6475881
Energy-Momentum of a Cosmological Brane Model and the Gauge Hierarchy
We analyze in this paper the general covariant energy-momentum tensor of the gravitational system in general five-dimensional cosmological brane-world models. Then through calculating this energy-momentum for the cosmological generalization of the Randall-Sundrum model, which includes the original RS model as the static limit, we are able to show that the weakness of the gravitation on the “visible” brane is a general feature of this model. This is the origin of the gauge hierarchy from a gravitational point of view. Our results are also consistent with the fact that a gravitational system has vanishing total energy.
118464609
The Equation of State for Scalar-Tensor Gravity
We show that the field equation of Brans-Dicke gravity and scalar-tensor gravity can be derived as the equation of state of Rindler spacetime, where the local thermodynamic equilibrium is maintained. Our derivation implies that the effective energy cannot feel the heat flow across the Rindler horizon.
120706090
DECOMPOSITION OF THE SEMI-SIMPLE GROUP CONNECTION AND COSMIC STRINGS IN THE LORENTZ SPACETIME
In a previous paper, we addressed the method of Abelian decomposition to the case of SU(N) Yang–Mills theory. Here, we extend the decomposition method further to the general case. With the Cartan–Weyl basis we decompose semisimple group connection and discuss the SO(3,1) group in particular. In terms of the vierbein projection, we propose two two-forms as the U(1) gauge fields in the SO(3,1) gauge theory and show that these two-forms are just the different cosmic string tensors. Meanwhile, these two-forms indicate that the cosmic strings appear naturally in the Lorentz spacetime, i.e. the torsion in the Riemann–Cartan spacetime is not necessary for the cosmic strings.
9177547
TOPOLOGICAL STRUCTURE OF THE MANY VORTICES SOLUTION IN JACKIW–PI MODEL
By using the gauge potential decomposition, we discuss the self-dual equation and its solution in Jackiw–Pi model. We obtain a new concrete self-dual equation and find relationship between Chern–Simons vortices solution and topological number which is determined by Hopf indices and Brouwer degrees of Ψ-mapping. To show the meaning of topological number we give several figures with different topological numbers. In order to investigate the topological properties of many vortices, we use five parameters (two positions, one scale, one phase per vortex and one charge of each vortex) to describe each vortex in many vortices solutions in Jackiw–Pi model. For many vortices, we give three figures with different topological numbers to show the effect of the charge on the many vortices solutions. We also study the quantization of flux of those vortices related to the topological numbers in this case.
122164804
Four-Dimensional Newton’s Constant in Brane World with a Sloping Extra Dimension
We show the four-dimensional Newton’s constant obtained naturally from five-dimensional brane world with a tinily sloping extra dimension, which is independent of the bulk Weyl tensor. The corresponding universe is stiff fluid dominated when the slope of extra dimension is very small. Otherwise, the universe may be undergoing a self-acceleration at present epoch and have a decelerated phase in very recent past.
121146051
The single vortex in the FFLO state
In this Letter, we study the generalized Ginzburg-Landau (GL) functional near the tricritical temperature, and obtain the vortex solution of the FFLO state. Furthermore, we investigate the structure of the vortex and find that the vortices shrink when the Zeeman effect is weaken or temperature is lowered. (C) 2010 Elsevier B.V. All rights reserved.
56073920
A Study of Beam Alignment Based on Coupling Modes in Third Harmonic Superconducting Cavities at FLASH
This paper presents a study of beam alignment in accelerating cavities based on beam-excited higher order modes (HOM). Among the transverse HOMs, dipole modes have the dominant contribution, and may have an adverse effect on the beam quality. Since they depend linearly on the transverse beam offset, their effect can be reduced by aligning the beam in the cavity. The study has been made on the four third harmonic superconducting cavities installed in the ACC39 module at FLASH. Modes with strong beam coupling were monitored while moving the beam and searching for the minimum excited HOM power.
118557906
Type Ia supernovae as speed sensors at intermediate redshifts
Large scale peculiar velocity (LSPV) is a crucial probe of dark matter, dark energy, and gravity at cosmological scales. However, its application is severely limited by measurement obstacles. We show that fluctuations in type Ia supernovae fluxes induced by LSPV offer a promising approach to measure LSPV at intermediate redshifts. In the 3D Fourier space, gravitational lensing, the dominant systematical error, is well suppressed, localized, and can be further corrected effectively. Advances in supernova observations can further significantly reduce shot noise induced by supernova intrinsic fluctuations, which is the dominant statistical error. Robust mapping on the motion of the dark universe through type Ia supernovae is thus feasible to z similar to 0.5.
16733931
Cross correlations of the cosmic infrared background
The cosmic infrared background (CIB) is a sensitive measure of the star formation history. But this background is overwhelmed by foregrounds, which bias the CIB mean flux and auto correlation measurement severely. Since dominant foregrounds do not correlate with the large scale structure, the cross correlation of CIB with galaxies is free of such foregrounds and presents as an unbiased measure of the star formation history. This also allows the measurement of CIB based on integrated intensity, whose theoretical prediction is based on energy conservation, thus is fairly model independent and robust. The redshift information of CIB sources can be directly recovered with the aid of galaxy photometric redshifts. In the far IR region, correlation signal is around 10% at degree scale. Combining FIRAS and SDSS, the cross correlation can be measured with 20% accuracy (statistical and systematics errors) at $l\sim 40$. Such measurement would allow the measurement of star formation rate with comparable accuracies to $z\sim 1$. Future CIB experiments with $1^{\circ}$ resolution are able to measure the star formation rate with 10% accuracy to $z\sim 1.5$. Secondary CMB anisotropies arising from the large scale structure correlate with CIB. The correlation strength is about $0.5\mu$K at $\sim 10^{\circ}$ (the integrated Sachs-Wolfe effect) and $\sim -0.3\mu$K at $\sim 1^{\circ}$ (the Sunyaev Zeldovich effect, Rayleigh-Jeans regime). FIRAS+WMAP would allow the measurement of the ISW effect with $\ga 5\sigma$ confidence. Its detection helps to constrain the amount of dark energy and far IR emissivity bias.
16130045
Isolating the Decay Rate of Cosmological Gravitational Potential
The decay rate of cosmological gravitational potential measures the deviation from Einstein-de Sitter universe and can put strong constraints on the nature of dark energy and gravity. The usual method to measure this decay rate is through the integrated Sachs-Wolfe (ISW) effect-large-scale structure (LSS) cross-correlation. However, the interpretation of the measured correlation signal is complicated by galaxy bias and the matter power spectrum. This could bias and/or degrade its constraints on the nature of dark energy and gravity. But combining the lensing-LSS cross-correlation measurements, the decay rate of gravitational potential can be isolated. For any given narrow redshift bin of LSS, the ratio of the two cross-correlations directly measures H(z)/W(χ, χs), where D is the linear growth factor of the gravitational potential, H is the Hubble constant at redshift z, W(χ, χs) is the lensing kernel, and χ and χs are the comoving angular diameter distance to lens and source, respectively. This method is optimal in the sense that (1) the measured quantity is essentially free of systematic errors and is only limited by cosmic variance, and (2) the measured quantity depends only on several cosmological parameters and can be predicted from first principles unambiguously. Although fundamentally limited by the inevitably large cosmic variance associated with the ISW measurements, it can still put useful independent constraints on the amount of dark energy and its equation of state. It can also provide a powerful test of modified gravity and can distinguish the Dvali-Gabadadze-Porrati model from ΛCDM at >2.5 σ confidence level.
14253775
SELF CALIBRATION OF GALAXY BIAS IN SPECTROSCOPIC REDSHIFT SURVEYS OF BARYON ACOUSTIC OSCILLATIONS
Baryon acousticoscillation (BAO)isapowerfulprobeon theexpansion oftheuniverse,sheddinglight on elusive dark energy and gravity atcosm ologicalscales. BAO m easurem entsthrough biased trac- ersofthe underlying m atterdensityeld,asm ostproposalsdo,can reach high statisticalaccuracy. However,possible scale dependence in biasm ay induce non-negligiblesystem aticalerrors,especially forthem ostam bitiousspectroscopicsurveysproposed.W eshow thatprecision spectroscopicredshift inform ation availablein thesesurveysallowsfor selfcalibration ofthegalaxybiasand itsstochasticity, as function ofscale and redshift. Through the eect ofredshift distortion,one can sim ultaneously m easure the realspace powerspectra ofgalaxies,galaxy-velocity and velocity,respectively. Atrel- evantscalesofBAO,galaxy velocity faithfully tracesthatofthe underlying m atter. This valuable feature enablesa ratherm odelindependentway to m easure the galaxy biasand itsstochasticity by com paring the three power spectra. For the square kilom eter array (SKA),this selfcalibration is statistically accurateto correctfor1% levelshiftin BAO peak positionsinduced by biasscaledepen- dence.Furtherm ore,wend thatSKA isabletodetectBAO in thevelocity powerspectrum ,opening a new window forBAO cosm ology. Subjectheadings: cosm ology:distancescale{large-scalestructureofuniverse{theory 1. IN TRO D U CTIO N