[Paper Review] The Limits of Gauge-Gravity Duality

Brett McInnes|arXiv (Cornell University)|Mar 13, 2014

High-Energy Particle Collisions Research74 references8 citations

TL;DR

This paper investigates the limitations of gauge-gravity duality in describing the quark-gluon plasma (QGP), particularly at large chemical potentials. It argues that while the duality breaks down at extremely high temperatures due to stringy effects, it also faces a bound on applicability at high chemical potentials—a bound that can be significantly influenced by angular momentum, potentially making it testable in future experiments with rapidly rotating QGP states.

ABSTRACT

The Quark-Gluon Plasma [QGP] is described in terms of gauge-gravity duality by charged, locally asymptotically AdS black holes. This duality cannot however be expected to account for an arbitrarily large domain in the quark-matter phase diagram: one does not for example expect that it will provide a good description at extremely high temperatures [where a fully stringy account of the bulk will be necessary]. We argue that, likewise, the gauge-gravity duality itself points to a bound on its applicability in the direction of large chemical potentials, though in most cases at values far beyond experimental access. However, the upper bound can, in some circumstances, depend strongly on the amount of angular momentum present, and it is conceivable that this bound could be probed by experiments designed to produce rapidly rotating quark-gluon plasmas with large chemical potentials.

Motivation & Objective

• To examine the theoretical boundaries of gauge-gravity duality in describing the quark-gluon plasma (QGP).
• To identify constraints on the applicability of the duality in regions of large chemical potential.
• To investigate how angular momentum influences the upper bound on chemical potential where the duality remains valid.
• To assess the potential for experimental probing of these bounds via rapidly rotating QGP states.

Proposed method

• Uses charged, locally asymptotically AdS black holes as gravitational duals to model the QGP.
• Analyzes the behavior of the gauge-gravity duality framework under increasing chemical potential.
• Evaluates the role of angular momentum in modifying the upper bound for chemical potential validity.
• Applies known results from string theory and black hole thermodynamics to infer constraints on the dual field theory.
• Compares the regime of validity of the duality to known high-energy limits where stringy effects dominate.
• Considers the implications for experimental design, particularly in scenarios involving rotating QGP.

Experimental results

Research questions

• RQ1 At what chemical potential does gauge-gravity duality cease to provide a reliable description of the QGP?
• RQ2 How does angular momentum in the QGP affect the upper bound of chemical potential for which the duality remains applicable?
• RQ3 Can the theoretical bounds on chemical potential be probed experimentally through rapidly rotating quark-gluon plasmas?
• RQ4 What are the implications of these bounds for the validity of the gauge-gravity duality in the full quark-matter phase diagram?
• RQ5 How do the constraints from high-temperature stringy effects compare to those from large chemical potentials?

Key findings

• The gauge-gravity duality is expected to break down at extremely high temperatures due to the necessity of a fully stringy description of the bulk.
• A bound on the applicability of the duality exists in the direction of large chemical potentials, though it typically lies far beyond current experimental reach.
• The upper bound on chemical potential can be strongly influenced by the presence of angular momentum in the system.
• In some cases, the bound may be low enough to be accessible to future experiments producing rapidly rotating quark-gluon plasmas.
• The duality's validity is thus constrained not only by temperature but also by chemical potential and angular momentum, with the latter offering a potential experimental probe.