A magnetically induced quantum phase transition in holography

We investigate quantum phase transitions in a 2+1 dimensional gauge theory at finite chemical potential $\chi$ and magnetic field $B$. The gravity dual is based on 4D $\mathcal{N}=2$ Fayet-Iliopoulos gauged supergravity and the solutions we consider---that are constructed analytically---are extremal, dyonic, asymptotically $AdS_4$ black-branes with a nontrivial radial profile for the scalar field. We discover a line of second order fixed points at $B=B_c(\chi)$ between the dyonic black brane and an extremal "thermal gas" solution with a singularity of good-type, according to the acceptability criteria of Gubser [1]. The dual field theory is the ABJM theory [2] deformed by a triple trace operator $\Phi^3$ and placed at finite charge and magnetic field. This line of fixed points might be useful in studying the various strongly interacting quantum critical phenomena such as the ones proposed to underlie the cuprate superconductors. We also find curious similarities between the behaviour of the VeV $\langle \Phi \rangle$ under B and that of the quark condensate in 2+1 dimensional NJL models.Comment: 33 pages, 7 figure

Constraints on Conformal Windows from Holographic Duals

We analyze a beta function with the analytic form of Novikov-Shifman-Vainshtein-Zakharov result in the five dimensional gravity-dilaton environment. We show how dilaton inherits poles and fixed points of such beta function through the zeros and points of extremum in its potential. Super Yang-Mills and supersymmetric QCD are studied in detail and Seiberg's electric-magnetic duality in the dilaton potential is explicitly demonstrated. Non-supersymmetric proposals of similar functional form are tested and new insights into the conformal window as well as determinations of scheme-independent value of the anomalous dimension at the fixed point are presented.Comment: Fig. 5b is corrected to match the discussion in the tex

Polyakov Loops in Strongly-Coupled Plasmas with Gravity Duals

We study the properties of the Polyakov loop in strongly-coupled gauge plasmas that are conjectured to be dual to five dimensional theories of gravity coupled to a nontrivial single scalar field. We find a gravity dual that can describe the thermodynamic properties and also the expectation value of the Polyakov loop in the deconfined phase of quenched SU(3) QCD up to $3T_c$.Comment: 7 pages, 2 figures, talk presented at the International Conference on Strangeness in Quark Matter, Buzios, Rio de Janeiro, Brazil, Sept. 27 - oct. 2, 200

A Holographic Model of Strange Metals

We give a review on our recent work arXiv:1006.0779 [hep-th] and arXiv:1006.1719 [hep-th], in which properties of holographic strange metals were investigated. The background is chosen to be anisotropic scaling solution in Einstein-Maxwell-Dilaton theory with a Liouville potential. The effects of bulk Maxwell field, an extra U(1) gauge field and probe D-branes on the DC conductivity, the DC Hall conductivity and the AC conductivity are extensively analyzed. We classify behaviors of the conductivities according to the parameter ranges in the bulk theory and characterize conditions when the holographic results can reproduce experimental data.Comment: 34 pages, 15 figures, minor correction

On the YM and QCD spectra from five dimensional strings

We consider a non-critical five dimensional string setup which could provide a dual description of QCD in the limit of large number of colors and flavors. The model corresponds to N_c color D3-branes and N_f D4/anti D4-brane pairs supporting flavor degrees of freedom. The matching of the string model spectrum with the dual field theory one is considered. We discuss the consequences of the possible matching of the gravity modes with the light glueballs and the interpretation of the brane spectrum in Yang-Mills and QCD.Comment: 21 pages; V2: added corrections and references to match the published versio

Impact of trust on local residents' mega-event perceptions and their support

This study examines the influence of residents’ trust in government and organizing committee on their impact perceptions and support for a mega-event, namely, 2014 FIFA World Cup. Findings suggest significant relationships between impact perceptions and support. While trust in government is found to be a significant determinant of impact perceptions, findings indicate no significant relationship between trust in government and support, which suggest that the relationship is mediated by impact perceptions. While a positive relationship between trust in the organizing committee and positive impact perceptions is found, findings suggest no significant relationship between trust in the organizing committee and negative impact perceptions. Trust in the organizing committee is also found to have significant positive impact on support

Soft-Wall Stabilization

We propose a general class of five-dimensional soft-wall models with AdS metric near the ultraviolet brane and four-dimensional Poincar\'e invariance, where the infrared scale is determined dynamically. A large UV/IR hierarchy can be generated without any fine-tuning, thus solving the electroweak/Planck scale hierarchy problem. Generically, the spectrum of fluctuations is discrete with a level spacing (mass gap) provided by the inverse length of the wall, similar to RS1 models with Standard Model fields propagating in the bulk. Moreover two particularly interesting cases arise. They can describe: (a) a theory with a continuous spectrum above the mass gap which can model unparticles corresponding to operators of a CFT where the conformal symmetry is broken by a mass gap, and; (b) a theory with a discrete spectrum provided by linear Regge trajectories as in AdS/QCD models.Comment: 27 pages, 6 figures, 1 table. v2: references added, version to appear in NJP Focus Issue on Extra Dimension

Torsional Newton Cartan gravity from non-relativistic strings

We study propagation of closed bosonic strings in torsional Newton-Cartan geometry based on a recently proposed Polyakov type action derived by dimensional reduction of the ordinary bosonic string along a null direction. We generalize the Polyakov action proposal to include matter, i.e. the 2-form and the 1-form that originates from the Kalb-Ramond field and the dilaton. We determine the conditions for Weyl invariance which we express as the beta-function equations on the worldsheet, in analogy with the usual case of strings propagating on a pseudo-Riemannian manifold. The critical dimension of the TNC space-time turns out to be 25. We find that Newton's law of gravitation follows from the requirement of quantum Weyl invariance in the absence of torsion. Presence of the 1-form requires torsion to be non vanishing. Torsion has interesting consequences, in particular it yields a mass term and an advection term in the generalized Newton's law. U(1) mass invariance of the theory is an important ingredient in deriving the beta functions.Comment: Summary of results added. Reorganization and generalization of results. Typos fixe

Limiar entre a moda e a arte

As tendências de moda materializam-se e chegam aos consumidores, mas até lá passam por um processo criativo, que poderá ou não ser equiparado ao processo artístico? Sendo a moda concebida a partir do ensamento e leituras ou interpretações de seus criadores sobre o universo que o rodeia, poderá esta equiparar-se à arte ao traduzir as características do tempo em que foi criada? Será que estas vivem em esferas separadas, ou existe um diálogo permanente entre elas? Serão questões que tentaremos responder neste artigo, tentando analisar o limiar entre arte e moda