18,445 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

    Interplay between chiral and axial symmetries in a SU(2) Nambu--Jona-Lasinio Model with the Polyakov loop

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    We consider a two flavor Polyakov--Nambu--Jona-Lasinio (PNJL) model where the Lagrangian includes an interaction term that explicitly breaks the UA(1)_A(1) anomaly. At finite temperature, the restoration of chiral and axial symmetries, signaled by the behavior of several observables, is investigated. We compare the effects of two regularizations at finite temperature, one of them, that allows high momentum quarks states, leading to the full recovery of chiral symmetry. From the analysis of the behavior of the topological susceptibility and of the mesonic masses of the axial partners, it is found in the SU(2) model that, unlike the SU(3) results, the recovery of the axial symmetry is not a consequence of the full recovery of the chiral symmetry. Thus, one needs to use an additional idea, by means of a temperature dependence of the anomaly coefficient, that simulates instanton suppression effects.Comment: 21 pages, 5 figures; PRD versio

    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
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