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52
Stringy NJL and GrossNeveu models at finite density and temperature,” arXiv:0708.0589 [hepth
"... Abstract: Nonlocal stringy versions of the NambuJonaLasinio and GrossNeveu models arise in a certain limit of holographic QCD. We analyze the phase structure at finite density and temperature at strong coupling in terms of probe branes in the gravity dual. Comparison with the phase structure of t ..."
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Cited by 26 (3 self)
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Abstract: Nonlocal stringy versions of the NambuJonaLasinio and GrossNeveu models arise in a certain limit of holographic QCD. We analyze the phase structure at finite density and temperature at strong coupling in terms of probe branes in the gravity dual. Comparison with the phase structure of the local field theory models shows qualitative agreement with some aspects, and disagreement with others. Finally, we explain how to construct the Landau potentials for these models by taking the probe branes offshell. Contents
Interpolating between low and high energy QCD via a 5D YangMills model
, 2005
"... We describe the Goldstone bosons of massless QCD together with an infinite number of spin1 mesons. The field content of the model is SU(Nf) × SU(Nf) YangMills in a compact extradimension. Electroweak interactions reside on one brane. Breaking of chiral symmetry occurs due to the boundary condi ..."
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Cited by 25 (3 self)
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We describe the Goldstone bosons of massless QCD together with an infinite number of spin1 mesons. The field content of the model is SU(Nf) × SU(Nf) YangMills in a compact extradimension. Electroweak interactions reside on one brane. Breaking of chiral symmetry occurs due to the boundary conditions on the other brane, away from our world, and is therefore spontaneous. Our implementation of the holographic recipe maintains chiral symmetry explicit throughout. For intermediate energies, we extract resonance couplings. These satisfy sum rules due to the 5D nature of the model. These sum rules imply, when taking the highenergy limit, that perturbative QCD constraints are satisfied. We also illustrate how the 5D model implies a definite prescription for handling infinite sums over 4D resonances. Taking the lowenergy limit, we recover the chiral expansion and the corresponding nonlocal order parameters. All local order parameters are introduced separately.
Excited Mesons and Quantization of String Endpoints
, 2004
"... We argue that those field theories containing mesons that are dual to weakly curved string backgrounds are non–generic. The spectrum of highly excited mesons in confining field theories behaves as Mn ∝ √ n (where n is the radial excitation number), as does the spectrum of the dual mesons described ..."
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Cited by 16 (0 self)
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We argue that those field theories containing mesons that are dual to weakly curved string backgrounds are non–generic. The spectrum of highly excited mesons in confining field theories behaves as Mn ∝ √ n (where n is the radial excitation number), as does the spectrum of the dual mesons described by open strings ending on probe D branes. However, in the weakly coupled backgrounds, we show that the sector of (light) mesons with spin J ≤ 1, dual to the brane fluctuations, behaves as Mn ∝ n, for confining and non–confining theories alike. In order to perform the analysis we suggest a method of quantization of the open string endpoints, and rely
Dynamics of baryons from string theory and vector dominance”, arXiv:0705.2632 [hepth
"... We consider a holographic model of QCD from string theory, à la Sakai and Sugimoto, and study baryons. In this model, mesons are collectively realized as a fivedimensional U(NF) = U(1) × SU(NF) YangMills field and baryons are classically identified as SU(NF) solitons with a unit Pontryagin numbe ..."
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Cited by 14 (1 self)
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We consider a holographic model of QCD from string theory, à la Sakai and Sugimoto, and study baryons. In this model, mesons are collectively realized as a fivedimensional U(NF) = U(1) × SU(NF) YangMills field and baryons are classically identified as SU(NF) solitons with a unit Pontryagin number and Nc electric charges. The soliton is shown to be very small in the large ’t Hooft coupling limit, allowing us to introduce an effective field B. Its coupling to the mesons are dictated by the soliton structure, and consists of a direct magnetic coupling to the SU(NF) field strength as well as a minimal coupling to the U(NF) gauge field. Upon the dimensional reduction, this effective action reproduces all interaction terms between nucleons and an infinite tower of mesons in a manner consistent with the large Nc expansion. We further find that all electromagnetic interactions, as inferred from the same effective action via a holographic prescription, are mediated by an infinite tower of vector mesons, rendering the baryon electromagnetic form factors completely
R.C.: Magnetic Catalysis of Chiral Symmetry Breaking. A Holographic Prospective
 Adv. High Energy Phys
, 2010
"... We review a recent investigation of the effect of magnetic catalysis of mass generation in holographic YangMills theories. We aim at a selfcontained and pedagogical form of the review. We provide a brief field theory background and review the basics of holographic flavordynamics. The main part of ..."
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Cited by 12 (1 self)
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We review a recent investigation of the effect of magnetic catalysis of mass generation in holographic YangMills theories. We aim at a selfcontained and pedagogical form of the review. We provide a brief field theory background and review the basics of holographic flavordynamics. The main part of the paper investigates the influence of external magnetic field to holographic gauge theories dual to the D3/D5and D3/D7brane intersections. Among the observed phenomena are the spontaneous breaking of a global internal symmetry, Zeeman splitting of the energy levels, and the existence of pseudo, Goldstone modes. An analytic derivation of the GellMannOaksRenner relation for the D3/D7 set up is reviewed. In the D3/D5 case, the pseudoGoldstone modes satisfy nonrelativistic dispersion relation. The studies reviewed confirm the universal nature of the magnetic catalysis of mass generation.
On string junctions in supersymmetric gauge theories,” Prog
 Theor. Phys
, 2004
"... We study junctions consisting of confining strings in N = 1 supersymmetric large N gauge theories by means of the gauge/gravity correspondence. We realize these junctions as Dbrane configurations in infrared geometries of the KlebanovStrassler (KS) and the MaldacenaNúñez (MN) solutions. After dis ..."
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Cited by 11 (0 self)
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We study junctions consisting of confining strings in N = 1 supersymmetric large N gauge theories by means of the gauge/gravity correspondence. We realize these junctions as Dbrane configurations in infrared geometries of the KlebanovStrassler (KS) and the MaldacenaNúñez (MN) solutions. After discussing kinematics associated with the balance of tensions, we compute the energies of baryon vertices numerically. In the KS background, baryon vertices give negative contributions to the energies. The results for the MN background strongly suggest that the energies of baryon vertices exactly vanish, as in the case of supersymmetric (p, q)string junctions. We find that brane configurations in the MN background have a property similar to the holomorphy of the Mtheory realization of (p, q)string junctions. With the help of this property, we analytically prove the vanishing of the energies of baryon vertices in the MN background.
Supersymmetric probes on the conifold
 J. High Energy Phys
"... We study the supersymmetric embeddings of different Dbrane probes in the AdS5 × T 1,1 geometry. The main tool employed is kappa symmetry and the cases studied include D3, D5 and D7branes. We find a family of threecycles of the T 1,1 space over which a D3brane can be wrapped supersymmetrically ..."
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Cited by 6 (1 self)
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We study the supersymmetric embeddings of different Dbrane probes in the AdS5 × T 1,1 geometry. The main tool employed is kappa symmetry and the cases studied include D3, D5 and D7branes. We find a family of threecycles of the T 1,1 space over which a D3brane can be wrapped supersymmetrically and we determine the field content of the corresponding gauge theory duals. Supersymmetric configurations of D5branes wrapping a twocycle and of spacetime filling D7branes are also found. The configurations in which the entire T 1,1 space is wrapped by a D5brane (baryon vertex) and a D7brane are also studied. Some other embeddings which break supersymmetry but are nevertheless stable are also determined. hepth/0408210 August 2004
Holographic gauge theories in background fields and surface operators
 JHEP
"... We construct a new class of supersymmetric surface operators in N = 4 SYM and find the corresponding dual supergravity solutions. We show that the insertion of the surface operator – which is given by a WZW model supported on the surface – appears by integrating out the localized degrees of freedom ..."
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Cited by 6 (2 self)
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We construct a new class of supersymmetric surface operators in N = 4 SYM and find the corresponding dual supergravity solutions. We show that the insertion of the surface operator – which is given by a WZW model supported on the surface – appears by integrating out the localized degrees of freedom along the surface which arise microscopically from a D3/D7 brane intersection. Consistency requires constructing N = 4 SYM in the D7 supergravity background and not in flat space. This enlarges the class of holographic gauge theories dual to string theory backgrounds to gauge theories in nontrivial supergravity backgrounds. The dual Type IIB supergravity solutions we find reveal – among other features – that the holographic dual gauge theory does indeed live in the D7brane background.
Holographic aspects of three dimensional QCD from string theory, JHEP 05
, 2010
"... We study two aspects of 3D QCD with massless fermions in a holographic setup from string theory, based on D3/D7 branes; parity anomaly and baryons as baby Skyrmions. We first give a novel account of parity anomaly of 3D QCD with odd number of flavors from the IR holographic viewpoint by observing a ..."
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Cited by 4 (1 self)
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We study two aspects of 3D QCD with massless fermions in a holographic setup from string theory, based on D3/D7 branes; parity anomaly and baryons as baby Skyrmions. We first give a novel account of parity anomaly of 3D QCD with odd number of flavors from the IR holographic viewpoint by observing a subtle point in D7 brane embeddings with a given fixed UV theory. We also discuss its UV origin in terms of weakly coupled Dbrane pictures. We then focus on the paritysymmetric case of even number of NF flavors, and study baryons in the holographic model. We identify the monopoles of U(NF) gauge theory dynamically broken down to U( NF 2)×U(
Supersymmetric branes on AdS(5) × Y p,q and their field theory duals
 JHEP
, 2005
"... We systematically study supersymmetric embeddings of Dbrane probes of different dimensionality in the AdS5 × Y p,q background of type IIB string theory. The main technique employed is the kappa symmetry of the probe’s worldvolume theory. In the case of D3branes, we recover the known threecycles du ..."
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Cited by 3 (0 self)
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We systematically study supersymmetric embeddings of Dbrane probes of different dimensionality in the AdS5 × Y p,q background of type IIB string theory. The main technique employed is the kappa symmetry of the probe’s worldvolume theory. In the case of D3branes, we recover the known threecycles dual to the dibaryonic operators of the gauge theory and we also find a new family of supersymmetric embeddings. The BPS fluctuations of dibaryons are analyzed and shown to match the gauge theory results. Supersymmetric configurations of D5branes, representing domain walls, and of spacetime filling D7branes (which can be used to add flavor) are also found. We also study the baryon vertex and some other embeddings which break supersymmetry but are nevertheless stable.