119300679
The TT, TB, EB and BB correlations in anisotropic inflation
The ongoing and future experiments will measure the B-mode from different sky coverage and frequency bands, with the potential to reveal non-trivial features in polarization map. In this work we study the TT, TB, EB and BB correlations associated with the B-mode polarization of CMB map in models of charged anisotropic inflation. The model contains a chaotic-type large field complex inflaton which is charged under the U(1) gauge field. We calculate the statistical anisotropies generated in the power spectra of the curvature perturbation, the tensor perturbation and their cross-correlation. It is shown that the asymmetry in tensor power spectrum is a very sensitive probe of the gauge coupling. While the level of statistical anisotropy in temperature power spectrum can be small and satisfy the observational bounds, the interactions from the gauge coupling can induce large directional dependence in tensor modes. This will leave interesting anisotropic fingerprints in various correlations involving the B-mode polarization such as the TB cross-correlation which may be detected in upcoming Planck polarization data. In addition, the TT correlation receives an anisotropic contribution from the tensor sector which naturally decays after l ∼> 100. We expect that the mechanism of using tensor sector to induce asymmetry at low lmore » to be generic which can also be applied to address other low l CMB anomalies.« less
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.
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.
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.
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.
122914096
The design and mass production on resistive plate chambers for the BESIII experiment
A new type of the phenolic paper laminate is used as the resistive electrodes of BESIII RPC. The surface smoothness of these laminates is comparable to that of the bakelite plates with linseed oil treating. A technique to adjust the bulk resistivity of the laminates within the range of 10 9 –10 13 O cm is developed. Nowadays, about 1000 bare chambers (1200 m 2 ) have been produced and used for BESIII MUON, and the rejection rate is only 1.5%. In this paper, we will discuss the mass production and quality control procedures of these RPCs. r 2007 Elsevier B.V. All rights reserved. PACS: 29.40.n; 29.30.Cs
125390776
Neutrino Oscillation: Non-Accelerator Experiments
In recent years, major advances have been seen in neutrino oscillation studies. In this talk, I will cover latest results by using solar neutrinos, atmospheric neutrinos and reactor neutrinos. Improved precision of oscillation parameters, including 12, M21, 23 and M32 are reported. The last unknown oscillation parameters 13, M31 are known now. The next generation reactor neutrino experiments will be able to determine the mass hierarchy and improve significantly the precision of 12, M21, and M32. Experiments to study sterile neutrinos are under-planning using reactor neutrinos, radioactive sources as well as accelerator neutrinos.
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.
17382364
The Cross-Correlation between Galaxies of Different Luminosities and Colors
We study the cross-correlation between galaxies of different luminosities and colors, using a sample of 284,489 galaxies selected from SDSS DR4. Galaxies are divided into six samples according to luminosity, and each of these samples is further divided into red and blue subsamples according to their (g-r) colors. Projected autocorrelation is estimated for each subsample, and projected cross-correlation is estimated for each pair of subsamples. At projected separations r(p) greater than or similar to 1 h(-1) Mpc, all correlation functions are roughly parallel, although the correlation amplitude depends systematically on both luminosity and color. On r(p) less than or similar to 1 h(-1) Mpc, the autocorrelation and cross- correlation functions of red galaxies are significantly enhanced relative to the corresponding power laws obtained on larger scales. Such enhancement is absent for blue galaxies and in the cross- correlation between red and blue galaxies. We estimate the relative bias factor on scales r(p) greater than or similar to 1 h(-1) Mpc for each subsample using its autocorrelation function as well as its cross-correlation functions with other subsamples. The relative bias factors obtained from different methods are similar. For blue galaxies the luminosity dependence of the relative bias is strong over the entire luminosity range probed (-23.0 < M-r <= -18.0), while for red galaxies the dependence is weaker and becomes insignificant for luminosities below L*. In order to examine whether a significant stochastic/nonlinear component exists in the bias relation, we study the ratio R-ij equivalent to WiiWjj/W-ij(2), where W-ij is the projected correlation between subsample "i" and "j." Results suggest that a significant stochastic/nonlinear component exists in the relationship between red and blue galaxies, particularly on small scales.
1288334
Model-independent measurement of the primordial power spectrum
In inflationary models with minimal amount of gravity waves, the primordial power spectrum of density fluctuations, AS2(k), together with the basic cosmological parameters, completely specify the predictions for the cosmic microwave background (CMB) anisotropy and large scale structure. Here we show how we can strongly constrain both AS2(k) and the cosmological parameters by combining the data from the Microwave Anisotropy Probe (MAP) and the galaxy redshift survey from the Sloan Digital Sky Survey (SDSS). We allow AS2(k) to be a free function, and thus probe features in the primordial power spectrum on all scales. MAP and SDSS have scale-dependent measurement errors that decrease in opposite directions on astrophysically interesting scales; they complement each other and allow the measurement of the primordial power spectrum independent of inflationary models, giving us valuable information on physics in the early Universe, and providing clues to the correct inflationary model.