36,435 research outputs found

    The pion mass dependence of the nucleon form-factors of the energy momentum tensor in the chiral quark-soliton model

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    The nucleon form factors of the energy-momentum tensor are studied in the large-Nc limit in the framework of the chiral quark-soliton model for model parameters that simulate physical situations in which pions are heavy. This allows for a direct comparison to lattice QCD results.Comment: 17 pages, 12 figure

    Diffusive Radiation in One-dimensional Langmuir Turbulence

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    We calculate spectra of radiation produced by a relativistic particle in the presence of one-dimensional Langmuir turbulence which might be generated by a streaming instability in the plasma, in particular, in the shock front or at the shock-shock interactions. The shape of the radiation spectra is shown to depend sensitively on the angle between the particle velocity and electric field direction. The radiation spectrum in the case of exactly transverse particle motion is degenerate and similar to that of spatially uniform Langmuir oscillations. In case of oblique propagation, the spectrum is more complex, it consists of a number of power-law regions and may contain a distinct high-frequency spectral peak. %at \omega=2\omega\pe \gamma^2. The emission process considered is relevant to various laboratory plasma settings and for astrophysical objects as gamma-ray bursts and collimated jets.Comment: 4 pages, 1 figure, accepted for Phys. Rev.

    Rashba spin precession in quantum Hall edge channels

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    Quasi--one dimensional edge channels are formed at the boundary of a two-dimensional electron system subject to a strong perpendicular magnetic field. We consider the effect of Rashba spin--orbit coupling, induced by structural inversion asymmetry, on their electronic and transport properties. Both our analytical and numerical results show that spin--split quantum--Hall edge channels exhibit properties analogous to that of Rashba--split quantum wires. Suppressed backscattering and a long spin life time render these edge channels an ideal system for observing voltage--controlled spin precession. Based on the latter, we propose a magnet--less spin--dependent electron interferometer.Comment: 7 pages, 6 figure

    A CDCL-style calculus for solving non-linear constraints

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    In this paper we propose a novel approach for checking satisfiability of non-linear constraints over the reals, called ksmt. The procedure is based on conflict resolution in CDCL style calculus, using a composition of symbolical and numerical methods. To deal with the non-linear components in case of conflicts we use numerically constructed restricted linearisations. This approach covers a large number of computable non-linear real functions such as polynomials, rational or trigonometrical functions and beyond. A prototypical implementation has been evaluated on several non-linear SMT-LIB examples and the results have been compared with state-of-the-art SMT solvers.Comment: 17 pages, 3 figures; accepted at FroCoS 2019; software available at <http://informatik.uni-trier.de/~brausse/ksmt/

    Entropy Functions with 5D Chern-Simons terms

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    In this note we reconsider Sen's entropy function analysis for 5D supergravity actions containing Chern-Simons terms. The apparent lack of gauge invariance is usually tackled via a 4D reduction. Here we motivate how a systematic 5D procedure also works. In doing so, it becomes important to identify the correct 5D charges. In particular, we perform explicit calculations for the black ring and 5D black hole. In the black ring analysis, we find Chern-Simons induced spectral flow shifts emerging out of Sen's formalism. We find that the entropy function nevertheless remains gauge invariant and the resulting electric charges are identified as Page charges. For the black hole too, 5D gauge invariance is confirmed. Our 5D analysis enables us to fix a mismatch that arose in the electric charges of Goldstein and Jena's 4D-reduced calculation. Finally we provide an interpretation for the e^0 - p^0 exchange in the entropy function as an interpolation between black hole and black ring geometries in Taub-NUT.Comment: 27 page

    Variabilidade genética de Fusarium decemcellulare isolado de três diferentes sintomas em guaranazeiro (Paullinia cupana var. sorbilis).

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    O objetivo deste trabalho foi analisar a variabilidade entre isolados obtidos de diferentes genótipos de guaranazeiro e de diferentes sintomas.Resumo:57-2

    Remarks on the notion of quantum integrability

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    We discuss the notion of integrability in quantum mechanics. Starting from a review of some definitions commonly used in the literature, we propose a different set of criteria, leading to a classification of models in terms of different integrability classes. We end by highlighting some of the expected physical properties associated to models fulfilling the proposed criteria.Comment: 22 pages, no figures, Proceedings of Statphys 2

    Asymmetric Fermi superfluid in a harmonic trap

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    We consider a dilute two-component atomic fermion gas with unequal populations in a harmonic trap potential using the mean field theory and the local density approximation. We show that the system is phase separated into concentric shells with the superfluid in the core surrounded by the normal fermion gas in both the weak-coupling BCS side and near the Feshbach resonance. In the strong-coupling BEC side, the composite bosons and left-over fermions can be mixed. We calculate the cloud radii and compare axial density profiles systemically for the BCS, near resonance and BEC regimes.Comment: 15 pages, 5 figure

    Spin-orbit terms in multi-subband electron systems: A bridge between bulk and two-dimensional Hamiltonians

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    We analyze the spin-orbit terms in multi-subband quasi-two-dimensional electron systems, and how they descend from the bulk Hamiltonian of the conduction band. Measurements of spin-orbit terms in one subband alone are shown to give incomplete information on the spin-orbit Hamiltonian of the system. They should be complemented by measurements of inter-subband spin-orbit matrix elements. Tuning electron energy levels with a quantizing magnetic field is proposed as an experimental approach to this problem.Comment: Typos noticed in the published version have been corrected and several references added. Published in the special issue of Semiconductors in memory of V.I. Pere
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