This section is devoted to more dynamical applications of brane effective actions. More specifically, I will describe some well-established reinterpretations of certain brane probe calculations in the context of the AdS/CFT correspondence [366, 269, 498, 13]. I will mainly focus on two aspects:

- The use of classical solitons solving the brane (string) equations of motion in particular backgrounds and with specific boundary conditions, to holographically compute either the expectation value of certain gauge invariant operators or the spectrum in sectors of certain strongly coupled gauge theories.
- The use of D-brane effective actions to describe the dynamics of a small number of degrees of freedom responsible either for deforming the original dual CFT to theories with less or no supersymmetry, or for capturing the interaction of massless modes among themselves and with other sectors of the system conveniently replaced by a supergravity background.

Covariance of brane effective actions allows one to couple them to any on-shell supergravity background.
In particular, one can probe either AdS_{5} × S^{5}, or black holes with these asymptotics, with branes, and
according to the AdS/CFT correspondence, one will be studying properties of the strongly coupled
holographic theory in the vacuum or at finite temperature and chemical potentials, respectively. This
set-up is illustrated in Figure 8. The same interpretation will hold for non-relativistic versions
of these backgrounds. Alternatively, and depending on the boundary conditions imposed on
these probes, they can deform the theory towards less symmetric and more realistic physical
systems.

In the following, I will review the calculation of Wilson loop expectation values, the use of worldsheet string solitons to study the spectrum of states with large charges in SYM and the use of D-brane probes to either add flavour to the AdS/CFT correspondence or describe the dynamics of massless excitations in non-relativistic (thermal) set-ups, which could be of relevance for strongly-coupled condensed-matter physics.

6.1 Wilson loops

6.2 Quark energy loss in a thermal medium

6.3 Semiclassical correspondence

6.4 Probes as deformations and gapless excitations in complex systems

6.2 Quark energy loss in a thermal medium

6.3 Semiclassical correspondence

6.4 Probes as deformations and gapless excitations in complex systems

Living Rev. Relativity 15, (2012), 3
http://www.livingreviews.org/lrr-2012-3 |
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