191 research outputs found
Magnetic catalysis in flavored ABJM
We study the magnetic catalysis of chiral symmetry breaking in the ABJM
Chern-Simons matter theory with unquenched flavors in the Veneziano limit. We
consider a magnetized D6-brane probe in the background of a flavored black hole
which includes the backreaction of massless smeared flavors in the ABJM
geometry. We find a holographic realization for the running of the quark mass
due to the dynamical flavors. We compute several thermodynamic quantities of
the brane probe and analyze the effects of the dynamical quarks on the
fundamental condensate and on the phase diagram of the model. The dynamical
flavors have an interesting effect on the magnetic catalysis. At zero
temperature and fixed magnetic field, the magnetic catalysis is suppressed for
small bare quark masses whereas it is enhanced for large values of the mass.
When the temperature is non-zero there is a critical magnetic field, above
which the magnetic catalysis takes place. This critical magnetic field
decreases with the number of flavors, which we interpret as an enhancement of
the catalysis.Comment: 33 pages, 11 figures; v2: refs added; v3: revised version, new
subsection on running mass added, discussion clarifie
Supersymmetric Baryonic Branes
We derive an energy bound for a `baryonic' D5-brane probe in the background near the horizon of D3-branes. Configurations saturating
the bound are shown to be 1/4 supersymmetric -wrapped D5-branes, with a
total Born-Infeld charge . Previous results are recovered as a special case.
We derive a similar energy bound for a `baryonic' M5-brane probe in the
background of M5-branes. Configurations saturating the bound are again 1/4
supersymmetric and, in the near-horizon limit, provide a
worldvolume realization of the `baryon string' vertex of the
(2,0)-supersymmetric six-dimensional conformal field theory on coincident
M5-branes. For the full M5-background we find a worldvolume realization of the
Hanany-Witten effect in M-theory.Comment: 32 pp. Third version is the same as the second except for a little
additional material. To appear in JHE
Non chiral dynamical flavors and screening on the conifold
We present a new class of string theory solutions which are conjectured to be
dual to the N=1 conifold theory by Klebanov and Witten coupled to non chiral
massive dynamical flavors. These are introduced, in the Veneziano limit, by
means of suitably embedded and smeared D7-branes whose full backreaction on the
background is taken into account. The string solutions are used to study
chromoelectric charge screening effects due to the dynamical flavors in the non
perturbative regime of the dual gauge theories.Comment: 6 pages, 1 figure, previously unpublished results presented.
Contribution to the proceedings of the RTN workshop "Constituents,
Fundamental Forces and Symmetries of the Universe", Varna, Bulgaria,
September 11-17, 200
D3-D5 theories with unquenched flavors
We construct the string duals of the defect theories generated when N_f
flavor D5-branes intersect N_c color D3-branes along a 2+1 dimensional
subspace. We work in the Veneziano limit in which N_c and N_f are large and
N_f/N_c is fixed. By smearing the D5-branes, we find supergravity solutions
that take into account the backreaction of the flavor branes and preserve two
supercharges. When the flavors are massless the resulting metric displays an
anisotropic Lifshitz-like scale invariance. The case of massive quarks is also
considered.Comment: 29 pages, 1 figure; v2: references adde
Quantum phase transitions with dynamical flavors
We study the properties of a D6-brane probe in the Aharony-Bergman-Jafferis-Maldacena (ABJM) background with smeared massless dynamical quarks in the Veneziano limit. Working at zero temperature and nonvanishing charge density, we show that the system undergoes a quantum phase transition in which the topology of the brane embedding changes from a black hole to a Minkowski embedding. In the unflavored background the phase transition is of second order and takes place when the charge density vanishes. We determine the corresponding critical exponents and show that the scaling behavior near the quantum critical point has multiplicative logarithmic corrections. In the background with dynamical quarks the phase transition is of first order and occurs at nonzero charge density. In this case we compute the discontinuity of several physical quantities as functions of the number N-f of unquenched quarks of the background.Peer reviewe
Cold holographic matter in the Higgs branch
We study collective excitations of cold (2 + 1)-dimensional fundamental matter living on a defect of the four-dimensional N = 4 super Yang-Mills theory in the Higgs branch. This system is realized holographically as a D3-D5 brane intersection, in which the D5-brane is treated as a probe with a non-zero gauge flux across the internal part of its worldvolume. We study the holographic zero sound mode in the collisionless regime at low temperature and find a simple analytic result for its dispersion relation. We also find the diffusion constant of the system in the hydrodynamic regime at higher temperature. In both cases we study the dependence on the flux parameter which determines the amount of Higgs symmetry breaking. We also discuss the anyonization of this construction. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license.Peer reviewe
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