118360717
Inflation and alternatives with blue tensor spectra
We study the tilt of the primordial gravitational waves spectrum. A hint of blue tilt is shown from analyzing the BICEP2 and POLARBEAR data. Motivated by this, we explore the possibilities of blue tensor spectra from the very early universe cosmology models, including null energy condition violating inflation, inflation with general initial conditions, and string gas cosmology, etc. For the simplest G-inflation, blue tensor spectrum also implies blue scalar spectrum. In general, the inflation models with blue tensor spectra indicate large non-Gaussianities. On the other hand, string gas cosmology predicts blue tensor spectrum with highly Gaussian fluctuations. If further experiments do confirm the blue tensor spectrum, non-Gaussianity becomes a distinguishing test between inflation and alternatives.
17457342
Curvaton dynamics and the non-linearity parameters in the curvaton model
We investigate the curvaton dynamics and the non-linearity parameters in the curvaton model with a potential slightly deviating from the quadratic form in detail. The non-linearity parameter gNL will show up due to the curvaton self-interaction. We also point out that the leading order of the non-quadratic term in the curvaton potential can be negative, for example in the axion-type curvaton model. If a large positive gNL is detected, the axion-type curvaton model will be preferred.
119270914
Quadra-Spectrum and Quint-Spectrum from Inflation and Curvaton Models
We calculate the quadra-spectrum and quint-spectrum, corresponding to five and six point correlation functions of the curvature perturbation. For single field inflation with standard kinetic term, the quadra-spectrum and quint-spectrum are small, which are suppressed by slow roll parameters. The calculation can be generalized to multiple fields. When there is no entropy perturbation, the quadra-spectrum and quint-spectrum are suppressed as well. With the presence of entropy perturbation, the quadra-spectrum and quint-spectrum can get boosted. We illustrate this boost in the multi-brid inflation model. For the curvaton scenario, the quadra-spectrum and quint-spectrum are also large in the small r limit. We also calculate representative terms of quadra-spectrum and quint-spectrum for inflation with generalized kinetic terms, and estimate their order of magnitude for quasi-single field inflation.
118533325
Quasi-Single Field Inflation and Non-Gaussianities
In quasi-single field inflation models, massive isocurvature modes, that are coupled to the inflaton and have mass of order the Hubble parameter, can have nontrivial impacts on density perturbations, especially non-Gaussianities. We study a simple example of quasi-single field inflation in terms of turning inflaton trajectory. Large bispectra with a one-parameter family of novel shapes arise, lying between the well-known local and equilateral shape. The trispectra can also be very large and its magnitude tNL can be much larger than fNL2.
119112752
CMB statistical anisotropies of classical and quantum origins
We examine the impact of different anisotropic relics on inflation, in particular the predictions on the density perturbations. These relics can be the source of the large scale anomalies in the cosmic microwave background. There are two different types of background relics, one from the matter sector and the other purely from the metric. Although the angular-dependence of the statistical anisotropy in both cases are degenerate, the scale-dependence are observationally distinctive. In addition, we demonstrate that non-Bunch-Davies vacuum states can extend the statistical anisotropy to much shorter scales, and leave a scale-dependence that is insensitive to the different backgrounds but sensitive to the initial quantum state.
2921220
Non-Gaussianity, isocurvature perturbation, gravitational waves, and a no-go theorem for the isocurvaton
We investigate the isocurvaton model, in which the isocurvature perturbation plays a role in suppressing the curvature perturbation, and large non-Gaussianity and gravitational waves can be produced with no isocurvature perturbation for dark matter. We show that in the slow-roll noninteracting multifield theory, the isocurvaton mechanism cannot be realized. This result can also be generalized to most of the studied models with generalized kinetic terms. We also study the implications for the curvaton model. We show that there is a combined constraint for curvaton on non-Gaussianity, gravitational waves, and isocurvature perturbation. The technique used in this paper can also help to simplify some calculations in the mixed inflaton and curvaton models. We also investigate the possibility of producing large negative non-Gaussianity and nonlocal non-Gaussianity in the curvaton model.
118370851
Modeling of the IUCF cooler synchrotron
Measurements of lattice parameters for the Indiana University Cyclotron Facility (IUCF) Cooler synchrotron at betatron tunes close to a sum resonance line are discussed. The measured beta functions at 36 quadrupole locations and the dispersion functions at 35 Beam Position Monitor (BPM) locations are compared with calculations. The methods used to make the above measurements and the data analysis are described.
118327242
Inhomogeneous and Interacting Vacuum Energy
Vacuum energy is a simple model for dark energy driving an accelerated expansion of the universe. If the vacuum energy is inhomogeneous in spacetime then it must be interacting. We present the general equations for a spacetime-dependent vacuum energy in cosmology, including inhomogeneous perturbations. We show how any dark energy cosmology can be described by an interacting vacuum+matter. Different models for the interaction can lead to different behaviour (e.g., sound speed for dark energy perturbations) and hence could be distinguished by cosmological observations. As an example we present the cosmic microwave microwave background anisotropies and the matter power spectrum for two different versions of a generalised Chaplygin gas cosmology.
18345543
A Measurement of the Primordial Power Spectrum from Maxima and Boomerang Data
Model-independent measurements of the primordial power spectrum of matter density fluctuations provide a unique probe of physics in the very early universe, and can provide powerful constraints on inflationary models. We parametrize the primordial power spectrum A2s(k) as an arbitrary function, and measure its binned amplitude from the cosmic microwave background radiation anisotropy (CMB) data from Maxima and Boomerang. We find that for a flat universe with A2s(k) = 1 (scale-invariant) for scales k < 0.001 h/Mpc, the primordial power spectrum deviates significantly from a scale-invariant HarrisonZeldovich spectrum. It has a drop in power at 0.001 h/Mpc < ∼ k < ∼ 0.01 h/Mpc, and a rise in power at 0.01 h/Mpc < ∼ k < ∼ 0.1 h/Mpc, with the general trend of less power on small scales compared to a scale-invariant power spectrum. Our results are consistent with large scale structure data, and seem to suggest that unusual physics may have occurred in the very early universe. At the dawn of the new millennium, the inflationary paradigm appears the most plausible solution to the problems of the standard cosmology, and consistent with all current observational data. However, we are still far from establishing a definitive model of inflation. There currently exists a broad range of inflationary models (Kolb 1997, Turner 1997), many of which appear consistent with observational data. Model-independent measurements of the primordial power spectrum of matter density fluctuations can provide unique and powerful constraints on inflationary models. Although it has been conventional to take the primordial power spectrum to be a featureless power law in analyzing cosmological data, there are both theoretical and observational reasons to allow the primordial power spectrum to be a free function.
122759337
A measurement of the Z0 leptonic partial widths and the vector and axial vector coupling constants
Abstract We have measured the partial widths of the Z 0 into lepton pairs, and the forward-backward charge asymmetry for the process e + e − → μ + μ − using the L3 detector at LEP. We obtain an average Γ ll of 83.0±2.1±1.1 MeV.From this result and the asymmetry measurement, we extract the values of the vector and axial vector couplings of the Z 0 to leptons: g rmv =−0.066 −0.027 +0.046 and g rmA = −0.495 −0.007 +0.007 .
118795067
The WFIRST Galaxy Survey Exposure Time Calculator
This document describes the exposure time calculator for the Wide-Field Infrared Survey Telescope (WFIRST) high-latitude survey. The calculator works in both imaging and spectroscopic modes. In addition to the standard ETC functions (e.g. background and S/N determination), the calculator integrates over the galaxy population and forecasts the density and redshift distribution of galaxy shapes usable for weak lensing (in imaging mode) and the detected emission lines (in spectroscopic mode). The source code is made available for public use.