Constraints on Dark Energy Models Including Gamma Ray Bursts

In this paper we analyze the constraints on the property of dark energy from cosmological observations. Together with SNe Ia Gold sample, WMAP, SDSS and 2dFGRS data, we include 69 long Gamma-Ray Bursts (GRBs) data in our study and perform global fitting using Markov Chain Monte Carlo (MCMC) technique. Dark energy perturbations are explicitly considered. We pay particular attention to the time evolution of the equation of state of dark energy parameterized as $w_{DE}=w_0+w_a(1-a)$ with $a$ the scale factor of the universe, emphasizing the complementarity of high redshift GRBs to other cosmological probes. It is found that the constraints on dark energy become stringent by taking into account high redshift GRBs, especially for $w_a$, which delineates the evolution of dark energy.Comment: 7 pages and 3 figures. Replaced with version accepted for publication in Phys. Lett.

Effects of metal film on transmission characteristics of single-dielectric-slab THz waveguide

The effects of a symmetrical metal film on the transmission characteristics of TM mode in the thicker single-dielectric-slab THz waveguide is analyzed theoretically. We find that the coating of metal film results in huge difference in the attenuation coefficients of TM mode, and it is increasing with respect to increase in the THz frequency. In case of a thicker single-dielectric-slab THz waveguide with low absorption loss, the influence of metal film on the loss of TM mode can not be ignored. We further study the influence of metal film on the mode field distribution of TM mode and we find that the mode field distribution of TM mode in the thicker dielectric slab is varied significantly after coating

THz wave transmission within the metal-clad antiresonant reflecting hollow waveguides

We present the transmission characteristics of THz waves in the metal-clad antiresonant reflecting hollow waveguides. We have derived the equation for the blueshift of the resonance frequency. The effects of the waveguide structure on the blueshift of the resonance frequency are studied comprehensively. In particular, we find that the blueshift of the resonance frequency is strongly affected by the interval between two dielectric slabs. By changing the interval, we obtain that the maximum frequency-tuning-range is up to 2030 GHz, and the maximum sensitivity of the resonance frequency shift is up to 6950 GHz/mm at the resonance order of m = 1. When the THz wave is at the near-zero loss frequency, both the loss and the dispersion of the guide modes are very low

Broadband THz transmission within the symmetrical plastic film coated parallel-plate waveguide

We report the broadband THz transmission within the symmetrical plastic film coated parallel-plate waveguide. We theoretically study the antiresonant reflecting mechanism of the waveguide and we find that the broadband THz wave can transmit in this waveguide with ultra-low loss. The loss of TM mode in this waveguide can be 4 orders of magnitude lower than the uncoated parallel-plate waveguide. The transmission bandwidth of this waveguide is up to 5.12 THz. We further show the mode field distributions which explain the loss mechanism