118398040
Multi-stream inflation
We propose a ``multi-stream'' inflation model, which is a double field model with spontaneous breaking and restoration of an approximate symmetry. We calculate the density perturbation and non-Gaussianity in this model. We find that this model can have large, scale dependent, and probably oscillating non-Gaussianity. We also note that our model can produce features in the CMB power spectrum and hemispherical power asymmetry.
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.
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.
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.
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.
118677216
CMB Temperature and Matter Power Spectrum in a Decay Vacuum Dark Energy Model
In this paper, a decay vacuum model $\bar{\rho}_\Lambda=3\sigma M_p^2H_0 H$ is revisited by detailed analysis of background evolution and perturbation equations. We show the imprints on CMB temperature and matter power spectrum from the effective coupling terms between dark sectors by comparing to the standard cosmological constant model and observational data points (WMAP7 and SDSS DR7). We find that the decay vacuum model can describe the expansion rate at late times as well as the standard cosmological constant model but it fails to simultaneously reproduce the observed CMB and matter power spectrum. Its generalization $\bar{\rho}_\Lambda=3M_p^2(\xi_1 H_0 H+\xi_2 H^2)$ is also discussed. Detailed analysis of the background evolution shows that the dimensionless parameter $\xi_{2}$ would be zero to avoid the unnatural 'fine tuning' and to keep the positivity of energy density of dark matter and dark energy in the early epoch.
50843980
The BES-III experiment at the high luminosity Tau-Charm factory
Interesting results from BES-II and other experiments raised actually many new questions which shall be answered by its upgrade program, BEPCII and BES-III. The design and current status of BEPCII and BES-III are reported.
14068063
Updated Constraints on the Minimal Supergravity Model
We provide an up-to-date analysis of the parameter space of the minimal supergravity model (mSUGRA). Novel features include the new central value of the top quark mass, an improved calculation of the masses of the supersymmetric particles and the neutral Higgs bosons, constraints from b→sl+l− decays, and a careful treatment of the most important experimental and theoretical uncertainties. In addition to the by now traditional plots of the allowed region in the (m0,m1/2) plane, we show allowed regions in the planes spanned by pairs of physical sparticle or Higgs boson masses. Moreover, we search for the minimal allowed masses of new particles for various sets of constraints. We find that in many cases the direct experimental limits from collider and Dark Matter searches can be saturated even in this minimal model, and even after including the by now quite restrictive constraint on the Dark Matter relic density.
125302092
Measurements of the line shapes of D anti-D production and the ratio of the production rates of D+ D- and D0 anti-D0 in e+ e- annihilation at psi(3770) resonance
Abstract We report measurements of the line shapes of D + D − , D 0 D ¯ 0 and D D ¯ production as well as the line shape of the ratio of the production rates of D + D − and D 0 D ¯ 0 in e + e − annihilation at ψ ( 3770 ) resonance. We find that the line shapes of D + D − , D 0 D ¯ 0 and D D ¯ production are similar to an anomalous line shape of cross sections for e + e − → hadrons observed in the center-of-mass energy range from 3.70 to 3.87 GeV.
119301936
Integrated Sachs-Wolfe effect in time varying vacuum model
The integrated Sachs-Wolfe (ISW) effect is an important implication for dark energy. In this paper, we have calculated the power spectrum of the ISW effect in the time varying vacuum cosmological model, where the model parameter $\ensuremath{\beta}=4.407$ is obtained by the observational constraint of the growth rate. It is found that the source of the ISW effect is not only affected by the different evolutions of the Hubble function $H(a)$ and the dimensionless matter density ${\ensuremath{\Omega}}_{m}(a)$, but also by the different growth function ${D}_{+}(a)$, all of which are changed due to the presence of a matter production term in the time varying vacuum model. However, the difference of the ISW effect in the $\ensuremath{\Lambda}(t)\mathrm{CDM}$ model and the $\ensuremath{\Lambda}\mathrm{CDM}$ model is lessened to a certain extent because of the integration from the time of last scattering to the present. It is implied that the observations of the galaxies with high redshift are required to distinguish the two models.