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Power Law of Shear Viscosity in Einstein-Maxwell-Dilaton-Axion model

Yi Ling; Zhuoyu Xian; Zhenhua ZhouSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We construct charged black hole solutions with hyperscaling violation in the infrared(IR) region in Einstein-Maxwell-Dilaton-Axion theory and investigate the temperature behavior of the ratio of holographic shear viscosity to the entropy density. When translational symmetry breaking is relevant in the IR, the power law of the ratio is testi ed numerically at low temperature T, namely, =s T , where the values of exponent coincide with the analytical results. We also nd that the exponent is not a ected by irrelevant current, but is reduced by the relevant current. |

Holographic incoherent transport in Einstein-Maxwell-Dilaton Gravity

Zhenhua Zhou; Yi Ling; Jian-Pin WuSubjects: Physics >> Nuclear Physics

Recent progress in holographic approach makes it more transparent that each conductivity can be decomposed into the coherent contribution due to momentum relaxation and the incoherent contribution due to intrinsic current relaxation. In this paper we investigate this decomposition in the framework of Einstein-Maxwell-Dilaton theory. We derive the perturbation equations which are decoupled for a large class of background solutions, and then obtain the analytic results of conductivity with slow momentum relaxation in low frequency approximation, which is consistent with the known results from memory matrix techniques. |

DC and Hall conductivity in holographic massive Einstein-Maxwell-Dilaton gravity

Zhenhua Zhou; Jian-Pin Wu; Yi LingSubjects: Physics >> Nuclear Physics

We investigate the holographic DC and Hall conductivity in massive Einstein-Maxwell-Dilaton (EMD) gravity. Two special EMD backgrounds are considered explicitly. One is dyonic Reissner-Nordstro╩-AdS (RN-AdS) geometry and the other one is hyperscaling violation AdS (HV-AdS) geometry. We find that the linear-T resistivity and quadratic-T inverse Hall angle can be simultaneously achieved in HV-AdS models, providing a hint to construct holographic models confronting with the experimental data of strange metal in future. |

Holographic Metal-Insulator Transition in Higher Derivative Gravity

Yi Ling; Peng Liu; Jian-Pin Wu; Zhenhua ZhouSubjects: Physics >> Nuclear Physics

We introduce a Weyl term into the Einstein-Maxwell-Axion theory in four dimensional spacetime. Up to the first order of the Weyl coupling parameter?γ, we construct charged black brane solutions without translational invariance in a perturbative manner. Among all the holographic frameworks involving higher derivative gravity, we are the first to obtain metal-insulator transitions (MIT) when varying the system parameters at zero temperature. Furthermore, we study the holographic entanglement entropy (HEE) of strip geometry in this model and find that the second order derivative of HEE with respect to the axion parameter exhibits maximization behavior near quantum critical points (QCPs) of MIT. It testifies the conjecture in?1502.03661?and?1604.04857?that HEE itself or its derivatives can be used to diagnose quantum phase transition (QPT). |

Holographic Shear Viscosity in Hyperscaling Violating Theories without Translational Invariance

Yi Ling; Zhuoyu Xian; Zhenhua ZhouSubjects: Physics >> Nuclear Physics

In this paper we investigate the ratio of shear viscosity to entropy density,?η/s, in hyperscaling violating geometry with lattice structure. We show that the scaling relation with hyperscaling violation gives a strong constraint to the mass of graviton and usually leads to a power law of temperature,?η/s?Tκ. Remarkably, we find the exponent?κ?can be greater than two such that the new bound for viscosity raised inarXiv:1601.02757?is violated. Our above observation is testified by constructing specific solutions with UV completion in various holographic models. Finally, we compare the boundedness of?κ?with the behavior of entanglement entropy and conjecture a relation between them. |

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