Inflation,quantum fields,and CMB anisotropies

Inflationary cosmology has proved to be the most successful at predicting the properties of the anisotropies observed in the cosmic microwave background (CMB). In this essay we show that quantum field renormalization significantly influences the generation of primordial perturbations and hence the expected measurable imprint of cosmological inflation on the CMB. However, the new predictions remain in agreement with observation, and in fact favor the simplest forms of inflation. In the near future, observations of the influence of gravitational waves from the early universe on the CMB will test our new predictions.     

Inflation in de Sitter spacetime and CMB large scale anomaly

The influence of cosmological constant-type dark energy in the early universe is investigated. This is accommodated by a new dispersion relation in de Sitter spacetime. We perform a global fit to explore the cosmological parameter space by using the Cosmo MC package with the recently released Planck TT and WMAP polarization datasets. Using the results from the global fit, we compute a new CMB temperature–temperature(TT) spectrum.The obtained TT spectrum has lower power compared with that based on the ΛCDM model at large scales.     

Correlated isocurvature fluctuation in quintessence and suppressed cosmic microwave background anisotropies at low multipoles

We consider cosmic microwave background (CMB) anisotropy in models with quintessence, taking into account isocurvature fluctuation. It is shown that, if the primordial fluctuation of the quintessence has a correlation with the adiabatic density fluctuations, the CMB angular power spectrum C(l) at low multipoles can be suppressed without affecting C(l) at high multipoles. A possible scenario for generating a correlated mixture of the quintessence and adiabatic fluctuations is also discussed.     

Inflation with hyperbolic potential in the braneworld model

In this paper we study inflationary dynamics with a scalar field in an inverse coshyperbolic potential in the braneworld model. We note that a sufficient inflation may be obtained with the potential considering slow-roll approximation in the high energy limit. We determine the minimum values of the initial inflaton field required to obtain sufficient inflation and also determine the relevant inflationary parameters. The numerical values of spectral index of the scalar perturbation spectrum are determined by varying the number of e-foldings for different initial values of the inflaton field. The result obtained here is in good agreement with the current observational limits.      

The Szekeres Swiss Cheese model and the CMB observations

This paper presents the application of the Szekeres Swiss Cheese model to the analysis of observations of the cosmic microwave background (CMB) radiation. The impact of inhomogeneous matter distribution on the CMB observations is in most cases studied within the linear perturbations of the Friedmann model. However, since the density contrast and the Weyl curvature within the cosmic structures are large, this issue is worth studying using another approach. The Szekeres model is an inhomogeneous, non-symmetrical and exact solution of the Einstein equations. In this model, light propagation and matter evolution can be exactly calculated, without such approximations as small amplitude of the density contrast. This allows to examine in more realistic manner the contribution of the light propagation effect to the measured CMB temperature fluctuations. The results of such analysis show that small-scale, non-linear inhomogeneities induce, via Rees-Sciama effect, temperature fluctuations of amplitude 10⁻⁷–10⁻⁵ on angular scale ϑ < 0.24° (ℓ > 750). This is still much smaller than the measured temperature fluctuations on this angular scale. However, local and uncompensated inhomogeneities can induce temperature fluctuations of amplitude as large as 10⁻³, and thus can be responsible the low multipoles anomalies observed in the angular CMB power spectrum.     

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.     

Inflation and reheating in the Starobinsky model with conformal HiggsField

This is a talk presented by A.A. Tokareva at Baikal summer school on physics of elementary particles and astrophysics 2012. We studied the reheating after the Starobinsky inflation and have found that the main process is the inflaton decay to SM gauge fields due to the conformal anomaly. The reheating temperature is low leading to the possibility to detect the gravity wave signal from inflation and evaporation of structures formed after inflation in DECIGO and BBO experiments. Also we give predictions for the parameters of scalar perturbation spectrum at the next-to-leading order of slow roll and obtain a bound on the Higgs mass.     

Inflation model selection revisited

We update the constraints on the power spectra of primordial curvature perturbation and tensor perturbation including Planck data 2015(P15) and recently released BICEP2/Keck data(BK15), Baryon Acoustic Oscillation data and the Type Ia supernovae data.We find that the upper limits of tensor-to-scalar ratio are 0.061, 0.064 and 0.072 at 95% confidence level(CL) in the ΛCDM+r,ΛCDM+r+α_s and ΛCDM+r+α_s+β_s models respectively, where αsand βsare the running of scalar spectral index and running of running. The inflation model with a concave potential is favored at more than 95% CL. In addition, parametrizing the slow-roll parameter ? ～ 1/N~p, where N is the e-folding number before the end of inflation and taken in the range of [50, 60] and [14, 75]respectively, we conclude that the inflation model with a monomial potential V(?) ～ ?~n is disfavored at more than 95% CL, and both the Starobinsky inflation model and brane inflation model are still consistent with the data.     

Anomalously suppressed localization in the two-channel Anderson model

We study numerically the localization properties of a two-channel quasi-one-dimensional Anderson model with uncorrelated diagonal disorder within the nearest-neighbor tight-binding approximation. We calculate and analyze the disorder-averaged transmittance and the Lyapunov exponent. We find that the localization of the entire system is enhanced by increasing the interchain hopping strength t?. From the numerical investigation of the energy dependence of the Lyapunov exponent for many different interchain hopping strengths, we find that apart from the band center anomaly, which usually occurs in strictly one-dimensional disordered systems, additional anomalies appear at special spectral points. They are found to be associated with the interchain hopping strength and occur at E = ± t?/2 and ± t?. We find that the anomalies at E = ± t? are associated with the π-coupling occurring within one energy band and those at E = ± t?/2 are associated with the π-coupling occurring between two different energy bands. Despite having a similar origin, these two anomalies have distinct characteristics in their dependence on the strength of disorder. We also show that for a suitable range of parameter values, effectively delocalized states are observed in finite-size systems.     

Weak lensing of the CMB

The cosmic microwave background (CMB) represents a unique source for the study of gravitational lensing. It is extended across the entire sky, partially polarized, located at the extreme distance of z = 1,100, and is thought to have the simple, underlying statistics of a Gaussian random field. Here we review the weak lensing of the CMB, highlighting the aspects which differentiate it from the weak lensing of other sources, such as galaxies. We discuss the statistics of the lensing deflection field which remaps the CMB, and the corresponding effect on the power spectra. We then focus on methods for reconstructing the lensing deflections, describing efficient quadratic maximum-likelihood estimators and delensing. We end by reviewing recent detections and observational prospects.     

Inflation with improved D3-brane potential and the fine tunings associated with the model

We revisit our earlier investigations of the brane–antibrane inflation in a warped deformed conifold background, reported in Phys. Lett. B 674, 131 (2009), where now we include the contributions to the inflation potential arising from imaginary anti-self-dual (IASD) fluxes including the term with irrational scaling dimension discovered recently in  and . We observe that these corrections to the effective potential help in relaxing the severe fine tunings associated with the earlier analysis. Required number of e-folds, observational constraint on COBE normalization and low value of the tensor to scalar ratio are achieved which is consistent with WMAP seven years data.     

CMB: the isotropic part

The Cosmic Microwave Background, or CMB, is the only truly diffuse background, whereas the other backgrounds come from the integrated light (along the line of sight) of various sources. The CMB is now known, thanks to the FIRAS experiment above the COBE satellite, to have a nearly perfect blackbody spectrum. This proves to be quite constraining on early energy releases. We review the average spectrum of the CMB with respect to other backgrounds and the consequences regarding the history of the early Universe. To cite this article: F.R. Bouchet, J.-L. Puget, C. R. Physique 4 (2003).     

Mimicking trans-Planckian effects in the CMB with conventional physics

We investigate the possibility that fields coupled to the inflaton can influence the primordial spectrum of density perturbations through their coherent motion. For example, the second field in hybrid inflation might be oscillating at the beginning of inflation rather than at the minimum of its potential. Although this effect is washed out if inflation lasts long enough, we note that there can be up to 30e-foldings of inflation prior to horizon crossing of COBE fluctuations while still giving a potentially visible distortion. Such pumping of the inflaton fluctuations by purely conventional physics can resemble trans-Planckian effects which have been widely discussed. The distortions which they make to the CMB could leave a distinctive signature which differs from generic effects like tilting of the spectrum.     

Electrostatics of the point dipole and higher multipoles

It is shown that a distribution theory form for the electrostatics of point multipoles can be constructed, which reduces to the usual theory away from the position of the multipole, but in which the total electromagnetic self-energy is zero and the self-force density is zero.     

Weak gravitational lensing of the CMB

Weak gravitational lensing has several important effects on the cosmic microwave background (CMB): it changes the CMB power spectra, induces non-Gaussianities, and generates a B-mode polarization signal that is an important source of confusion for the signal from primordial gravitational waves. The lensing signal can also be used to help constrain cosmological parameters and lensing mass distributions. We review the origin and calculation of these effects. Topics include: lensing in General Relativity, the lensing potential, lensed temperature and polarization power spectra, implications for constraining inflation, non-Gaussian structure, reconstruction of the lensing potential, delensing, sky curvature corrections, simulations, cosmological parameter estimation, cluster mass reconstruction, and moving lenses/dipole lensing.     

Brillouin scattering and the CMB

Brillouin scattering of photons off the density fluctuations in a fluid is potentially important for cosmology. We derive the Brillouin spectral distortion of blackbody radiation, and discuss the possible implications for the cosmic microwave background. The thermal Sunyaev-Zeldovich effect is slightly modified by Brillouin distortion, but only at very long wavelengths.     

Inflation with superstrings

Cosmological solutions with three exponentially expanding space dimensions in the N=1 supersymmetric Yang-Mills supergravity system are found under the assumption of gluino and “subgravitino” condensation. The potential has a long flat region providing sufficient inflation.