119199675
Comments on the Monopole-Antimonopole Pair Solutions
Recently, the monopole-antimonopole pair and monopole-antimonopole chain solutions are solved with internal space coordinate system of -winding number m greater than one. However, we notice that it is also possible to solve these solutions numerically in terms of -winding number m = 1 instead. When m = 1, the exact asymptotic solutions at small and large distances are parameterized by a single integer parameter s. Here we once again study the monopole-antimonopole pair solution of the SU(2) YangMills-Higgs theory which belongs to the topological trivial sector numerically in its new form. This solution with -winding and -winding number one is parameterized by s = 0 at small r and s = 1 at large r.
121227608
Vortex Ring Dyons of the SU(2) Yang‐Mills‐Higgs Model
We present an axially symmetric vortex ring dyons solutions of the SU(2) Yang‐Mills‐Higgs theory. These vortex rings carry electric charges that are determined by a parameter, −1⩽η⩽1. They possess vanishing magnetic charge and are located at a ring centered around the z‐axis where the Higgs field vanishes. These stationary vortex ring dyon solutions possess finite energy but they do not satisfy the first order Bogomol’nyi equations. In the Bogomol’nyi‐Prasad‐Sommerfield (BPS) limit where the Higgs field potential is zero, the time component of the gauge field is parallel to the Higgs field in isospace. The total energy, net electric charge and diameter of the vortex ring increase exponentially to infinity when η approaches ±1. On the contrary, when λ = 1, all these three values reach their critical value as η approaches ±1.
119270486
Monopole–antimonopole pair dyons with critical electric charges
In this paper, we investigate some electrically charged magnetic solutions of the SU(2) Yang–Mills–Higgs field theory in the net-zero topological charge sector. We only examine the case when the Higgs field vanishes at two points along the z-axis and when the Higgs field vanishes along a ring with the z-axis as its symmetry axis. We study the possible electric charges the dyons can carry in relation to the electric–magnetic charge separations and calculate the finite total energy and magnet dipole moment of these dyons. These stationary dyon solutions do not satisfy the first-order Bogomol’nyi equations and are non-BPS solutions. They are axially symmetric saddle-point solutions and are characterized by the electric charge parameter, −1 < η < 1, which determines the net electric charges of these dyons. These dyon solutions are solved numerically when the magnetic charges are n = 1, 2, 3, 4 and 5, and when the strength of the Higgs field potential is non-vanishing with λ = 1. When λ = 1, we found that the net electric charge approaches a finite critical value as η approaches ±1. Hence the electromagnetic charge separation, total energy and magnetic dipole moment of the dyon also approach a finite critical value.
18053468
Half-monopole and multimonopole
We would like to present some exact SU(2) Yang–Mills–Higgs monopole solutions of half-integer topological charge. These solutions can be just an isolated half-monopole or a multimonopole with topological magnetic charge ½m where m is a natural number. These static monopole solutions satisfy the first order Bogomol'nyi equations. The axially symmetric one-half monopole gauge potentials possess a Dirac-like string singularity along the negative z-axis. The multimonopole gauge potentials are also singular along the z-axis and possess only mirror symmetries.
15789506
DYONS OF ONE-HALF MONOPOLE CHARGE
We would like to present some exact SU(2) Yang–Mills–Higgs dyon solutions of one-half monopole charge. These static dyon solutions satisfy the first order Bogomol'nyi equations and are characterized by a parameter, m. They are axially symmetric. The gauge potentials and the electromagnetic fields possess a string singularity along the negative z-axis and hence they possess infinite energy density along the line singularity. However the net electric charges of these dyons which varies with the parameter m are finite.
119217960
Inflating wormholes in the braneworld models
The braneworld model, in which our Universe is a three-brane embedded in a five-dimensional bulk, allows the existence of wormholes, without any violation of the energy conditions. A fundamental ingredient of traversable wormholes is the violation of the null energy condition (NEC). However, in the braneworld models, the stress–energy tensor confined on the brane, threading the wormhole, satisfies the NEC. In conventional general relativity, wormholes existing before inflation can be significantly enlarged by the expanding spacetime. We investigate the evolution of an inflating wormhole in the braneworld scenario, in which the wormhole is supported by the nonlocal braneworld effects. As a first step in our study, we consider the possibility of embedding a four-dimensional braneworld wormhole into a five-dimensional bulk. The conditions for the embedding are obtained by studying the junction conditions for the wormhole geometry, as well as the full set of the five-dimensional bulk field equations. For the description of the inflation, we adopt the chaotic inflation model. We study the dynamics of the braneworld wormholes during the exponential inflation stage, and in the stage of the oscillating scalar field. A particular exact solution corresponding to a zero redshift wormhole is also obtained. The resulting evolution shows that while the physical and geometrical parameters of a zero redshift wormhole decay naturally, a wormhole satisfying some very general initial conditions could turn into a black hole and exist forever.
118580751
Weyl fluid dark matter model tested on the galactic scale by weak gravitational lensing
The higher-dimensional Weyl curvature induces on the brane a new source of gravity. This Weyl fluid of geometrical origin (reducing in the spherically symmetric, static configuration to a dark radiation and dark pressure) modifies spacetime geometry around galaxies and has been shown to explain the flatness of galactic rotation curves. Independent observations for discerning between the Weyl fluid and other dark matter models are necessary. Gravitational lensing could provide such a test. Therefore we study null geodesics and weak gravitational lensing in the dark radiation dominated region of galaxies in a class of spherically symmetric braneworld metrics. We find that the lensing profile in the braneworld scenario is distinguishable from dark matter lensing, despite both the braneworld scenario and dark matter models fitting the rotation curve data. In particular, in the asymptotic regions, light deflection is 18% enhanced as compared to dark matter halo predictions. For a linear equation of state of the Weyl fluid, we further find a critical radius below which braneworld effects reduce, while above it they amplify light deflection. This is in contrast to any dark matter model, the addition of which always increases the deflection angle.
971110
Static potential and local color fields in unquenched three-dimensional lattice QCD
Abstract String breaking by dynamical quarks in (2+1)-d lattice QCD is demonstrated in this project, by measuring the static potential and the local color-electric field strength between a heavy quark and antiquark pair at large separations. Simulations are done for unquenched SU(2) color with two flavors of staggered quarks. An improved gluon action is used which allows simulations to be done on coarse lattices, providing an extremely efficient means to access the quark separations and propagation times at which string breaking occurs. The static quark potential is extracted using only Wilson loop operators and hence no valence quarks are present in the trial states. Results give unambiguous evidence for string breaking as the static quark potential completely saturates at twice the heavy-light meson mass at large separations. It is also shown that the local color-electric field strength between the quark pair tends toward vacuum values at large separations. Implications of these results for unquenched simulations of QCD in 4-d are drawn.
15254963
Lens Galaxy Properties of SBS 1520+530: Insights from Keck Spectroscopy and AO Imaging
We report on an investigation of the SBS 1520+530 gravitational lens system. We have used archival Hubble Space Telescope (HST) imaging, Keck spectroscopic data, and Keck adaptive optics (AO) imaging to study the lensing galaxy and its environment. The AO imaging has allowed us to fix the lens galaxy properties with a high degree of accuracy when performing the lens modeling, and the data indicate that the lens has an elliptical morphology and perhaps a disk. The new spectroscopic data suggest that previous determinations of the lens redshift may be incorrect, and we report an updated, although inconclusive, value z(lens) = 0.761. We have also spectroscopically confirmed the existence of several galaxy groups at approximately the redshift of the lens system. We create new models of the lens system that explicitly account for the environment of the lens, and we also include improved constraints on the lensing galaxy from our AO imaging. Lens models created with these new data can be well fit with a steeper than isothermal mass slope (α = 2.29, where ρ propto r−α) if H_0 is fixed at 72 km s^(-1) Mpc^(-1); isothermal models require H_0 similar to 50 km s^(-1) Mpc^(-1). The steepened profile may indicate that the lens is in a transient perturbed state caused by interactions with a nearby galaxy.
18491679
Galaxy Number Counts and Implications for Strong Lensing
We compare galaxy number counts in Advanced Camera for Surveys (ACS) fields containing moderate-redshift (0.2 <z <1.0) strong gravitational lenses with those in two control samples: (1) the first square degree of the COSMOS survey, comprising 259 ACS fields and (2) 20 ‘pure-parallel’ fields randomly located on the sky. Through a Bayesian analysis we determine the expectation values (μ0) and confidence levels of the underlying number counts for a range of apertures and magnitude bins. Our analysis has produced the following results: (i) we infer that our control samples are not consistent, with the number counts in the COSMOS sample being significantly higher than in the pure-parallel sample for 21 ≤F814W≤ 23. This result matches those found in previous analyses of COSMOS data using different techniques. (ii) We find that small-sized apertures, centred on strong lenses, are overdense compared with randomly placed apertures in the control samples, even compared to the COSMOS sample. Correcting for the local clustering of elliptical galaxies, based on the average two-point correlation function, reduces this overdensity to the 1-2σ level. Thus, the overdensity of galaxies seen along a typical line of sight to a lens can be explained mostly by the natural clustering of galaxies, rather than being due to lenses lying along otherwise biased lines of sight. However, a larger sample of lenses is needed to see if the remaining bias persists when the lens-field uncertainties are smaller. (iii) There is considerable scatter in the lines of sight to individual lens systems, but quantities that are linearly dependent on the external convergence (e.g. H0) should become unbiased if the extra galaxies that cause the bias can be accounted for in the lens models either through direct modelling or via an informed prior on the external convergence. The number counts can be used to set such an informed prior.