7,448 research outputs found
Holographic Butterfly Effect at Quantum Critical Points
When the Lyapunov exponent in a quantum chaotic system saturates
the bound , it is proposed that this system has a
holographic dual described by a gravity theory. In particular, the butterfly
effect as a prominent phenomenon of chaos can ubiquitously exist in a black
hole system characterized by a shockwave solution near the horizon. In this
paper we propose that the butterfly velocity can be used to diagnose quantum
phase transition (QPT) in holographic theories. We provide evidences for this
proposal with an anisotropic holographic model exhibiting metal-insulator
transitions (MIT), in which the derivatives of the butterfly velocity with
respect to system parameters characterizes quantum critical points (QCP) with
local extremes in zero temperature limit. We also point out that this proposal
can be tested by experiments in the light of recent progress on the measurement
of out-of-time-order correlation function (OTOC).Comment: 7 figures, 15 page
Lattice calculation of hadronic tensor of the nucleon
We report an attempt to calculate the deep inelastic scattering structure
functions from the hadronic tensor calculated on the lattice. We used the
Backus-Gilbert reconstruction method to address the inverse Laplace
transformation for the analytic continuation from the Euclidean to the
Minkowski space.Comment: 8 pages, 5 figures; Proceedings of the 35th International Symposium
on Lattice Field Theory, 18-24 June 2017, Granada, Spai
Variance Reduction and Cluster Decomposition
It is a common problem in lattice QCD calculation of the mass of the hadron
with an annihilation channel that the signal falls off in time while the noise
remains constant. In addition, the disconnected insertion calculation of the
three-point function and the calculation of the neutron electric dipole moment
with the term suffer from a noise problem due to the
fluctuation. We identify these problems to have the same origin and the
problem can be overcome by utilizing the cluster decomposition
principle. We demonstrate this by considering the calculations of the glueball
mass, the strangeness content in the nucleon, and the CP violation angle in the
nucleon due to the term. It is found that for lattices with physical
sizes of 4.5 - 5.5 fm, the statistical errors of these quantities can be
reduced by a factor of 3 to 4. The systematic errors can be estimated from the
Akaike information criterion. For the strangeness content, we find that the
systematic error is of the same size as that of the statistical one when the
cluster decomposition principle is utilized. This results in a 2 to 3 times
reduction in the overall error.Comment: 7 pages, 5 figures, appendix added to address the systematic erro
Holographic Metal-Insulator Transition in Higher Derivative Gravity
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
, 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).Comment: 20 pages, 4 figures; typo corrected, added 3 references; minor
revisio
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