119294901
E8(8) in Light Cone Superspace
We derive the non-linear action of E-8(8) on the constrained chiral superfield in the light-cone superspace with eight complex Grassmann variables. We construct (to lowest order in the coupling) the sixteen dynamical supersymmetries which generate a Hamiltonian with E-8(8) invariance in three space-time dimensions, and show that it has only interactions with even powers of the coupling constant.
16094871
Non-linear realization of PSU(2,2|4) on the light-cone
The symmetries of the N=4 SuperYang-Mills theory on the light-cone are discussed, solely in terms of its physical degrees of freedom. We derive explicit expressions for the generators of the PSU(2,2|4) superalgebra, both in the free theory, and to all orders in the gauge coupling of the classical theory. We use these symmetries to construct its Hamiltonian, and show that it can be written as a quadratic form of a fermionic superfield.
18632800
Soliton and Domain Wall in the Self-Dual Ferromagnet
We perform the dimensional reduction of a uniaxial planar ferromagnet system coupled to an Abelian Chern-Simons gauge field in the self-dual limit, and investigate the soliton and domain wall solutions of the emerging 1+1 dimensional self-dual system. This self-dual ferromagnet is the usual inhomogeneous Landau-Lifshitz system with an extra non-local term supplementing the anisotropic potential energy. The Hamiltonian is Bogomol’nyi bounded from below and has four adjusting parameters. The Bogomol’nyi equation is described in detail in analogy with the Newtonian equation of motion and its numerical solution is presented. PACS codes: 11.10.Lm, 11.27.+d
118247985
N=5 three-algebras and 5-graded Lie superalgebras
We discuss a generalization of N=6 three-algebras to N=5 three-algebras in connection to anti-Lie triple systems and basic Lie superalgebras of type II. We then show that the structure constants defined in anti-Lie triple systems agree with those of N=5 superconformal theories in three dimensions.
118368147
Counterterms in gravity in the light-front formulation and a D = 2 conformal-like symmetry in gravity
A bstractIn this paper we discuss gravity in the light-front formulation (light-cone gauge) and show how possible counterterms arise. We find that Poincaré invariance is not enough to find the three-point counterterms uniquely. Higher-spin fields can intrude and mimic three-point higher derivative gravity terms. To select the correct term we have to use the remaining reparametrization invariance that exists after the gauge choice. We finally sketch how the corresponding programme for N = 8 Supergravity should work.
120898350
Surplus Solid Angle in Horava-Lifshitz Gravity
We consider Hořava-Lifshitz gravity coupled to the electrostatic field of a point charge, and show that the static solutions describe a space with a surplus (or deficit) solid angle. Unlike in general relativity, appearance of a surplus angle seems generic in Hořava-Lifshitz gravity. We discuss possible astrophysical effects due to a surplus angle.
16833191
Hubble Space Telescope/NICMOS Observations of Massive Stellar Clusters near the Galactic Center
We report Hubble Space Telescope (HST) Near-Infrared Camera and Multiobject Spectrometer (NICMOS) observations of the Arches and Quintuplet clusters, two extraordinary young clusters near the Galactic center. For the first time, we have identified main-sequence stars in the Galactic center with initial masses well below 10 M?. We present the first determination of the initial mass function (IMF) for any population in the Galactic center, finding an IMF slope that is significantly more positive (? ? -0.65) than the average for young clusters elsewhere in the Galaxy (? ? -1.4). The apparent turnoffs in the color-magnitude diagrams suggest cluster ages that are consistent with the ages implied by the mixture of spectral types in the clusters; we find ?age ~ 2 ? 1 Myr for the Arches cluster and ?age ~ 4 ? 1 Myr for the Quintuplet. We estimate total cluster masses by adding the masses of observed stars down to the 50% completeness limit and then extrapolating down to a lower mass cutoff of 1 M?. Using this method, we find 104 M? for the total mass of the Arches cluster. Such a determination for the Quintuplet cluster is complicated by the double-valued mass-magnitude relationship for clusters with ages 3?Myr. We find a lower limit of 6300 M? for the total cluster mass and suggest a best estimate of twice this value, which accounts for the outlying members of the cluster. Both clusters have masses that place them as the two most massive young clusters in the Galaxy.
18183448
Two-Component Fokker-Planck Models for the Evolution of Isolated Globular Clusters
Two-component (normal and degenerate stars) models are the simplest realization of clusters with a mass spectrum because high-mass stars evolve quickly into degenerates, while low-mass stars remain on the main sequence for the age of the universe. Here we examine the evolution of isolated globular clusters by using two-component Fokker-Planck (FP) models that include heating by binaries formed in tidal capture and in three-body encounters. Three-body binary heating dominates, and the postcollapse expansion is self-similar, at least in models with total mass M ≤ 3 × 105 M☉, initial half-mass radius rh,i ≥ 5 pc, component mass ratio m2/m1 ≥ 2, and number ratio N1/N2 ≤ 300, when m2 = 1.4 M☉. We derive scaling laws for ρc, vi, rc, and rh as functions of m1/m2, N, M, and time t from simple energy-balance arguments; these agree well with the FP simulations. We have studied the conditions under which gravothermal oscillations (GTOs) occur. If Etot and Ec are the energies of the cluster and of the core, respectively, and trh and tc are their relaxation times, then ≡ (Etot/trh)/(Ec/trc) is a good predictor of GTOs: all models with > 0.01 are stable, and all but one with < 0.01 oscillate. We derive a scaling law for against N and m1/m2 and compare them with our numerical results. Clusters with larger m2/m1 or smaller N are stabler.
18940226
GALACTIC WARPS IN TRIAXIAL HALOS
We study the behavior of galactic disks in triaxial halos both numerically and analytically to see if warps can be excited and sustained in triaxial potentials. We consider the following two scenarios: (1) galactic disks that are initially tilted relative to the equatorial plane of the halo (for a pedagogical purpose), and (2) tilted infall of dark matter relative to the equatorial plane of the disk and the halo. With numerical simulations of 100,000 disk particles in a fixed halo potential, we find that in triaxial halos, warps can be excited and sustained just as in spherical or axisymmetric halos but they show some oscillatory behavior and even can be transformed to a polar-ring system if the halo has a prolate-like triaxiality. The nonaxisymmetric component of the halo causes the disk to nutate, and the differential nutation between the inner and outer parts of the disk generally makes the magnitude of the warp slightly diminish and fluctuate. We also find that warps are relatively weaker in oblate and oblate-like triaxial halos, and since these halos are the halo configurations of disk galaxies inferred by cosmological simulations, our results are consistent with the fact that most of the observed warps are quite weak. We derive approximate formulae for the torques exerted on the disk by the triaxial halo and the dark matter torus, and with these formulae we successfully describe the behavior of the disks in our simulations. The techniques used in deriving these formulae could be applied for realistic halos with more complex structures.
118275742
Supersymmetry non-renormalization theorem from a computer and the AdS/CFT correspondence
We perform Monte Carlo calculation of correlation functions in 4d N=4 super Yang-Mills theory on R*S^3 in the planar limit. In order to circumvent the well-known problem of lattice SUSY, we adopt the idea of a novel large-N reduction, which reduces the calculation to that of corresponding correlation functions in the plane-wave matrix model or the BMN matrix model. This model is a 1d gauge theory with 16 supersymmetries, which can be simulated in a manner similar to the recent studies of the D0-brane system. We study two-point and three-point functions of chiral primary operators at various coupling constant, and find that they agree with the free theory results up to overall constant factors. The ratio of the overall factors for two-point and three-point functions agrees with the prediction of the AdS/CFT correspondence.
118625794
A SECOND-ORDER BIAS MODEL FOR THE LOGARITHMIC HALO MASS DENSITY
We present an analytic model for the local bias of dark matter halos in a ?CDM universe. The model uses the halo mass density instead of the halo number density and is searched for various halo mass cuts, smoothing lengths, and redshift epochs. We find that, when the logarithmic density is used, the second-order polynomial can fit the numerical relation between the halo mass distribution and the underlying matter distribution extremely well. In this model, the logarithm of the dark matter density is expanded in terms of log halo mass density to the second order. The model remains excellent for all halo mass cuts (from M cut = 3 ? 1011 to 3 ? 1012 h ?1 M ?), smoothing scales (from R = 5 h ?1?Mpc to 50 h ?1?Mpc), and redshift ranges (from z = 0 to 1.0) considered in this study. The stochastic term in the relation is found to be not entirely random, but a part of the term can be determined by the magnitude of the shear tensor.