AdS/CFT correspondence

About: AdS/CFT correspondence is a research topic. Over the lifetime, 6660 publications have been published within this topic receiving 355520 citations.

Dynamical gap and cupratelike physics from holography

Abstract: We study the properties of fermion correlators in a boundary theory dual to the Reissner-Nordstr\"om ${\mathrm{AdS}}_{d+1}$ background in the presence of a bulk dipole (Pauli) interaction term with strength $p$. We show that by simply changing the value of the parameter $p$ we can tune continuously from a Fermi liquid (small $p$), to a marginal-Fermi liquid behavior at a critical value of $p$, to a generic non-Fermi liquid at intermediate values of $p$, and finally to a Mott insulator at large values of the bulk Pauli coupling. As all of these phases are seen in the cuprate phase diagram, the holographic model we study has the key elements of the strong-coupling physics typified by Mott systems. In addition, we extend our analysis to finite temperature and show that the Mott gap closes. Of particular interest is that it closes when the ratio of the gap to the critical temperature is of the order of 10. This behavior is very much similar to that observed in the classic Mott insulator ${\mathrm{VO}}_{2}$. We then analyze the nonanalyticities of the boundary theory fermion correlators for generic values of frequency and momentum by calculating the quasinormal modes of the bulk fermions. Not surprisingly, we find no evidence for the dipole interaction inducing an instability in the boundary theory. Finally, we briefly consider the introduction of superconducting condensates and find that, in that case, the fermion gap is driven by scalar-fermion couplings rather than by the Pauli coupling.

On CFT and quantum chaos

Abstract: We make three observations that help clarify the relation between CFT and quantum chaos. We show that any 1+1-D system in which conformal symmetry is non-linearly realized exhibits two main characteristics of chaos: maximal Lyapunov behavior and a spectrum of Ruelle resonances. We use this insight to identify a lattice model for quantum chaos, built from parafermionic spin variables with an equation of motion given by a Y-system. Finally we point to a relation between the spectrum of Ruelle resonances of a CFT and the analytic properties of OPE coefficients between light and heavy operators. In our model, this spectrum agrees with the quasi-normal modes of the BTZ black hole.

On entanglement entropy functionals in higher-derivative gravity theories

Abstract: In arXiv:1310.5713 [1] and arXiv:1310.6659 [2] a formula was proposed as the entanglement entropy functional for a general higher-derivative theory of gravity, whose lagrangian consists of terms containing contractions of the Riemann tensor. In this paper, we carry out some tests of this proposal. First, we find the surface equation of motion for general four-derivative gravity theory by minimizing the holographic entanglement entropy functional resulting from this proposed formula. Then we calculate the surface equation for the same theory using the generalized gravitational entropy method of arXiv:1304.4926 [3]. We find that the two do not match in their entirety. We also construct the holographic entropy functional for quasi-topological gravity, which is a six-derivative gravity theory. We find that this functional gives the correct universal terms. However, as in the R2 case, the generalized gravitational entropy method applied to this theory does not give exactly the surface equation of motion coming from minimizing the entropy functional.

Holographic thermalization with Lifshitz scaling and hyperscaling violation

Abstract: A Vaidya type geometry describing gravitation collapse in asymptotically Lifshitz spacetime with hyperscaling violation provides a simple holographic model for thermalization near a quantum critical point with non-trivial dynamic and hyperscaling violation exponents. The allowed parameter regions are constrained by requiring that the matter energy momentum tensor satisfies the null energy condition. We present a combination of analytic and numerical results on the time evolution of holographic entanglement entropy in such backgrounds for different shaped boundary regions and study various scaling regimes, generalizing previous work by Liu and Suh.