15,712 research outputs found

    Some properties of two Nambu--Jona-Lasinio -type models with inputs from lattice QCD

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    We investigate the phase diagram of the so-called Polyakov--Nambu--Jona-Lasinio (PNJL) model at finite temperature and nonzero chemical potential. The calculations are performed in the light and strange quark sectors (uu, dd, ss), which includes the 't Hooft instanton induced interaction term that breaks the axial symmetry, and the quarks are coupled to the (spatially constant) temporal background gauge field. On one hand, a special attention is payed to the critical end point (CEP). The strength of the flavor-mixing interaction alters the CEP location, since when it becomes weaker the CEP moves to low temperatures and can even disappear. On the other hand, we also explore the connection between QCD, a nonlocal Nambu--Jona-Lasinio type model and the Landau gauge gluon propagator. Possible links between the quenched gluon propagator and low energy hadronic phenomenology are investigated.Comment: Contribution to the International Meeting "Excited QCD", Peniche, Portugal, 06 - 12 May 201

    On the Nonlinear Impulsive Ψ\Psi--Hilfer Fractional Differential Equations

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    In this paper, we consider the nonlinear Ψ\Psi-Hilfer impulsive fractional differential equation. Our main objective is to derive the formula for the solution and examine the existence and uniqueness of results. The acquired results are extended to the nonlocal Ψ\Psi-Hilfer impulsive fractional differential equation. We gave an applications to the outcomes we procured. Further, examples are provided in support of the results we got.Comment: 2

    Resultados de pesquisa com trigo, triticale e aveia - 1999.

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    Comportamento climático durante o ciclo da cultura do trigo, em Dourados, MS, safra 1999; Avaliação de cultivares de trigo indicadas para cultivo em Mato Grosso do Sul, safra 1999; Avaliação de cultivares de trigo indicadas para cultivo em outros estados do Brasil, safra 1999; Ensaio brasileiro de genótipos de triticale em Dourados, MS, safra 1999; Ensaio brasileiro de cultivares de aveia branca em Dourados, MS, safra 1999.bitstream/item/65723/1/DOC38.pd

    The first radial velocity measurements of a microlensing event: no evidence for the predicted binary

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    The gravitational microlensing technique allows the discovery of exoplanets around stars distributed in the disk of the galaxy towards the bulge. However, the alignment of two stars that led to the discovery is unique over the timescale of a human life and cannot be re-observed. Moreover, the target host is often very faint and located in a crowded region. These difficulties hamper and often make impossible the follow-up of the target and study of its possible companions. Gould et al. (2013) predicted the radial-velocity curve of a binary system, OGLE-2011-BLG-0417, discovered and characterised from a microlensing event by Shin et al. (2012). We used the UVES spectrograph mounted at the VLT, ESO to derive precise radial-velocity measurements of OGLE-2011-BLG-0417. To gather high-precision on faint targets of microlensing events, we proposed to use the source star as a reference to measure the lens radial velocities. We obtained ten radial velocities on the putative V=18 lens with a dispersion of ~100 m/s, spread over one year. Our measurements do not confirm the microlensing prediction for this binary system. The most likely scenario is that the assumed V=18 mag lens is actually a blend and not the primary lens that is 2 magnitude fainter. Further observations and analyses are needed to understand the microlensing observation and infer on the nature and characteristics of the lens itself.Comment: submitted on 3rd June 2015 to A&ALette

    Phase Coherent Precessional Magnetization Reversal in Micro-scopic Spin Valve Elements

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    We study the precessional switching of the magnetization in microscopic spin valve cells induced by ultra short in-plane hard axis magnetic field pulses. Stable and highly efficient switching is monitored following pulses as short as 140 ps with energies down to 15 pJ. Multiple application of identical pulses reversibly toggles the cell's magnetization be-tween the two easy directions. Variations of pulse duration and amplitude reveal alter-nating regimes of switching and non-switching corresponding to transitions from in-phase to out-of-phase excitations of the magnetic precession by the field pulse. In the low field limit damping becomes predominant and a relaxational reversal is found allowing switching by hard axis fields below the in-plane anisotropy field threshold.Comment: 17 pages, 4 figure

    Effective restoration of the U_A(1) symmetry with temperature and density

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    We investigate the full U(3)\otimesU(3) chiral symmetry restoration, at finite temperature and density, on the basis of a quark model which incorporates the most relevant properties of QCD in this context: explicit and spontaneous breaking of chiral symmetry and axial UA_A(1) symmetry breaking. A specific lattice-inspired behavior of the topological susceptibility, combined with the convergence of chiral partners, signals the onset of an effective chiral symmetry restoration. The results suggest that the axial part of the symmetry is restored before the possible restoration of the full U(3)\otimesU(3) chiral symmetry can occur. This conclusion is valid in the context of both finite temperature and density.Comment: 5 pages, 2 figures; PRD versio
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