16157496
Universal amplitude ratios of the renormalization group: two-dimensional tricritical Ising model.
The scaling form of the free energy near a critical point allows for the definition of various thermodynamical amplitudes and the determination of their dependence on the microscopic nonuniversal scales. Universal quantities can be obtained by considering special combinations of the amplitudes. Together with the critical exponents they characterize the universality classes and may be useful quantities for their experimental identification. We compute the universal amplitude ratios for the tricritical Ising model in two dimensions by using several theoretical methods from perturbed conformal field theory and scattering integrable quantum field theory. The theoretical approaches are further supported and integrated by results coming from a numerical determination of the energy eigenvalues and eigenvectors of off-critical systems in an infinite cylinder.
15453015
Interplay between classical magnetic moments and superconductivity in quantum one-dimensional conductors: toward a self-sustained topological Majorana phase.
We study a one-dimensional interacting electronic liquid coupled to a 1D array of classical magnetic moments and to a superconductor. We show that at low energy and temperature the magnetic moments and the electrons become strongly entangled and that a magnetic spiral structure emerges. For strong enough coupling between the electrons and magnetic moments, the 1D electronic liquid is driven into a topological superconducting phase supporting Majorana fermions without any fine-tuning of external parameters. Our analysis applies at low enough temperature to a quantum wire in proximity to a superconductor when the hyperfine interaction between electrons and nuclear spins is taken into account, or to a chain of magnetic adatoms adsorbed on a superconducting surface.
14198652
Bosonic-type S -matrix, vacuum instability and CDD ambiguities
Abstract We consider the simplest bosonic-type S -matrix which is usually regarded as unphysical due to the complex values of the finite volume ground state energy. While a standard quantum field theory interpretation of such a scattering theory is precluded, we argue that the physical situation described by this S -matrix is of a massive Ising model perturbed by a particular set of irrelevant operators. The presence of these operators drastically affects the stability of the original vacuum of the massive Ising model and its ultraviolet properties.
124148859
2-D fractional supersymmetry: From rational to irrational conformal field theory
119377774
2D FRACTIONAL SUPERSYMMETRY FOR RATIONAL CONFORMAL FIELD THEORY : APPLICATION FOR THIRD-INTEGER SPIN STATES
A 2D fractional supersymmetry theory is algebraically constructed. The Lagrangian is derived using an adapted superspace including, in addition to a scalar field, two fields with spins 13, 23 This theory turns out to be a rational conformal field theory. The symmetry of this model goes beyond the super-Virasoro algebra and connects these third-integer spin states. Besides the stress-momentum tensor, we obtain a supercurrent of spin 43. Cubic relations are involved in order to close the algebra; the basic algebra is no longer a Lie or a super-Lie algebra. The central charge of this model is found to be 53 Finally, we analyze the form that a local invariant action should take.
119500460
Coupled critical models: application to Ising-Potts models
Abstract We discuss the critical behaviour of 2 D Ising and q -states Potts models coupled by their energy density. We found new tricritical points. The procedure employed is the renormalisation approach of the perturbations series around conformal field theories representing pure models as already used for disordered spins models. This analysis could be useful to understand the physics of coupled critical models like the fully frustrated XY model.
17068714
Signatures in a Giant Radio Galaxy of a Cosmological Shock Wave at Intersecting Filaments of Galaxies
Sensitive images of low-level, megaparsec-sized radio cocoons offer new opportunities to probe large-scale intergalactic gas flows outside clusters of galaxies. New radio images of high surface brightness sensitivity at strategically chosen wavelengths of the giant radio galaxy NGC 315 reveal significant asymmetries and particularities in the morphology, radio spectrum, and polarization of the ejected radio plasma. We argue that the combination of these signatures provides a sensitive probe of an environmental shock wave. Analysis of optical redshifts in NGC 315's vicinity confirms its location to be near, or at, a site of large-scale flow collisions in the 100 Mpc sized Pisces-Perseus supercluster region. NGC 315 resides at the intersection of several galaxy filaments, and its radio plasma serves there as a "weather station," probing the flow of the elusive and previously invisible intergalactic medium gas. If our interpretation is correct, this is the first indication for a shock wave in flows caused by the cosmological large-scale structure formation, which is located in a filament of galaxies. The possibility that the putative shock wave is a source of gamma rays and ultrahigh-energy cosmic rays is briefly discussed.
14997297
GaBoDS: the Garching-Bonn Deep Survey - III. Lyman-break galaxies in the Chandra Deep Field South
We present first results of our search for high-redshift galaxies in deep CCD mosaic images. As a pilot study for a larger survey, very deep images of the Chandra Deep Field South (CDFS), taken with WFI@MPG/ESO2.2m, are used to select large samples of 1070 U-band and 565 B-band dropouts with the Lyman-break method. The data of these Lyman-break galaxies are made public as an electronic table. These objects are good candidates for galaxies at z ∼ 3a ndz ∼ 4 which is supported by their photometric redshifts. The distributions of apparent magnitudes and the clustering properties of the two populations are analysed, and they show good agreement to earlier studies. We see no evolution in the comoving clustering scale length from z ∼ 3t oz ∼ 4. The techniques presented here will be applied to a much larger sample of U-dropouts from the whole survey in near future.
17142858
GaBoDS: The Garching-Bonn Deep Survey: VI. Cosmic shear analysis
Aims. We present a cosmic shear analysis and data validation of 15 square degree high-quality R-band data of the Garching-Bonn Deep Survey obtained with the Wide Field Imager of the MPG/ESO 2.2m telescope. Methods. We measure the two-point shear correlation functions to calculate the aperture mass dispersion. Both statistics are used to perform the data quality control. Combining the cosmic shear signal with a photometric redshift distribution of a galaxy sub-sample obtained from two square degree of UBVRI-band observations of the Deep Public Survey we determine constraints for the matter density Omega_m, the mass power spectrum normalisation sigma_8 and the dark energy density Omega_Lambda in the magnitude interval R in [21.5,24.5]. In this magnitude interval the effective number density of source galaxies is n=12.5/sq. arcmin, and their mean redshift is z_m=0.78. To estimate the posterior likelihood we employ the Monte Carlo Markov Chain method. Results. Using the aperture mass dispersion we obtain for the mass power spectrum normalisation sigma_8=0.80 +- 0.10 (1 sigma statistical error) at a fixed matter density Omega_m=0.30 assuming a flat universe with negligible baryon content and marginalising over the Hubble parameter and the uncertainties in the fitted redshift distribution.
119100161
CFHTLenS: the Canada-France-Hawaii Telescope Lensing Survey - imaging data and catalogue products
We present data products from the Canada–France–Hawaii Telescope Lensing Survey (CFHTLenS). CFHTLenS is based on the Wide component of the Canada–France–Hawaii Telescope Legacy Survey (CFHTLS). It encompasses 154 deg^2 of deep, optical, high-quality, sub-arcsecond imaging data in the five optical filters u*g′r′i′z′. The scientific aims of the CFHTLenS team are weak gravitational lensing studies supported by photometric redshift estimates for the galaxies. This paper presents our data processing of the complete CFHTLenS data set. We were able to obtain a data set with very good image quality and high-quality astrometric and photometric calibration. Our external astrometric accuracy is between 60 and 70 mas with respect to Sloan Digital Sky Survey (SDSS) data, and the internal alignment in all filters is around 30 mas. Our average photometric calibration shows a dispersion of the order of 0.01–0.03 mag for g′r′i′z′ and about 0.04 mag for u* with respect to SDSS sources down to i_(SDSS) ≤ 21. We demonstrate in accompanying papers that our data meet necessary requirements to fully exploit the survey for weak gravitational lensing analyses in connection with photometric redshift studies. In the spirit of the CFHTLS, all our data products are released to the astronomical community via the Canadian Astronomy Data Centre at http://www.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/community/CFHTLens/query.html. We give a description and how-to manuals of the public products which include image pixel data, source catalogues with photometric redshift estimates and all relevant quantities to perform weak lensing studies.
15490282
The galaxy-dark matter bias in the Garching-Bonn Deep Survey
We measured the bias and correlation factor of galaxies with respect to the dark matter using the aperture statistics including the aperture mass from weak gravitational lensing. The analysis was performed for three galaxy samples selected by R-band magnitudes; the median redshifts of the samples were $\ave{z}=0.34,0.49$ and 0.65, respectively. The brightest sample has the strongest peak in redshift and can therefore be most accurately represented by a single redshift. The data used is the GaBoDS, and the COMBO-17 survey for an accurate estimate of the redshift distribution of the galaxies. Assuming the currently favoured $\Lambda\rm CDM$ model as cosmology, we obtained values for the linear stochastic galaxy-dark matter bias on angular scales $1^\prime\le\theta\le20^\prime$. Averaging the measurements for the bias over the range $4^\prime\le \theta_{\rm ap}\le 18^\prime$, weighting with the cosmic variance error, yields $b=0.89(5), 0.79(5), 0.89(5)$, respectively ($1\sigma$). As for the correlation factor $r$ we see, as Hoekstra et al. (2002), a slight increase to $r=1$ in the last angular bin from an almost constant value on smaller scales; the weighted average here over the same range as before is $r=0.8(1), 0.8(1), 0.5(1)$, respectively (abridged).