204 research outputs found

    Influence of magnetic fields on the color screening masses

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    We present some recent results obtained in the study of the color magnetic and electric screening masses in the QCD plasma. In particular, we discuss how the masses get modified by strong external fields which are expected to be created in physical situations such as heavy-ion collisions.Comment: Talk presented at the 35th annual International Symposium on Lattice Field Theory (LATTICE 2017), 18-24 June 2017, Granada, Spain. 8 Pages, 7 Figure

    Magnetic field effects on the static quark potential at zero and finite temperature

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    We investigate the static QQˉQ\bar{Q} potential at zero and finite temperature in the presence of a constant and uniform external magnetic field B⃗\vec{B}, for several values of the lattice spacing and for different orientations with respect to B⃗\vec{B}. As a byproduct, we provide continuum limit extrapolated results for the string tension, the Coulomb coupling and the Sommer parameter at T=0T = 0 and B=0B = 0. We confirm the presence in the continuum of a BB-induced anisotropy, regarding essentially the string tension, for which it is of the order of 15\% at ∣e∣B∼1 GeV2|e| B \sim 1~{\rm GeV}^2 and would suggest, if extrapolated to larger fields, a vanishing string tension along the magnetic field for ∣e∣B≳4|e| B \gtrsim 4 GeV2^2. The angular dependence for ∣e∣B≲1|e| B \lesssim 1 GeV2^2 can be nicely parametrized by the first allowed term in an angular Fourier expansion, corresponding to a quadrupole deformation. Finally, for T≠0T \neq 0, the main effect of the magnetic field is a general suppression of the string tension, leading to a precocious loss of the confining properties: this happens even before the appearance of inverse magnetic catalysis in the chiral condensate, supporting the idea that the influence of the magnetic field on the confining properties is the leading effect originating the decrease of TcT_c as a function of BB.Comment: 13 pages, 4 tables, 14 figure

    Flux tubes in Nf=2+1N_f=2+1 QCD with external magnetic fields

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    We study the behavior of the confining flux tube in Nf=2+1N_f=2+1 QCD at the physical point, discretized with the stout smearing improved staggered quark action and the tree level Symanzik gauge action. We discuss how it depends on a uniform external magnetic field, showing how it displays anisotropies with respect to the magnetic field direction. Moreover, we compare the observed anisotropy pattern with that of the static quark-antiquark potential we obtained in our previous works.Comment: 8 pages, 35th International Symposium on Lattice Field Theory, Granada, Spai

    Screening masses in strong external magnetic fields

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    We present results for the (color)magnetic and (color)electric screening masses of the Quark-Gluon Plasma in the presence of an external magnetic field. The screening masses are extracted from the correlators of Polyakov loops, determined by lattice QCD simulations at the physical point. We explore temperatures in the range 200 MeV≲T≲330 MeV200\,\mathrm{MeV}\lesssim T\lesssim 330\,\mathrm{MeV} and magnetic field intensities up to ∣e∣B∼1.3 GeV2|e|B \sim 1.3\,\mathrm{GeV}^2. We find that both screening masses are increasing functions of the magnetic field and that the dependence on BB becomes weaker for larger temperatures. In the case of the magnetic screening mass a slight anisotropy is also observable.Comment: 8 pages, 2 tables, 10 eps figures; This version matches the published on

    fB and fBs with maximally twisted Wilson fermions

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    We present a lattice QCD calculation of the heavy-light decay constants fB and fBs performed with Nf = 2 maximally twisted Wilson fermions, at four values of the lattice spacing. The decay constants have been also computed in the static limit and the results are used to interpolate the observables between the charmand the infinite-mass sectors, thus obtaining the value of the decay constants at the physical b quark mass. Our preliminary results are fB = 191(14)MeV, fBs = 243(14)MeV, fBs/ fB = 1.27(5). They are in good agreement with those obtained with a novel approach, recently proposed by our Collaboration (ETMC), based on the use of suitable ratios having an exactly known static limit

    Levosimendan for patients with severely reduced left ventricular systolic function and/or low cardiac output syndrome undergoing cardiac surgery. a systematic review and meta-analysis

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    Background: Previous studies have shown beneficial effects of levosimendan in high-risk patients undergoing cardiac surgery. Two large randomized controlled trials (RCTs), however, showed no advantages of levosimendan. Methods: We performed a systematic review and meta-analysis (MEDLINE and Embase from inception until March 30, 2017), investigating whether levosimendan offers advantages compared with placebo in high-risk cardiac surgery patients, as defined by preoperative left ventricular ejection fraction (LVEF) = 35% and/or low cardiac output syndrome (LCOS). The primary outcomes were mortality at longest follow-up and need for postoperative renal replacement therapy (RRT). Secondary postoperative outcomes investigated included myocardial injury, supraventricular arrhythmias, development of LCOS, acute kidney injury (AKI), duration of mechanical ventilation, intensive care unit and hospital lengths of stay, and incidence of hypotension during drug infusion. Results: Six RCTs were included in the meta-analysis, five of which investigated only patients with LVEF = 35% and one of which included predominantly patients with LCOS. Mortality was similar overall (OR 0.64 [0.37, 1.11], p = 0.11) but lower in the subgroup with LVEF < 35% (OR 0.51 [0.32, 0.82], p = 0.005). Need for RRT was reduced by levosimendan both overall (OR 0.63 [0.42, 0.94], p = 0.02) and in patients with LVEF < 35% (OR 0.55 [0.31, 0.97], p = 0.04). Among secondary outcomes, we found lower postoperative LCOS in patients with LVEF < 35% receiving levosimendan (OR 0.49 [0.27, 0.89], p = 0.02), lower overall AKI (OR 0.62 [0.42, 0.92], p = 0.02), and a trend toward lower mechanical support, both overall (p = 0.07) and in patients with LVEF < 35% (p= 0.05). Conclusions: Levosimendan reduces mortality in patients with preoperative severely reduced LVEF but does not affect overall mortality. Levosimendan reduces the need for RRT after high-risk cardiac surger

    Effects of a strong magnetic field on the QCD flux tube

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    In this work we investigate the effect of an external magnetic field B on the shape of flux tubes in QCD by means of lattice simulations, performed with N_f=2+1 flavors of stout improved dynamical staggered quarks with physical masses. After having discussed some difficulties in the practical definition of the flux tube at B=0, we show that these ambiguities do not affect the determination of the flux tube modifications induced by the magnetic field. Different results are obtained depending on the relative orientations of the flux tube and of the magnetic field: they confirm that the magnetic field acts as transverse confinement catalyser and longitudinal confinement inhibitor; moreover, the flux tube itself loses its axial symmetry when it is not directed along the magnetic background.Comment: 11 pages, 14 eps figures, minor correction

    Radiation Macular Edema after Ru-106 Plaque Brachytherapy for Choroidal Melanoma Resolved by an Intravitreal Dexamethasone 0.7-mg Implant

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    Purpose: To report the effective treatment of radiation macular edema following ruthenium-106 plaque brachytherapy for a choroidal melanoma with a dexamethasone 0.7-mg (Ozurdex®) intravitreal implant. Methods: An interventional case report with optical coherence tomography (OCT) scans. Results: A 65-year-old Caucasian woman was suffering from radiation macular edema following ruthenium-106 plaque brachytherapy for a choroidal melanoma on her left eye. She had undergone one intravitreal injection of 0.5 mg bevacizumab (Avastin®, Genentech/Roche) in the following months without functional or anatomical improvement. Seven months after the development of radiation macular edema, she received a single intravitreal injection of dexamethasone 0.7 mg (Ozurdex). Four weeks following the injection, her best-corrected visual acuity improved from 0.3 to 0.5. Radiation macular edema resolved with a reduction of central retinal thickness from 498 µm before Ozurdex injection to 224 µm after Ozurdex injection, as measured by OCT scan. Conclusion: Dexamethasone 0.7 mg (Ozurdex) has proven to be an effective treatment option in retinal vein occlusion and noninfectious uveitis. It can also be considered as off-label treatment in radiation macular edema following ruthenium-106 plaque brachytherapy for a choroidal melanoma

    Gauge-invariant screening masses and static quark free energies in Nf=2+1 QCD at nonzero baryon density

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    We discuss the extension of gauge-invariant electric and magnetic screening masses in the quark-gluon plasma to the case of a finite baryon density, defining them in terms of a matrix of Polyakov loop correlators. We present lattice results for Nf=2+1 QCD with physical quark masses, obtained using the imaginary chemical potential approach, which indicate that the screening masses increase as a function of μB. A separate analysis is carried out for the theoretically interesting case μB/T=3iπ, where charge conjugation is not explicitly broken and the usual definition of the screening masses can be used for temperatures below the Roberge-Weiss transition. Finally, we investigate the dependence of the static quark free energy on the baryon chemical potential, showing that it is a decreasing function of μB, which displays a peculiar behavior as the pseudocritical transition temperature at μB=0 is approached
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