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Catalog of AdS black holes

The action for the pure AdSd+1_{d+1} gravity is

S=dd+1xg(R2Λ),Λ=d(d1)2L2,S=\int d^{d+1}x\sqrt{-g}\,(R-2\Lambda),\qquad \Lambda=-\frac{d(d-1)}{2L^2},

where Λ\Lambda is the cosmological constant, and LL is the AdS radius. The equations of motion are Einstein’s equations

Rμν12gμνR+Λgμν=0Rμν+dL2gμν=0R_{\mu\nu}-\frac{1}{2}g_{\mu\nu}R+\Lambda g_{\mu\nu}=0 \quad\Leftrightarrow\quad R_{\mu\nu}+\frac{d}{L^2}g_{\mu\nu}=0

AdS gravity with matter fields can be used to construct various holographic quantum matter.

A “minimal” holographic superconductor model includes gravity, a U(1)U(1) gauge field, and a charged scalar:

S=dd+1xg[116πG(R+d(d1)L2)14FμνFμνDΨ2m2Ψ2],S = \int d^{d+1}x\,\sqrt{-g}\left[ \frac{1}{16\pi G}\left(R+\frac{d(d-1)}{L^2}\right) -\frac{1}{4}F_{\mu\nu}F^{\mu\nu} -|D\Psi|^2-m^2|\Psi|^2 \right],

with Dμ=μiqAμD_\mu = \nabla_\mu - i q A_\mu. Below a critical temperature, the scalar can condense, spontaneously breaking the boundary U(1)U(1) symmetry and producing superconducting behavior.

To model charge density waves (CDW) and related orders (such as pair density waves, PDW), one needs to allow for solutions that spontaneously break translation invariance.