paper

Thermal diffusivity and butterfly velocity in anisotropic Q-Lattice models

arXiv:1708.08822 · doi:10.1007/JHEP01(2018)140

Abstract

By using a holographic method we study a relation between the thermal diffusivity () and two quantum chaotic properties, Lyapunov time () and butterfly velocity () in strongly correlated systems. It has been shown that is universal in some holographic models as well as condensed matter systems including the Sachdev-Ye-Kitaev (SYK) models. We investigate to what extent this relation is universal in the Q-lattice models with infrared (IR) scaling geometry, focusing on the effect of spatial anisotropy. Indeed it was shown that () is determined only by some scaling exponents of the IR metric in the low temperature limit regardless of the matter fields and ultraviolet data. Inspired by this observation, in this work, we find the concrete expressions for in terms of the critical dynamical exponents in each direction. By analyzing the IR scaling geometry we identify the allowed scaling parameter regimes, which enable us to compute the allowed range of . We find the lower bound of is always , which is not affected by anisotropy, contrary to the case. However, there may be an upper bound determined by anisotropy.

32 pages, 1 figure, v2: 33 pages, references added

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