13,250 research outputs found

    Phase structure of Abelian Chern-Simons gauge theories

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    We study the effect of a Chern-Simons (CS) term in the phase structure of two different Abelian gauge theories. For the compact Maxwell-Chern-Simons theory, we obtain that for values g=n/2πg=n/2\pi of the CS coupling with n=±1,±2n=\pm 1,\pm 2, the theory is equivalent to a gas of closed loops with contact interaction, exhibiting a phase transition in the 3dXY3dXY universality class. We also employ Monte Carlo simulations to study the noncompact U(1) Abelian Higgs model with a CS term. Finite size scaling of the third moment of the action yields critical exponents α\alpha and ν\nu that vary continuously with the strength of the CS term, and a comparison with available analytical results is made.Comment: RevTex4, 4 pages, 1 figure; v3: improvements and corrections made in the first part of the paper; references added. To be published in Europhysics Letter

    Compact U(1) gauge theories in 2+1 dimensions and the physics of low dimensional insulating materials

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    Compact abelian gauge theories in d=2+1d=2+1 dimensions arise often as an effective field-theoretic description of models of quantum insulators. In this paper we review some recent results about the compact abelian Higgs model in d=2+1d=2+1 in that context.Comment: 5 pages, 3 figures; based on talk by F.S. Nogueira in the Aachen HEP2003 conferenc

    Non-Gaussian state generation certified using the EPR-steering inequality

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    Due to practical reasons, experimental and theoretical continuous-variable (CV) quantum information (QI) has been heavily based on Gaussian states. Nevertheless, many CV-QI protocols require the use of non-Gaussian states and operations. Here, we show that the Einstein-Podolsky-Rosen steering inequality can be used to obtain a practical witness for the generation of pure bipartite non-Gaussian states. While the scenario require pure states, we show its broad relevance by reporting the experimental observation of the non-Gaussianity of the CV two-photon state generated in the process of spontaneous parametric down-conversion (SPDC). The observed non-Gaussianity is due only to the intrinsic phase-matching conditions of SPDCComment: 6 pages, 5 figure

    Three-body bound states with zero-range interaction in the Bethe-Salpeter approach

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    The Bethe-Salpeter equation for three bosons with zero-range interaction is solved for the first time. For comparison the light-front equation is also solved. The input is the two-body scattering length and the outputs are the three-body binding energies, Bethe-Salpeter amplitudes and light-front wave functions. Three different regimes are analyzed: ({\it i}) For weak enough two-body interaction the three-body system is unbound. ({\it ii}) For stronger two-body interaction a three-body bound state appears. It provides an interesting example of a deeply bound Borromean system. ({\it iii}) For even stronger two-body interaction this state becomes unphysical with a negative mass squared. However, another physical (excited) state appears, found previously in light-front calculations. The Bethe-Salpeter approach implicitly incorporates three-body forces of relativistic origin, which are attractive and increase the binding energy.Comment: 13 pages, 7 figure

    Multifractal Properties of Aperiodic Ising Model: role of geometric fluctuations

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    The role of the geometric fluctuations on the multifractal properties of the local magnetization of aperiodic ferromagnetic Ising models on hierachical lattices is investigated. The geometric fluctuations are introduced by generalized Fibonacci sequences. The local magnetization is evaluated via an exact recurrent procedure encompassing a real space renormalization group decimation. The symmetries of the local magnetization patterns induced by the aperiodic couplings is found to be strongly (weakly) different, with respect to the ones of the corresponding homogeneous systems, when the geometric fluctuations are relevant (irrelevant) to change the critical properties of the system. At the criticality, the measure defined by the local magnetization is found to exhibit a non-trivial F(alpha) spectra being shifted to higher values of alpha when relevant geometric fluctuations are considered. The critical exponents are found to be related with some special points of the F(alpha) function and agree with previous results obtained by the quite distinct transfer matrix approach.Comment: 10 pages, 7 figures, 3 Tables, 17 reference

    Liposomal formulations for rheumatoid arthritis

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    Book of Abstracts of CEB Annual Meeting 2017[Excerpt] Rheumatoid arthritis (RA) is the most common inflammatory rheumatic disease, affecting almost 1% of the world population. Although the cause of RA remains unknown, the complex interaction between immune mediators (cytokines and effector cells) is responsible for the joint damage that begins at the synovial membrane. Activated macrophages are critical in the pathogenesis of RA and showed specifically express a receptor for the vitamin folic acid (FA), folate receptor β (FRβ). This particular receptor allows internalization of FA-coupled cargo. [...]info:eu-repo/semantics/publishedVersio

    Bound state structure and electromagnetic form factor beyond the ladder approximation

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    We investigate the response of the bound state structure of a two-boson system, within a Yukawa model with a scalar boson exchange, to the inclusion of the cross-ladder contribution to the ladder kernel of the Bethe-Salpeter equation. The equation is solved by means of the Nakanishi integral representation and light-front projection. The valence light-front wave function and the elastic electromagnetic form factor beyond the impulse approximation, with the inclusion of the two-body current, generated by the cross-ladder kernel, are computed. The valence wave function and electromagnetic form factor, considering both ladder and ladder plus cross-ladder kernels, are studied in detail. Their asymptotic forms are found to be quite independent of the inclusion of the cross-ladder kernel, for a given binding energy. The asymptotic decrease of form factor agrees with the counting rules. This analysis can be generalized to fermionic systems, with a wide application in the study of the meson structure.Comment: 19 pages, 6 figures, submitted to Phys. Lett.
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