119277808
Knot topology in QCD
Abstract We consider topological structure of classical vacuum solutions in quantum chromodynamics. Topologically non-equivalent vacuum configurations are classified by non-trivial second and third homotopy groups for coset of the color group SU ( N ) ( N = 2 , 3 ) under the action of maximal Abelian stability group. Starting with explicit vacuum knot configurations we study possible exact classical solutions. Exact analytic non-static knot solution in a simple CP 1 model in Euclidean space–time has been obtained. We construct an ansatz based on knot and monopole topological vacuum structure for searching new solutions in SU ( 2 ) and SU ( 3 ) QCD. We show that singular knot-like solutions in QCD in Minkowski space–time can be naturally obtained from knot solitons in integrable CP 1 models. A family of Skyrme type low energy effective theories of QCD admitting exact analytic solutions with non-vanishing Hopf charge is proposed.
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.
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.
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.
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.
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.
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.
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.
31711511
Probing gravity at cosmological scales by measurements which test the relationship between gravitational lensing and matter overdensity.
The standard cosmology is based on general relativity (GR) and includes dark matter and dark energy and predicts a fixed relationship between the gravitational potentials responsible for gravitational lensing and the matter overdensity. Alternative theories of gravity often make different predictions. We propose a set of measurements which can test this relationship, thereby distinguishing between dark energy or matter models and models in which gravity differs from GR. Planned surveys will be able to measure E(G), an observational quantity whose expectation value is equal to the ratio of the Laplacian of the Newtonian potentials to the peculiar velocity divergence, to percent accuracy. This will easily separate alternatives such as the cold dark matter model with a cosmological constant, Dvali-Gabadadze-Porrati, TeVeS, and f(R) gravity.
44301996
BEAM-BASED HOM STUDY IN THIRD HARMONIC SC CAVITIES FOR BEAM ALIGNMENT AT FLASH*
An electron beam entering an accelerator cavity excites higher order modes (HOM). These are radiated to HOM couplers and subsequently damped. They can also be used to facilitate beam position monitoring. The modes excited by off-axis beams are the focus of this study. Results are presented on the first analysis of HOM dependency on the beam position for the third harmonic cavities at FLASH. The analysis is based on the beampipe and cavity dipole modes. Various analysis methods are used and compared to satisfy the needs emerging from the characteristics of those modes. The electric center of each mode is observed by looking for the minima of the HOM signals of different beam positions. A single electron bunch per RF pulse is used.
119275711
Exact analytical solution of the linear structure growth rate in Lambda CDM cosmology and its cosmological applications
We derive the exact analytical solution of the linear structure growth rate in {Lambda}CDM cosmology with flat or curved geometry, under the Newtonian gauge. Unlike the well known solution under the Newtonian limit [D. J. Heath, Mon. Not. R. Astron. Soc. 179, 351 (1977)], our solution takes all general relativistic corrections into account and is hence valid at both the sub- and superhorizon scales. With this exact solution, we evaluate cosmological impacts induced by these relativistic corrections. (1) General relativistic corrections alter the density growth from z=100 to z=0 by 10% at k=0.01 h/Mpc and the impact becomes stronger toward larger scales. We caution the readers that the overdensity is not gauge invariant and the above statement is restrained to the Newtonian gauge. (2) Relativistic corrections introduce a k{sup -2} scale dependence in the density fluctuation. It mimics a primordial non-Gaussianity of the local type with f{sub NL}{sup local{approx}}1. This systematical error may become non-negligible for future all sky deep galaxy surveys. (3) Cosmological simulations with box size greater than 1 Gpc are also affected by these relativistic corrections. We provide a postprocessing recipe to correct for these effects. (4) These relativistic corrections affect the redshift distortion. However, at redshiftsmore » and scales relevant to redshift distortion measurements, such effect is negligible.« less