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Motion of photons in a background of gravitational wave

Zhe Chang; Chao-Guang Huang; Zhi-Chao ZhaoSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

The photon motion in a Michelson interferometer is re-analyzed in both geometrical optics and wave optics. The classical paths of the photons in the background of gravitational wave are derived from Fermat principle, which is the same as the null geodesics in general relativity. The deformed Maxwell equations and the wave equations of electric elds in the background of gravitational wave are presented in at-space approximation. Both methods show that the response of an interferometer depends on the frequency of a gravitational wave, however it is almost independent of the frequency of the mirror's vibrations. It implies that the vibrating mirror cannot mimic a gravitational wave very well. |

Note on the butterfly effect in holographic superconductor models

Yi Ling; Peng Liu; Jian-Pin WuSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

In this note we remark that the butterfly effect can be used to diagnose the phase transition of superconductivity in a holographic framework. Speci cally, we compute the butterfly velocity in a charged black hole background as well as anisotropic backgrounds with Q-lattice structure. In both cases we nd its derivative to the temperature is discontinuous at critical points. We also ropose that the butterfly velocity can signalize the occurrence of thermal phase transition in general holographic models. |

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). |

750 GeV diphoton excess confronted with a top-pion in the TTM model

Yu-Chen Guo; Chong-Xing Yue; Zhen-hua ZhaoSubjects: Physics >> Nuclear Physics

The latest LHC data suggest an intriguing excess at?mγγ=750?GeV which apparently requires an explanation from the beyond standard model physics. In this note we explore the possibility for this signal to arise from a top-pion in the Top Triangle Moose model which can be viewed as a dimensional-deconstruction version of the top-color assisted technicolor model. We demonstrate that the observed excess can be accommodated by and has important implications for this interesting model. |

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. |

Characterization of Quantum Phase Transition using Holographic Entanglement Entropy

Yi Ling; Peng Liu; Jian-Pin WuSubjects: Physics >> Nuclear Physics

The entanglement exhibits extremal or singular behavior near quantum critical points (QCPs) in many condensed matter models. These intriguing phenomena, however, still call for a widely accepted understanding. In this letter we study this issue in holographic framework. We investigate the connection between the holographic entanglement entropy (HEE) and the quantum phase transition (QPT) in a lattice-deformed Einstein-Maxwell-Dilaton theory. Novel backgrounds exhibiting metal-insulator transitions (MIT) have been constructed in which both metallic phase and insulating phase have vanishing entropy density in zero temperature limit. We find that the first order derivative of HEE with respect to lattice parameters exhibits extremal behavior near QCPs. We propose that it would be a universal feature that HEE or its derivatives with respect to system parameters can characterize QPT in a generic holographic system. Our work opens a window for understanding the relation between entanglement and the QPT from holographic perspective. |

Pseudo-gap phase and duality in a holographic fermionic system with dipole coupling on Q-lattice

Yi Ling(1; Peng Liu; Chao Niu; Jian-Pin Wu(2Subjects: Physics >> Nuclear Physics

We classify the different phases by the "pole-zero mechanism" for a holographic fermionic system which contains a dipole coupling with strength?p?on a Q-lattice background. A complete phase structure in?pspace can be depicted in terms of Fermi liquid, non-Fermi liquid, Mott phase and pseudo-gap phase. In particular, we find that in general the region of the pseudo-gap phase in?p?space is suppressed when the Q-lattice background is dual to a deep insulating phase, while for an anisotropic background, we have an anisotropic region for the pseudo-gap phase in?p?space as well. In addition, we find that the duality between zeros and poles always exists regardless of whether or not the model is isotropic. |

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