15,936 research outputs found

    Eigenstates of Paraparticle Creation Operators

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    Eigenstates of the parabose and parafermi creation operators are constructed. In the Dirac contour representation, the parabose eigenstates correspond to the dual vectors of the parabose coherent states. In order p=2p=2, conserved-charge parabose creation operator eigenstates are also constructed. The contour forms of the associated resolutions of unity are obtained.Comment: 14 pages, LaTex file, no macros, no figure

    Irreducible MultiQutrit Correlations in Greenberger-Horne-Zeilinger Type States

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    Following the idea of the continuity approach in [D. L. Zhou, Phys. Rev. Lett. 101, 180505 (2008)], we obtain the degrees of irreducible multi-party correlations in two families of nn-qutrit Greenberger-Horne-Zeilinger type states. For the pure states in one of the families, the irreducible 2-party, nn-party and (nm)(n-m)-party (0<m<n20< m < n-2) correlations are nonzero, which is different from the nn-qubit case. We also derive the correlation distributions in the nn-qutrit maximal slice state, which can be uniquely determined by its (n1)(n-1)-qutrit reduced density matrices among pure states. It is proved that there is no irreducible nn-qutrit correlation in the maximal slice state. This enlightens us to give a discussion about how to characterize the pure states with irreducible nn-party correlation in arbitrarily high-dimensional systems by the way of the continuity approach.Comment: 5p, no fi

    Photometric properties and luminosity function of nearby massive early-type galaxies

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    We perform photometric analyses for a bright early-type galaxy (ETG) sample with 2949 galaxies (Mr<22.5M_{\rm r}<-22.5 mag) in the redshift range of 0.05 to 0.15, drawn from the SDSS DR7 with morphological classification from Galaxy Zoo 1. We measure the Petrosian and isophotal magnitudes, as well as the corresponding half-light radius for each galaxy. We find that for brightest galaxies (Mr<23M_{\rm r}<-23 mag), our Petrosian magnitudes, and isophotal magnitudes to 25 mag/arcsec2{\rm mag/arcsec^2} and 1\% of the sky brightness are on average 0.16 mag, 0.20 mag, and 0.26 mag brighter than the SDSS Petrosian values, respectively. In the first case the underestimations are caused by overestimations in the sky background by the SDSS PHOTO algorithm, while the latter two are also due to deeper photometry. Similarly, the typical half-light radii (r50r_{50}) measured by the SDSS algorithm are smaller than our measurements. As a result, the bright-end of the rr-band luminosity function is found to decline more slowly than previous works. Our measured luminosity densities at the bright end are more than one order of magnitude higher than those of Blanton et al. (2003), and the stellar mass densities at M5×1011MM_{\ast}\sim 5\times10^{11} M_{\odot} and M1012MM_{\ast}\sim 10^{12} M_{\odot} are a few tenths and a factor of few higher than those of Bernardi et al. (2010). These results may significantly alleviate the tension in the assembly of massive galaxies between observations and predictions of the hierarchical structure formation model.Comment: 43 pages, 14 figures, version accepted for publication in the Astrophysical Journa

    Accurate determination of the Lagrangian bias for the dark matter halos

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    We use a new method, the cross power spectrum between the linear density field and the halo number density field, to measure the Lagrangian bias for dark matter halos. The method has several important advantages over the conventional correlation function analysis. By applying this method to a set of high-resolution simulations of 256^3 particles, we have accurately determined the Lagrangian bias, over 4 magnitudes in halo mass, for four scale-free models with the index n=-0.5, -1.0, -1.5 and -2.0 and three typical CDM models. Our result for massive halos with MMM \ge M_* (MM_* is a characteristic non-linear mass) is in very good agreement with the analytical formula of Mo & White for the Lagrangian bias, but the analytical formula significantly underestimates the Lagrangian clustering for the less massive halos $M < M_*. Our simulation result however can be satisfactorily described, with an accuracy better than 15%, by the fitting formula of Jing for Eulerian bias under the assumption that the Lagrangian clustering and the Eulerian clustering are related with a linear mapping. It implies that it is the failure of the Press-Schechter theories for describing the formation of small halos that leads to the inaccuracy of the Mo & White formula for the Eulerian bias. The non-linear mapping between the Lagrangian clustering and the Eulerian clustering, which was speculated as another possible cause for the inaccuracy of the Mo & White formula, must at most have a second-order effect. Our result indicates that the halo formation model adopted by the Press-Schechter theories must be improved.Comment: Minor changes; accepted for publication in ApJ (Letters) ; 11 pages with 2 figures include

    Is the Number of Giant Arcs in LCDM Consistent With Observations?

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    We use high-resolution N-body simulations to study the galaxy-cluster cross-sections and the abundance of giant arcs in the Λ\LambdaCDM model. Clusters are selected from the simulations using the friends-of-friends method, and their cross-sections for forming giant arcs are analyzed. The background sources are assumed to follow a uniform ellipticity distribution from 0 to 0.5 and to have an area identical to a circular source with diameter 1\arcsec. We find that the optical depth scales as the source redshift approximately as \tau_{1''} = 2.25 \times 10^{-6}/[1+(\zs/3.14)^{-3.42}] (0.6<\zs<7). The amplitude is about 50% higher for an effective source diameter of 0.5\arcsec. The optimal lens redshift for giant arcs with the length-to-width ratio (L/WL/W) larger than 10 increases from 0.3 for \zs=1, to 0.5 for \zs=2, and to 0.7-0.8 for \zs>3. The optical depth is sensitive to the source redshift, in qualitative agreement with Wambsganss et al. (2004). However, our overall optical depth appears to be only \sim 10% to 70% of those from previous studies. The differences can be mostly explained by different power spectrum normalizations (σ8\sigma_8) used and different ways of determining the L/WL/W ratio. Finite source size and ellipticity have modest effects on the optical depth. We also found that the number of highly magnified (with magnification μ>10|\mu|>10) and ``undistorted'' images (with L/W<3L/W<3) is comparable to the number of giant arcs with μ>10|\mu|>10 and L/W>10L/W>10. We conclude that our predicted rate of giant arcs may be lower than the observed rate, although the precise `discrepancy' is still unclear due to uncertainties both in theory and observations.Comment: Revised version after the referee's reports (32 pages,13figures). The paper has been significantly revised with many additions. The new version includes more detailed comparisons with previous studies, including the effects of source size and ellipticity. New discussions about the redshift distribution of lensing clusters and the width of giant arcs have been adde

    Hidden nonlinear supersymmetries in pure parabosonic systems

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    The existence of intimate relation between generalized statistics and supersymmetry is established by observation of hidden supersymmetric structure in pure parabosonic systems. This structure is characterized generally by a nonlinear superalgebra. The nonlinear supersymmetry of parabosonic systems may be realized, in turn, by modifying appropriately the usual supersymmetric quantum mechanics. The relation of nonlinear parabosonic supersymmetry to the Calogero-like models with exchange interaction and to the spin chain models with inverse-square interaction is pointed out.Comment: 20 pages, one reference corrected, to appear in Int. J. Mod. Phys.

    The Power Spectrum, Bias Evolution, and the Spatial Three-Point Correlation Function

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    We calculate perturbatively the normalized spatial skewness, S3S_3, and full three-point correlation function (3PCF), ζ\zeta, induced by gravitational instability of Gaussian primordial fluctuations for a biased tracer-mass distribution in flat and open cold-dark-matter (CDM) models. We take into account the dependence on the shape and evolution of the CDM power spectrum, and allow the bias to be nonlinear and/or evolving in time, using an extension of Fry's (1996) bias-evolution model. We derive a scale-dependent, leading-order correction to the standard perturbative expression for S3S_3 in the case of nonlinear biasing, as defined for the unsmoothed galaxy and dark-matter fields, and find that this correction becomes large when probing positive effective power-spectrum indices. This term implies that the inferred nonlinear-bias parameter, as usually defined in terms of the smoothed density fields, might depend on the chosen smoothing scale. In general, we find that the dependence of S3S_3 on the biasing scheme can substantially outweigh that on the adopted cosmology. We demonstrate that the normalized 3PCF, QQ, is an ill-behaved quantity, and instead investigate QVQ_V, the variance-normalized 3PCF. The configuration dependence of QVQ_V shows similarly strong sensitivities to the bias scheme as S3S_3, but also exhibits significant dependence on the form of the CDM power spectrum. Though the degeneracy of S3S_3 with respect to the cosmological parameters and constant linear- and nonlinear-bias parameters can be broken by the full configuration dependence of QVQ_V, neither statistic can distinguish well between evolving and non-evolving bias scenarios. We show that this can be resolved, in principle, by considering the redshift dependence of ζ\zeta.Comment: 41 pages, including 12 Figures. To appear in The Astrophysical Journal, Vol. 521, #
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