Improved Holographic QCD and the Quark--Gluon Plasma

Gürsoy, Umut

doi:10.5506/aphyspolb.47.2509

Cited by 9 publications

(7 citation statements)

References 118 publications

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“…From a general point of view, we note that despite the fact that the holographic model considered in this article is one of the most realistic holographic approaches available for QCD -that compares well with QCD data in the various sectors [115,116] -there is room for improvement. For applications at finite magnetic field, it would be important to implement up and down type quarks in the model, so that the magnetic field would couple to the physical charge rather than baryon number.…”

Section: Jhep03(2021)180mentioning

confidence: 99%

On the interplay between magnetic field and anisotropy in holographic QCD

Gürsoy

Järvinen

Nijs

et al. 2021

J. High Energ. Phys.

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We investigate the combined effects of anisotropy and a magnetic field in strongly interacting gauge theories by the gauge/gravity correspondence. Our main motivation is the quark-gluon plasma produced in off-central heavy-ion collisions which exhibits large anisotropy in pressure gradients as well as large external magnetic fields. We explore two different configurations, with the anisotropy either parallel or perpendicular to the magnetic field, focusing on the competition and interplay between the two. A detailed study of the RG flow in the ground state reveals a rich structure where depending on which of the two, anisotropy or magnetic field, is stronger, intermediate geometries with approximate AdS4 × ℝ and AdS3 × ℝ2 factors arise. This competition is also manifest in the phase structure at finite temperature, specifically in the dependence of the chiral transition temperature on anisotropy and magnetic field, from which we infer the presence of inverse magnetic and anisotropic catalyses of the chiral condensate. Finally, we consider other salient observables in the theory, including the quark-antiquark potential, shear viscosity, entanglement entropy and the butterfly velocity. We demonstrate that they serve as good probes of the theory, in particular, distinguishing between the effects of the magnetic field and anisotropy in the ground and plasma states. We also find that the butterfly velocity, which codifies how fast information propagates in the plasma, exhibits a rich structure as a function of temperature, anisotropy and magnetic field, exceeding the conformal value in certain regimes.

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Section: Jhep03(2021)180mentioning

confidence: 99%

On the interplay between magnetic field and anisotropy in holographic QCD

Gürsoy

Järvinen

Nijs

et al. 2021

J. High Energ. Phys.

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“…where the subscript indicates a zero magnetic field and the superscript fc denotes the value at finite coupling 6 . Thus, holography correctly encodes the smallness of the Reynolds 3 Far more sophisticated models are available: see for example [22,23] and references therein. 4 See [25][26][27] for recent (non-holographic) theoretical perspectives on this question.…”

Section: Holographic Model Of ν(Qgp): Generalities and Resultsmentioning

confidence: 99%

Holography of the QGP Reynolds number

McInnes

2017

Nuclear Physics B

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The viscosity of the Quark-Gluon Plasma (QGP) is usually described holographically by the entropy-normalized dynamic viscosity η/s. However, other measures of viscosity, such as the kinematic viscosity ν and the Reynolds number Re, are often useful, and they too should be investigated from a holographic point of view. We show that a simple model of this kind puts an upper bound on Re for nearly central collisions at a given temperature; this upper bound is in very good agreement with the observational lower bound (from the RHIC facility). Furthermore, in a holographic approach using only Einstein gravity, η/s does not respond to variations of other physical parameters, while ν and Re can do so. In particular, it is known that the magnetic fields arising in peripheral heavy-ion collisions vary strongly with the impact parameter b, and we find that the holographic model predicts that ν and Re can also be expected to vary substantially with the magnetic field and therefore with b.

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“…I will discuss this in more detail in connection to the determination of the full V-QCD model below. For a more detailed account on the IHQCD part, see the reviews [229,236]. But before determining the model through comparison to data I review the general structure of the flavor sector.…”

Section: Improved Holographic Qcdmentioning

confidence: 99%

Holographic modeling of nuclear matter and neutron stars

Jarvinen

2021

Preprint

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I review holographic models for (dense and cold) nuclear matter, neutron stars, and their mergers. I start by a brief general discussion on current knowledge of cold QCD matter and neutron stars, and go on discussing various approaches to model cold nuclear and quark matter by using gauge/gravity duality, pointing out their strengths and weaknesses. Then I concentrate on recent results for a complex bottom-up holographic framework (V-QCD), which also takes input from lattice QCD results, effective field theory, and perturbative QCD. Dense nuclear matter is modeled in V-QCD through a homogeneous non-Abelian bulk gauge field. Feasible "hybrid" equations of state for cold nuclear (and quark) matter can be constructed by using traditional methods (e.g., effective field theory) at low densities and the holographic V-QCD model at higher densities. I discuss the constraints from this approach to the properties of the nuclear to quark matter transition as well as to properties of neutron stars. Using such hybrid equations of state as an input for numerical simulations of neutron star mergers, I also derive predictions for the spectrum of produced gravitational waves.

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Improved Holographic QCD and the Quark--Gluon Plasma

Cited by 9 publications

References 118 publications

On the interplay between magnetic field and anisotropy in holographic QCD

On the interplay between magnetic field and anisotropy in holographic QCD

Holography of the QGP Reynolds number

Holographic modeling of nuclear matter and neutron stars

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