529 research outputs found
Holographic duals of SQCD models in low dimensions
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
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
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
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 at the scale set by the temperature T:
, weighting the backreaction of the flavor
fields and , where 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*
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
Anà lisi del perfil del formador de formadors des de la perspectiva practicoreflexiva a les Illes Balears
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 anà lisi 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 fenomenogrà fica a partir de la realització de cinc grups de discussió, que comptaren amb la participació de trenta-tres informadors clau de diversos à mbits de la temà tica d’estudi. Per realitzar l’anà lisi 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 prà ctica. 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
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
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
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
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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