Inflationary models predict a definite, model independent, angular dependence for the three-point correlation function of ∆T /T at large angles ( > ∼ 1 • ) which we calculate. The overall amplitude is model dependent and generically unobservably small, but may be large in some specific models. We compare our results with other models of nongaussian fluctuations.

We calculate the baryon asymmetry created by the decay of a pseudo Nambu-Goldstone boson ͑PNGB͒ whose interactions violate baryon number conservation. Our results are in disagreement with previous results in the original spontaneous baryogenesis models for the asymmetry produced by the decay of an oscillating scalar field with B-number-violating derivative couplings; we find that the net baryon number density is proportional to i 3 , where i is the amplitude of the PNGB field in natural inflation at the onset of reheating. While our calculation of the asymmetry is carried out in the context of natural inflation our approach is generally valid for baryogenesis models using decaying classical fields. We include a complete derivation of the number density of particles produced by the decay of a classical scalar field. ͓S0556-2821͑97͒07422-5͔PACS number͑s͒: 98.80. Cq, 11.30.Fs, 14.80.Mz Below we discuss our concerns with this conclusion and present calculations for the specific case of Eq. ͑1.1͒; our results disagree with Eq. ͑1.2͒.

If the initial state of the inflaton field is taken to have a thermal distribution instead of the conventional zero particle vacuum state then the curvature power spectrum gets modified by a temperature dependent factor such that the fluctuation spectrum of the microwave background radiation is enhanced at larger angles. We compare this modified cosmic microwave background spectrum with Wilkinson microwave anisotropy probe data to obtain an upper bound on the temperature of the inflaton at the time our current horizon crossed the horizon during inflation. We further conclude that there must be additional -foldings of inflation beyond what is needed to solve the horizon problem.

We calculate the electroweak-like one-loop supersymmetric contributions to the rare and flavor-violating decay of the top quark into a charm quark and a gauge boson: t → cV , with V = γ, Z, g. We consider loops of both charginos and down-like squarks (where we identify and correct an error in the literature) and neutralinos and up-like squarks (which have not been calculated before). We also account for left-right and generational squark mixing. Our numerical results indicate that supersymmetric contributions to t → cV can be upto 5 orders of magnitude larger than their Standard Model counterparts. However, they still fall short of the sensitivity expected at the next-generation top-quark factories.

Precise measurements of the anisotropies in the cosmic microwave background enable us to do an accurate study on the form of the primordial power spectrum for a given set of cosmological parameters. In a previous paper [1], we implemented an improved (error sensitive) Richardson-Lucy deconvolution algorithm on the measured angular power spectrum from the first year of WMAP data to determine the primordial power spectrum assuming a concordance cosmological model. This recovered spectrum has a likelihood far better than a scale invariant, or, 'best fit' scale free spectra (∆ ln L ≈ 25 w.r.t. Harrison Zeldovich, and, ∆ ln L ≈ 11 w.r.t. power law with ns = 0.95). In this paper we use Discrete Wavelet Transform (DWT) to decompose the local features of the recovered spectrum individually to study their effect and significance on the recovered angular power spectrum and hence the likelihood. We show that besides the infra-red cut off at the horizon scale, the associated features of the primordial power spectrum around the horizon have a significant effect on improving the likelihood. The strong features are localized at the horizon scale.

It has been argued in the past that in baryogenesis via out-of-equilibrium decays one must consider loop diagrams that contain more than one baryon number violating coupling. In this note we argue that the requirement with regard to baryon number violating couplings in loop diagrams is that the interaction between the intermediate on-shell particles and the final particles should correspond to a net change in baryon number and that this can be satisfied even if the loop diagram contains only one baryon number violating coupling. Put simply, we show that to create a baryon asymmetry there should be net B violation to the right of the 'cut' in the loop diagram. This is of relevance to some works involving the out-of-equilibrium decay scenario. *

We revisit the scenario where inflation is preceded by a radiation era by considering that the inflaton too could have been in thermal equilibrium early in the radiation era. Hence we take into account not only the effect of a pre-inflationary era on the inflaton mode functions but also that of a frozen thermal distribution of inflaton quanta. We initially discuss in detail the issues relevant to our scenario of a pre-inflationary radiation dominated era and then obtain the scalar power spectrum for this scenario. We find that the power spectrum is free from infrared divergences. We then use the WMAP and Planck data to determine the constraints on the inflaton comoving 'temperature' and on the duration of inflation. We find that the best fit value of the duration of inflation is less than 1 e-folding more than what is required to solve cosmological problems, while only an upper bound on the inflaton temperature can be obtained.1 Other attempts to explain the low power at low CMB multipoles involve non-trivial topologies of the universe [14][15][16][17][18][19][20][21][22], bouncing cosmologies [23,24], various inflationary scenarios (e.g. hybrid models of inflation [25], multi-field inflation [26], inflation which takes place in two stages [27][28][29] just enough inflation [30,31] which could take place in modified gravity theories [32] or preceded by a fast roll

We revisit the constraints that Planck 2015 temperature, polarization and lensing data impose on the parameters of warm inflation. To this end, we study warm inflation driven by a single scalar field with a quartic self interaction potential in the weak dissipative regime. We analyse the effect of the parameters of warm inflation, namely, the inflaton self coupling λ and the inflaton dissipation parameter Q P on the CMB angular power spectrum. We constrain λ and Q P for 50 and 60 number of e-foldings with the full Planck 2015 data (TT, TE, EE + lowP and lensing) by performing a Markov-Chain Monte Carlo analysis using the publicly available code CosmoMC and obtain the joint as well as marginalized distributions of those parameters. We present our results in the form of mean and 68 % confidence limits on the parameters and also highlight the degeneracy between λ and Q P in our analysis. From this analysis we show how warm inflation parameters can be well constrained using the Planck 2015 data.