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arXiv · 2507.13497

Out-of-bounds hydrodynamics in holographic anisotropic Dirac semimetals

Sebastián Bahamondes·Ignacio Salazar Landea·Rodrigo Soto-Garrido
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Abstract

We present a version of a strongly correlated 2+1-dimensional condensed matter system that features a thermal phase transition between a semimetal and an insulator through a semi-Dirac quantum critical region using AdS/CFT holography. We introduce backreaction into the bulk equations of motion to measure transport coefficients in the boundary; specifically the shear viscosity $\eta$. By explicitly breaking rotational symmetry we find a new instance of violation of the KSS-bound for the $\eta/s$ ratio in the quantum critical region, as well as a monotone dependence on temperature in the $T\to 0$ regime fixed by a Lifshitz dynamical critical exponent. We find that the Lifshitz critical exponent in the anisotropic direction is approximately equal to $2$ for our choice of backreaction parameters. We find explicit $T=0$ solutions separated by a quantum critical point in parameter space, showing that the thermal critical phase found in previous work comes from a quantum phase transition at zero temperature.

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Sebastián Bahamondes, Ignacio Salazar Landea, Rodrigo Soto-Garrido. 2025-07-17. Out-of-bounds hydrodynamics in holographic anisotropic Dirac semimetals. https://arxiv.org/abs/2507.13497

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