Probing for the Cosmological Parameters with PLANCK Measurement

We investigate the constraints on cosmological parameters especially for EoS of dark energy, inflationary parameters, neutrino mass and curvature of universe using simulated Planck data. Firstly we determine cosmological parameters with current observations including ESSENCE, WMAP3, Boomerang-2K2, CBI, VSA, ACBAR, SDSS LRG and 2dFGRS, and take best-fit model as the fiducial model in simulations. In simulations we pay attention to the effects of dynamical dark energy in determination of cosmological parameters. We add simulated SNAP data to do all the simulations. Using present data, we find Quintom dark energy model is mildly favored while \LambdaCDM remains a good fit. In the framework of dynamical dark energy, the constraints on inflationary parameters, m_{\nu} and \Omega_{K} become weak compared with the constraints in \LambdaCDM. Intriguingly, we find that the inflationary models with a "blue" tilt, which are excluded about 2\sigma in \LambdaCDM model, are well within 2\sigma region with the presence of the dynamics of dark energy. The upper limits of neutrino mass are weakened by a factor of 2 (95% C.L.), say, m_{\nu}<1.59 eV and m_{\nu}<1.53 eV for two forms of parametrization of the equation of state of dark energy. The flat universe is a good fit to the current data, namely, |\Omega_{K}|<0.03 (95% C.L.). With the simulated Planck and SNAP data, dynamical dark energy and \LambdaCDM might be distinguished at 4\sigma. And uncertainties of inflationary parameters, m_{\nu} and \Omega_{K} can be reduced obviously. We also constrain the rotation angle \Delta\alpha, denoting possible cosmological CPT violation, with simulated Planck and CMBpol data and find that our results are much more stringent than current constraint and will verify cosmological CPT symmetry with a higher precision. (Abridged)Comment: 15 pages, 8 figures and 3 tables, Accepted for publication in Int.J.Mod.Phys.

Determining Cosmological Parameters with Latest Observational Data

In this paper, we combine the latest observational data, including the WMAP five-year data (WMAP5), BOOMERanG, CBI, VSA, ACBAR, as well as the Baryon Acoustic Oscillations (BAO) and Type Ia Supernoave (SN) "Union" compilation (307 sample) to determine the cosmological parameters. Our results show that the $\Lambda$CDM model remains a good fit to the current data. In a flat universe, we obtain the tight limit on the constant EoS of dark energy as, $w=-0.977\pm0.056$ ($1 \sigma$). For the dynamical dark energy models with time evolving EoS, we find that the best-fit values are $w_0=-1.08$ and $w_1=0.368$, implying the preference of Quintom model whose EoS gets across the cosmological constant boundary. For the curvature of universe, our results give $-0.012<\Omega_k<0.009$ (95% C.L.) when fixing w_{\DE}=-1. When considering the dynamics of dark energy, the flat universe is still a good fit to the current data. Regarding the neutrino mass limit, we obtain the upper limits, $\sum m_{\nu}<0.533$ eV (95% C.L.) within the framework of the flat $\Lambda$CDM model. When adding the SDSS Lyman-$\alpha$ forest power spectrum data, the constraint on $\sum m_{\nu}$ can be significantly improved, $\sum m_{\nu}<0.161$ eV (95% C.L.). Assuming that the primordial fluctuations are adiabatic with a power law spectrum, within the $\Lambda$CDM model, we find that the upper limit on the ratio of the tensor to scalar is $r<0.200$ (95% C.L.) and the inflationary models with the slope $n_s\geq1$ are excluded at more than $2 \sigma$ confidence level. However, in the framework of dynamical dark energy models, the allowed region in the parameter space of ($n_s$,$r$) is enlarged significantly. Finally, we find no evidence for the large running of the spectral index. (Abridged)Comment: 8 pages, 5 figures, 2 tables, More discussion on NE

An efficient probe of the cosmological CPT violation

We develop an efficient method based on the linear regression algorithm to probe the cosmological CPT violation using the CMB polarisation data. We validate this method using simulated CMB data and apply it to recent CMB observations. We find that a combined data sample of BICEP1 and BOOMERanG 2003 favours a nonzero isotropic rotation angle at $2.3\sigma$ confidence level, ie, $\Delta\alpha=-3.3 \pm1.4$ deg (68% CL) with systematics included.Comment: 10 pages, 5 figures, 2 tables. The published versio

Microscopic investigation of one- and two-proton decay from the excited states of 10C

We present microscopic cluster model calculations for the 1p and 2p decays of the 0+2 and 2+2 states of 10C. With the R-matrix method, we have estimated the decay widths. The obtained 1p and 2p decay widths are in good agreement with the recent experimental data and support the validity of the di-proton approximation for the 2p decay of 10C(0+2). We also show the suppression of the 1p decay of the 10C(0+2) state due to the structure mismatch with the decay channel

Testing CPT Symmetry with CMB Measurements: Update after WMAP5

In this Letter we update our previous result on the test of CPT symmetry with Cosmic Microwave Background (CMB) measurements. A CPT violating interaction in the photon sector ${\cal L}_{cs} \sim p_{\mu}A_{\nu}\tilde F^{\mu\nu}$ gives rise to a rotation of the polarization vectors of the propagating CMB photons. Recently the WMAP group used the newly released polarization data of WMAP5 to measure this rotation angle $\Delta\alpha$ and obtained $\Delta\alpha=-1.7\pm2.1$ deg ($1\sigma$). However, in their analysis the BOOMERanG 2003 data is not included. Here we revisit this issue by combining the full data of WMAP5 and BOOMERanG 2003 angular power spectra for the measurement of this rotation angle $\Delta\alpha$ and find that $\Delta\alpha=-2.6\pm1.9$ deg at a 68% confidence level.Comment: 3 pages, 1 figure, Some typos are correcte