Towards a warped inflationary brane scanning

We present a detailed systematics for comparing warped brane inflation with the observations, incorporating the effects of both moduli stabilization and ultraviolet bulk physics. We explicitly construct an example of the inflaton potential governing the motion of a mobile D3 brane in the entire warped deformed conifold. This allows us to precisely identify the corresponding scales of the cosmic microwave background. The effects due to bulk fluxes or localized sources are parametrized using gauge/string duality. We next perform some sample scannings to explore the parameter space of the complete potential, and first demonstrate that without the bulk effects there can be large degenerate sets of parameters with observationally consistent predictions. When the bulk perturbations are included, however, the observational predictions are generally spoiled. For them to remain consistent, the magnitudes of the bulk effects need to be highly suppressed via fine tuning.Comment: (v1) 11 pages, 2 figures, 2 tables; (v2) more clarifications and references added; (v3) 12 pages, more discussions, to appear in Physical Review

Breaking scale invariance from a singular inflaton potential

In this paper we break the scale invariance of the primordial power spectrum of curvature perturbations of inflation. Introducing a singular behaviour due to spontaneous symmetry breaking in the inflaton potential, we obtain fully analytic expressions of scale dependent oscillation and a modulation in power on small scale in the primordial spectrum. And we give the associated cosmic microwave background and matter power spectra which we can observe now and discuss the signature of the scale dependence. We also address the possibility of whether some inflationary model with featured potential might mimic the predictions of the scale invariant power spectrum. We present some examples which illustrate such degeneracies.Comment: 20 pages, 9 figures; Discussion expanded and references added; Miscellaneous typos correcte

Inflation in minimal left-right symmetric model with spontaneous D-parity breaking

We present a simplest inflationary scenario in the minimal left-right symmetric model with spontaneous D-parity breaking, which is a well motivated particle physics model for neutrino masses. This leads us to connect the observed anisotropies in the cosmic microwave background to the sub-eV neutrino masses. The baryon asymmetry via the leptogenesis route is also discussed briefly.Comment: (v1) 4 pages, 1 figure; (v2) typos corrected; (v3) title and abstract changed, numerical estimates given, minor changes; (v4) 5 pages, relations between the neutrino masses and the CMB fluctuations become more explicit, miscellaneous changes, to appear in Physical Review

Sustainability of multi-field inflation and bound on string scale

We study the effects of the interaction terms between the inflaton fields on the inflationary dynamics in multi-field models. With power law type potential and interactions, the total number of e-folds may get considerably reduced and can lead to unacceptably short period of inflation. Also we point out that this can place a bound on the characteristic scale of the underlying theory such as string theory. Using a simple multi-field chaotic inflation model from string theory, the string scale is constrained to be larger than the scale of grand unified theory.Comment: (v1) 9 pages, 1 figure;(v2) 10 pages, references added; (v3) 15 pages, 4 figures, more discussions about parameters and observable quantities, references added, to appear in Modern Physics Letters

Inflationary Hubble Parameter from the Gravitational Wave Spectrum in the General Slow-roll Approximation

Improved general slow-roll formulae giving the primordial gravitational wave spectrum are derived in the present work. Also the first and second order general slow-roll inverse formulae giving the Hubble parameter $H$ in terms of the gravitational wave spectrum are derived. Moreover, the general slow-roll consistency condition relating the scalar and tensor spectra is obtained

New constraints on the observable inflaton potential from WMAP and SDSS

We derive some new constraints on single-field inflation from the Wilkinson Microwave Anisotropy Probe 3-year data combined with the Sloan Luminous Red Galaxy survey. Our work differs from previous analyses by focusing only on the observable part of the inflaton potential, or in other words, by making absolutely no assumption about extrapolation of the potential from its observable region to its minimum (i.e., about the branch of the potential responsible for the last ~50 inflationary e-folds). We only assume that inflation starts at least a few e-folds before the observable Universe leaves the Hubble radius, and that the inflaton rolls down a monotonic and regular potential, with no sharp features or phase transitions. We Taylor-expand the inflaton potential at order v=2, 3 or 4 in the vicinity of the pivot scale, compute the primordial spectra of scalar and tensor perturbations numerically and fit the data. For v>2, a large fraction of the allowed models is found to produce a large negative running of the scalar tilt, and to fall in a region of parameter space where the second-order slow-roll formalism is strongly inaccurate. We release a code for the computation of inflationary perturbations which is compatible with CosmoMC.Comment: 10 pages, 6 figures, codes available at http://wwwlapp.in2p3.fr/~lesgourgues/inflation/. Version to be published in Phys.Rev.

When is Quantum Decoherence Dynamics Classical?

A direct classical analog of quantum decoherence is introduced. Similarities and differences between decoherence dynamics examined quantum mechanically and classically are exposed via a second-order perturbative treatment and via a strong decoherence theory, showing a strong dependence on the nature of the system-environment coupling. For example, for the traditionally assumed linear coupling, the classical and quantum results are shown to be in exact agreement.Comment: 5 pages, no figures, to appear in Physical Review Letter

Variability of Contact Process in Complex Networks

We study numerically how the structures of distinct networks influence the epidemic dynamics in contact process. We first find that the variability difference between homogeneous and heterogeneous networks is very narrow, although the heterogeneous structures can induce the lighter prevalence. Contrary to non-community networks, strong community structures can cause the secondary outbreak of prevalence and two peaks of variability appeared. Especially in the local community, the extraordinarily large variability in early stage of the outbreak makes the prediction of epidemic spreading hard. Importantly, the bridgeness plays a significant role in the predictability, meaning the further distance of the initial seed to the bridgeness, the less accurate the predictability is. Also, we investigate the effect of different disease reaction mechanisms on variability, and find that the different reaction mechanisms will result in the distinct variabilities at the end of epidemic spreading.Comment: 6 pages, 4 figure

Non-Gaussianity from false vacuum inflation: Old curvaton scenario

We calculate the three-point correlation function of the comoving curvature perturbation generated during an inflationary epoch driven by false vacuum energy. We get a novel false vacuum shape bispectrum, which peaks in the equilateral limit. Using this result, we propose a scenario which we call "old curvaton". The shape of the resulting bispectrum lies between the local and the false vacuum shapes. In addition we have a large running of the spectral index.Comment: 13 pages, 3 figures; v2 with minor revison; v3 final version to appear on JCA