave Telescope on the ESA PLANCK Surveyor

We present physical optics simulations of the multi-beam dual-reflector submillimeter-wave telescope on the ESA PLANCK surveyor designed for measuring the temperature anisotropies and polarization characteristics of the cosmic microwave background. The telescope is of a non-conventional Gregorian configuration, with two ellipsoidal reflectors providing a very large field of view at the focal plane where the array of 76 horn antennas feeding low-temperature detectors is located. We analyse the defocusing effects of the system, the polarization properties of the telescope, and the optical performance of the high-frequency channels based on special multi-moded horns operating at 545 and 857 GHz.     

Inflation in the Einstein-Cartan cosmological model

All the three primordial phases of the universe, required by inflation, plus what is believed to be the present phase, have been studied in the Einstein-Cartan cosmological model in a Bianchi type I metric.     

Baryogenesis in Fresh Inflation

I study the possibility of baryogenesis can take place in fresh inflation. I find that it is possible that violation of baryon number conservation can occur during the period out-of-equilibrium in this scenario. Indeed, baryogenesis could be possible in the range of times (10⁹ – 10¹²) G^1/2, before the thermal equilibrium is restored at the end of fresh inflation.     

Inflation in warped geometries

We argue that brane anti-brane inflation in string theory de-Sitter vacua of Kachru–Kallosh–Linde–Trivedi (KKLT) is captured by the dynamics of a D3-brane probe in the local KKLT model constructed in hep-th/0203041. This provides a framework to study in a controllable way corrections to the inflationary slow roll parameter η due to conformal symmetry breaking in a warped geometry throat. We compute the leading correction to η for the inflation in the Klebanov–Tseytlin throat geometry. We find that in certain regime this correction tends to decrease η. Computations in a different regime suggest however that it is unlikely that η1 can be achieved with the D3-brane throat inflation.     

Inflation and axion cosmology

It is argued that the standard constraint ƒ⪷10¹²GeV in the axion theory and related constraints in the theories of other weakly interacting scalar fields do not apply in many versions of the inflationary universe scenario.     

Black Holes and Inflation

A model for black hole collapse and evaporation in which the black hole is supposed to be an excited state of one of the Planck black holes pervading the structure of spacetime is discussed. By assuming a Coleman-Weinberg gravitational effective potential for a scalar field inside the collapse matter, it is shown that the black hole state cannot be attained neither through bubble tunneling nor by the rolling down of the field.