529 research outputs found

    Holographic duals of SQCD models in low dimensions

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    We obtain gravity duals to supersymmetric gauge theories in two and three spacetime dimensions with unquenched flavor. The supergravity solutions are generated by a set of color branes wrapping a compact cycle in a Calabi-Yau threefold, together with another set of flavor branes extended along the directions orthogonal to the cycle wrapped by the color branes. We construct supergravity backgrounds which include the backreaction induced by a smeared set of flavor branes, which act as delocalized dynamical sources of the different supergravity fields.Comment: 42 pages, 5 figures;v2: typos correcte

    Elaborations on the String Dual to N=1 SQCD

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    In this paper we make further refinements to the duality proposed between N=1 SQCD and certain string (supergravity plus branes) backgrounds, working in the regime of comparable large number of colors and flavors. Using the string theory solutions, we predict different field theory observables and phenomena like Seiberg duality, gauge coupling and its running, the behavior of Wilson and 't Hooft loops, anomalous dimensions of the quark superfields, quartic superpotential coupling and its running, continuous and discrete anomaly matching. We also give evidence for the smooth interpolation between higgsed and confining vacua. We provide several matchings between field theory and string theory computations.Comment: 44 pages, 6 figures. References added, minor rewritings, published versio

    Glueball Spectra of SQCD-like Theories

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    We study the spectrum of scalar glueballs in SQCD-like theories whose gravity description is in terms of Nc D5 color branes wrapped on an S^2 inside a CY3-fold, and Nf backreacting D5 flavor branes wrapped on a non-compact two-cycle inside the same CY3-fold. We show that there exists a consistent truncation of the ten-dimensional Type IIB supergravity system to a five-dimensional non-linear sigma model consisting of four scalars coupled to gravity. Studying fluctuations of the scalars as well as the metric around particular backgrounds allows us to compute their spectra. A few different backgrounds share the same qualitative features, namely that the mass of the lightest scalar glueball increases as the number of flavors is increased, until one reaches the point Nf = 2 Nc after which the opposite behaviour is obtained. We show that the five-dimensional non-linear sigma model obeys Seiberg duality, and demonstrate this explicitly for the spectra of a class of backgrounds that are Seiberg dual to themselves.Comment: 34 pages, 7 figures. Discussion of field theory added. Version to be published in JHEP

    D3-D7 Quark-Gluon Plasmas at Finite Baryon Density

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    We present the string dual to SU(Nc) N=4 SYM, coupled to Nf massless fundamental flavors, at finite temperature and baryon density. The solution is determined by two dimensionless parameters, both depending on the 't Hooft coupling λh\lambda_h at the scale set by the temperature T: ϵh∼λhNf/Nc\epsilon_h\sim\lambda_h Nf/Nc, weighting the backreaction of the flavor fields and δ~∼λh−1/2nb/(NfT3)\tilde\delta\sim\lambda_h^{-1/2}nb/(Nf T^3), where nbnb is the baryon density. For small values of these two parameters the solution is given analytically up to second order. We study the thermodynamics of the system in the canonical and grand-canonical ensembles. We then analyze the energy loss of partons moving through the plasma, computing the jet quenching parameter and studying its dependence on the baryon density. Finally, we analyze certain "optical" properties of the plasma. The whole setup is generalized to non abelian strongly coupled plasmas engineered on D3-D7 systems with D3-branes placed at the tip of a generic singular Calabi-Yau cone. In all the cases, fundamental matter fields are introduced by means of homogeneously smeared D7-branes and the flavor symmetry group is thus a product of abelian factors.Comment: 27 pages; v2: 29 pages, 1 (new) figure, new section 4.4 on optical properties, references, comments added; v3: eq. (3.19), comments and a reference adde

    On the Geometry of Matrix Models for N=1*

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    We investigate the geometry of the matrix model associated with an N=1 super Yang-Mills theory with three adjoint fields, which is a massive deformation of N=4. We study in particular the Riemann surface underlying solutions with arbitrary number of cuts. We show that an interesting geometrical structure emerges where the Riemann surface is related on-shell to the Donagi-Witten spectral curve. We explicitly identify the quantum field theory resolvents in terms of geometrical data on the surface.Comment: 17 pages, 2 figures. v2: reference adde

    Anàlisi del perfil del formador de formadors des de la perspectiva practicoreflexiva a les Illes Balears

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    academic plagiarism, cyberplagiarism, academic fraud, higher education, academic dishonesty, academic integrityLa finalitat de la recerca fou elaborar el mapa competencial del formador de formadors per tal d’optimitzar-ne el desenvolupament professional en el marc de les Illes Balears. D’acord amb això, la recerca va dedicar els seus recursos a identificar les qualitats personals i les competències de referència dels formadors de formadors. Per tal d’establir l’estat de la qüestió del tema d’estudi, a partir de la realització d’una anàlisi documental, es presenta la situació actual del concepte de competència, de formador practicoreflexiu i es fa una aproximació a les principals aportacions sobre les competències dels formadors. La recerca que presentam és de tipus qualitatiu i s’ha basat en la metodologia fenomenogràfica a partir de la realització de cinc grups de discussió, que comptaren amb la participació de trenta-tres informadors clau de diversos àmbits de la temàtica d’estudi. Per realitzar l’anàlisi interpretativa s’utilitzà el mètode de comparació constant, que va permetre classificar i analitzar la informació aportada pels experts. A partir d’aquesta informació es va establir un mapa de vuit qualitats personals i nou unitats de competència dels formadors de formadors, que dibuixen un professional amb un perfil d’acompanyament del procés de canvi i de reflexió sobre la seva pràctica. Aquest mapa competencial, sens dubte ha d’esdevenir un element clau per a la millora d’aquest professional a curt termini.The purpose of this research study was to develop a competency map of teacher trainers to maximise their professional development within the framework of the Balearic Islands. Accordingly, the study devoted its resources to identifying teacher trainers’ personal qualities and competencies of reference. To establish the state of the subject of study, the current status of the concept of competence and reflective-practical trainers is presented and the main input on the trainers’ skills are outlined on the basis of a documentary analysis. The present study is qualitative and based on the phenomenographic methodology using five discussion groups with the participation of thirty-three key informants from the various thematic areas of study. To conduct the interpretive analysis, the study used the Constant Comparative Method, which allowed the information provided by experts to be classified and analysed. This information was used to establish a map of eight personal qualities and nine units of competence for the teacher trainers that outlined a professional profile that accompanied the process of change and reflection on their practice. This competency map is undoubtedly a key element in improving professionals in the short term

    Phases and geometry of the N=1 A_2 quiver gauge theory and matrix models

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    We study the phases and geometry of the N=1 A_2 quiver gauge theory using matrix models and a generalized Konishi anomaly. We consider the theory both in the Coulomb and Higgs phases. Solving the anomaly equations, we find that a meromorphic one-form sigma(z)dz is naturally defined on the curve Sigma associated to the theory. Using the Dijkgraaf-Vafa conjecture, we evaluate the effective low-energy superpotential and demonstrate that its equations of motion can be translated into a geometric property of Sigma: sigma(z)dz has integer periods around all compact cycles. This ensures that there exists on Sigma a meromorphic function whose logarithm sigma(z)dz is the differential. We argue that the surface determined by this function is the N=2 Seiberg-Witten curve of the theory.Comment: 41 pages, 2 figures, JHEP style. v2: references adde

    Field and temperature dependence of magnetization in FeCu-based amorphous alloys

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    In this paper, the production of FeCu-based FeCuZr amorphous alloys by ball milling is reported. The thermal dependence of magnetization for the [Fe_(0.5)Cu_(0.5)]_85Zr_(15) (at. %) amorphous alloy has been found to show a dramatic field dependence of the kink point of the magnetization. This kink corresponds to a temperature different from the Curie temperature, above 400 K, of the ferromagnetic phase, which, according to spin waves fitting, can be induced by applying external fields. Just above 235 K, the thermoremanence increases sharply, and this feature strongly suggests an increase of the ferromagnetic ordering under zero field heating. Neutron diffraction experiments seem to confirm the enhancement of spin alignment. The thermal expansion above the compensation temperature is proposed to be the origin of the thermoremanence enhancement through the anti-Invar effect as might be explained within the framework of recent ab initio calculations [M. van Schilfgaarde et al., Nature (London) 400, 46 (1999)]

    Paretic syndrome in gulls from southern Portugal: searching for the causative agent

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    Between 2010 and 2019, 2.432 gulls (Larus michahellis and Larus fuscus) with paretic syndrome were received at RIAS Wildlife Rehabilitation and Research Centre. The clinical signs included weakness, anorexia, paralysis, diarrhoea (flaccid cloacae), dyspnoea and, in some cases, death. Several biotic contaminants are among the potential cause of this syndrome: marine biotoxins, Clostridium botulinum, cyanotoxins and virus. This presentation compiles the results of the Clostridium botulinum and marine biotoxins analysis conducted at the French National Reference Centre for anaerobic bacteria and botulism, Pasteur Institute (Paris) and the Vigo Centre of the Spanish Oceanographic Institute, respectively. C. botulinum analyses were conducted in livers and intestines from 5 gulls with paretic syndrome symptoms admitted at RIAS Wildlife Rehabilitation and Research Centre. Samples were pooled in two groups according to the tissue and analysed by targeted Real Time Polymerase Chain Reaction (PCR) on neurotoxin genes after sample enrichment culture under anaerobic conditions. The presence of botulinum toxin was confirmed by a lethality test on mice (mouse bioassay). Mice were intraperitoneally injected with filtered supernatant of the culture. Paralytic shellfish toxins (PSTs) were analysed by Liquid Chromatography with Fluorescence Detection and Post-column Oxidation in samples from ten gull kidneys and in the cloacae contents from another gull. Domoic acid (DA) analysis was conducted following a procedure that involved a methanolic extraction and analysis by Liquid Chromatography coupled to High Resolution Mass Spectrometry. DA was analysed in twenty three gull samples: ten livers, ten intestines and three cloacae contents. PSTs and DA were not detected in any of the samples tested. Results obtained so far point to C. botulimum type C/D as the causative agent of the paretic syndrome in gulls

    Quivers via anomaly chains

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    We study quivers in the context of matrix models. We introduce chains of generalized Konishi anomalies to write the quadratic and cubic equations that constrain the resolvents of general affine and non-affine quiver gauge theories, and give a procedure to calculate all higher-order relations. For these theories we also evaluate, as functions of the resolvents, VEV's of chiral operators with two and four bifundamental insertions. As an example of the general procedure we explicitly consider the two simplest quivers A2 and A1(affine), obtaining in the first case a cubic algebraic curve, and for the affine theory the same equation as that of U(N) theories with adjoint matter, successfully reproducing the RG cascade result.Comment: 32 pages, latex; typos corrected, published versio
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