6,021 research outputs found

    Current status of metric reduction of (passive) scanner data

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    The extraction of metric information from scanner (particularly multispectral) data is presented. Data from both aircraft and spacecraft; singly scanned areas and areas with multiple coverage; various mathematical models used up to the present time; and published numerical results are considered. Future trends are also discussed

    Coherent transport in Josephson-Junction rhombi chain with quenched disorder

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    We consider a chain of Josephson-junction rhombi (proposed originally by Doucot and Vidal) in quantum regime. In a regular chain with no disorder in the maximally frustrated case when magnetic flux through each rhombi \Phi_r is equal to one half of superconductive flux quantum \Phi_0, Josephson current is due to correlated transport of pairs of Cooper pairs, i.e. charge is quantized in units of 4e4e. Sufficiently strong deviation \delta\Phi =|\Phi_r-\Phi_0/2| > \delta\Phi^c from the maximally frustrated point brings the system back to usual 2e2e-quantized supercurrent. For a regular chain \delta\Phi^c was calculated by us previously. Here we present detailed analysis of the effect of quenched disorder (random stray charges and random fluxes piercing rhombi) on the pairing effect.Comment: 21 pages, 5 figure

    Combining Full-Shape and BAO Analyses of Galaxy Power Spectra: A 1.6% CMB-independent constraint on H0

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    We present cosmological constraints from a joint analysis of the pre- and post-reconstruction galaxy power spectrum multipoles from the final data release of the Baryon Oscillation Spectroscopic Survey (BOSS). Geometric constraints are obtained from the positions of BAO peaks in reconstructed spectra, analyzed in combination with the unreconstructed spectra in a full-shape (FS) likelihood using a joint covariance matrix, giving stronger parameter constraints than FS-only or BAO-only analyses. We introduce a new method for obtaining constraints from reconstructed spectra based on a correlated theoretical error, which is shown to be simple, robust, and applicable to any flavor of density-field reconstruction. Assuming Λ\LambdaCDM with massive neutrinos, we analyze data from two redshift bins zeff=0.38,0.61z_\mathrm{eff}=0.38,0.61 and obtain 1.6%1.6\% constraints on the Hubble constant H0H_0, using only a single prior on the current baryon density ωb\omega_b from Big Bang Nucleosynthesis (BBN) and no knowledge of the power spectrum slope nsn_s. This gives H0=68.6±1.1 km s−1Mpc−1H_0 = 68.6\pm1.1\,\mathrm{km\,s}^{-1}\mathrm{Mpc}^{-1}, with the inclusion of BAO data sharpening the measurement by 40%40\%, representing one of the strongest current constraints on H0H_0 independent of cosmic microwave background data. Restricting to the best-fit slope nsn_s from Planck (but without additional priors on the spectral shape), we obtain a 1%1\% H0H_0 measurement of 67.8±0.7 km s−1Mpc−167.8\pm 0.7\,\mathrm{km\,s}^{-1}\mathrm{Mpc}^{-1}. We find strong constraints on the cosmological parameters from a joint analysis of the FS, BAO, and Planck data. This sets new bounds on the sum of neutrino masses ∑mν<0.14 eV\sum m_\nu < 0.14\,\mathrm{eV} (at 95%95\% confidence) and the effective number of relativistic degrees of freedom Neff=2.90−0.16+0.15N_\mathrm{eff} = 2.90^{+0.15}_{-0.16}, though contours are not appreciably narrowed by the inclusion of BAO data.Comment: 42 pages, 12 figures, accepted by JCAP, likelihoods available at https://github.com/Michalychforever/lss_montepython (minor typo corrected

    Gauge theory approach to glass transitions

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    This theory combines a thermodynamic approach with a dynamic one in order to describe glass transition. Glass transition is regarded as an inaccessible second order phase transition, which is interrupted because of premature critical slowing down, caused by the system's frustration. The frustration-induced vortices are present in the structure besides thermoactivated vortices, and prevent the development of the order parameter fluctuations, that leads to the critical slowing down the system kinetics at some temperature above the phase transition point

    On the extra phase correction to the semiclassical spin coherent-state propagator

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    The problem of an origin of the Solary-Kochetov extra-phase contribution to the naive semiclassical form of a generalized phase-space propagator is addressed with the special reference to the su(2) spin case which is the most important in applications. While the extra-phase correction to a flat phase-space propagator can straightforwardly be shown to appear as a difference between the principal and the Weyl symbols of a Hamiltonian in the next-to-leading order expansion in the semiclassical parameter, the same statement for the semiclassical spin coherent-state propagator holds provided the Holstein-Primakoff representation of the su(2) algebra generators is employed.Comment: 19 pages, no figures; a more general treatment is presented, some references are added, title is slightly changed; submitted to JM
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