Infrared Dynamics of a Large N QCD Model, the Massless String Sector and Mesonic Spectra

Dasgupta, Keshav; Gale, Charles; Mia, Mohammed; Richard, Michael; Trottier, Olivier

doi:10.48550/arxiv.1409.0559

Cited by 4 publications

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“…• As noted explicitly in the first reference in [22], the type IIA SYZ(Strominger-Yau-Zaslow) mirror of [2] on account of the mixing of the type IIB metric and the NS-NS B IIB under triple T duality, picks up sub-dominant terms in N of O 1 N κ , 0 < κ < 1 which are also of O(M 0 ) in B IIA (the non-conformality in type IIB in [2] is because of B IIB which is accompanied by M , the number of fractional D3 branes) which are therefore bigger than the O( gsM 2 N ) contributions, that were missed, e.g. in [51] in the context of top-down meson spectroscopy.…”

Section: Summary and Discussionmentioning

confidence: 99%

The QCD Trace Anomaly at Strong Coupling from M-Theory

Misra,

Gale

2019

Preprint

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In this short note we address the issue of obtaining the temperature dependence of the QCD conformal anomaly from a top-down holographic dual consistent with very recent lattice results for both, T < T c and T > T c . As the holographic dual, we use the M-theory uplift of the SYZ type IIA mirror obtained in [1] at finite gauge/string coupling (as part of the 'MQGP' limit) of the type IIB holographic dual of large-N thermal QCD of [2]. We also obtain a QCD deconfinement temperature T c = 150 MeV from a Hawking-Page phase transition at vanishing baryon chemical potential, consistent with lattice QCD in the heavy-quark limit.

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Section: Summary and Discussionmentioning

confidence: 99%

The QCD Trace Anomaly at Strong Coupling from M-Theory

Misra,

Gale

2019

Preprint

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“…Of course new phenomena do arise from thermal effects. Many of them have been studied earlier in [13,14,15,16,18,20,21,22]. In the following section, we will study another interesting thermal effect, the bulk viscosity.…”

Section: Towards Bulk Viscosity From the Gravity Dualmentioning

confidence: 99%

“…In the gauge theory side the full UV completion requires us to insert M anti-D5 branes in a set-up with N D3 and M D5 branes located at the south pole of a resolved sphere [13,14,17]. The anti-D5 branes are separated from the D3/D5 branes and distributed on the upper half of the resolved sphere (see figure 1 in [18]). A natural question is then of the stability of the system against annihilation.…”

Section: Introduction and A Brief Review Of The Modelmentioning

confidence: 99%

“…This is the set-up where many of the thermal QCD calculations may now be performed. For example melting of the quarkonium states [15,21], QGP dynamics [20], effect of a chemical potential [16], energy loss of a moving quark [13], transport coefficients including viscosity and entropy of the system [13,20,22], vector and scalar mesonic states [18] and renormalization group flow, among other things 2 . The latter is discussed briefly in [16] and [17] and in section 3 we present a more detailed study.…”

Section: Introduction and A Brief Review Of The Modelmentioning

confidence: 99%

“…This implies no change in the analysis as emphasized above. 18 This further implies that the r integral would run from r h to r c , the cut-off radius. This cut-off radius r c is similar to the cut-off radius r c that we encountered in section 3.…”

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Renormalization group flow, stability, and bulk viscosity in a large N thermal QCD model

et al. 2017

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The ultraviolet completion of a large N QCD model requires introducing new degrees of freedom at certain scale so that the UV behavior may become asymptotically conformal with no Landau poles and no UV divergences of Wilson loops. These UV degrees of freedom are represented by certain anti-branes arranged on the blown-up sphere of a warped resolved conifold in a way that they are separated from the other set of branes that control the IR behavior of the theory. This separation of the branes and the anti-branes creates instability in the theory. Further complications arise from the curvature of the ambient space. We show that, despite these analytical hurdles, stability may still be achieved by switching on appropriate world-volume fluxes on the branes. The UV degrees of freedom, on the other hand, modify the RG flow in the model. We discuss this in details by evaluating the flow from IR confining to UV conformal. Finally we lay down a calculational scheme to study bulk viscosity which, in turn, would signal the inherent non-conformality in this model.

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Bulk viscosity at extreme limits: from kinetic theory to strings

Czajka

Dasgupta

Gale

et al. 2019

J. High Energ. Phys.

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In this paper we study bulk viscosity in a thermal QCD model with large number of colors at two extreme limits: the very weak and the very strong 't Hooft couplings. The weak coupling scenario is based on kinetic theory, and one may go to the very strong coupling dynamics via an intermediate coupling regime. Although the former has a clear description in terms of kinetic theory, the intermediate coupling regime, which uses lattice results, suffers from usual technical challenges that render an explicit determination of bulk viscosity somewhat difficult. On the other hand, the very strong 't Hooft coupling dynamics may be studied using string theories at both weak and strong string couplings using gravity duals in type IIB as well as M-theory respectively. In type IIB we provide the precise fluctuation modes of the metric in the gravity dual responsible for bulk viscosity, compute the speed of sound in the medium and analyze the ratio of the bulk to shear viscosities. In M-theory, where we uplift the type IIA mirror dual of the UV complete type IIB model, we study and compare both the bulk viscosity and the sound speed by analyzing the quasi-normal modes in the system at strong IIA string coupling. By deriving the spectral function, we show the consistency of our results both for the actual values of the parameters involved as well for the bound on the ratio of bulk to shear viscosities. 65 5.1 The mirror type IIA model and its M-theory uplift 66 5.2 Quasi-normal modes, attenuation constant and the sound speed 70 5.3 The case with a vanishing bare resolution parameter 76 5.4 Shear viscosity, entropy and the bulk viscosity bound 80 6. Type IIA spectral function and the viscosity bound at strong coupling with non-zero flavors 85 6.1 Background gauge fluxes and perturbations on the flavor branes 86 6.2 Equation of motion for gauge field fluctuations 88 6.3 On-shell action and the strong coupling spectral function 95 6.4 The strong string coupling limit and pure classical supergravity 103 -1 -7. Conclusions and discussions 107 A. A Gauge-Invariant Combination of Scalar Modes of Metric Perturbations 112 A.1 The equation of motion for the fluctuation mode H tt 113 A.2 The equation of motion for the combined mode H s 115 A.3 The equations of motion for the remaining fluctuation modes 116 B. A derivation of the on-shell action and the Green's function 118C. Effective number of three-brane charges with background threeforms and the horizon radius 1201 Violation of this bound is seen in the presence of higher derivative terms, discussed first in [23]. In the absence of these terms, the KSS [22] bound continues to hold at strong 't Hooft coupling.2 The non-conformal string theory studied in [30] is different from what we consider here. In [30] it's the N = 2 * supersymmetric gauge theory obtained by a mass deformation of N = 4 Super Yang Mills theory. See also [31] and [32] for an even earlier study on bulk viscosity from first principles.

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Infrared Dynamics of a Large N QCD Model, the Massless String Sector and Mesonic Spectra

Cited by 4 publications

References 0 publications

The QCD Trace Anomaly at Strong Coupling from M-Theory

The QCD Trace Anomaly at Strong Coupling from M-Theory

Renormalization group flow, stability, and bulk viscosity in a large N thermal QCD model

Bulk viscosity at extreme limits: from kinetic theory to strings

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