95 research outputs found
Magnetoconductivity in chiral Lifshitz hydrodynamics
In this paper, based on the principles of linear response theory, we compute
the longitudinal DC conductivity associated with Lifshitz like fixed points in
the presence of chiral anomalies in () dimensions. In our analysis,
apart from having the usual anomalous contributions due to chiral anomaly, we
observe an additional and pure \textit{parity odd} effect to the
magnetoconductivity which has its origin in the broken Lorentz (boost)
invariance at a Lifshitz fixed point. We also device a holographic set up in
order to compute () Lifshitz contributions to the magnetoconductivity
precisely at strong coupling and low charge density limit.Comment: Minor clarifications added, Version To Appear In JHE
Holographic Butterfly Effect and Diffusion in Quantum Critical Region
We investigate the butterfly effect and charge diffusion near the quantum
phase transition in holographic approach. We argue that their criticality is
controlled by the holographic scaling geometry with deformations induced by a
relevant operator at finite temperature. Specifically, in the quantum critical
region controlled by a single fixed point, the butterfly velocity decreases
when deviating from the critical point. While, in the non-critical region, the
behavior of the butterfly velocity depends on the specific phase at low
temperature. Moreover, in the holographic Berezinskii-Kosterlitz-Thouless
transition, the universal behavior of the butterfly velocity is absent.
Finally, the tendency of our holographic results matches with the numerical
results of Bose-Hubbard model. A comparison between our result and that in the
nonlinear sigma model is also given.Comment: 41 pages, 7 figures, minor revisions, refs adde
Black Hole Thermodynamics and Heavy Fermion Metals
Heavy fermion alloys at critical doping typically exhibit non-Fermi-liquid
behavior at low temperatures, including a logarithmic or power law rise in the
ratio of specific heat to temperature as the temperature is lowered. Anomalous
specific heat of this type is also observed in a simple class of gravitational
dual models that exhibit anisotropic scaling with dynamical critical exponent z
> 1.Comment: 17 pages, 4 figures; v2: added references; v3: matches published
versio
Dressing the Electron Star in a Holographic Superconductor
We construct new asymptotically AdS_4 solutions dual to 2+1 CFTs at finite
density and zero temperature by combining the ingredients of the electron star
and the holographic superconductor. The solutions, which we call "compact
electron stars", contain both a fermionic fluid and charged scalar hair in the
bulk. We show that the new solutions are thermodynamically favoured in the
region of parameter space where they exist. Along the boundary of this region,
we find evidence for a continuous phase transition between the holographic
superconductor and the compact star solution.Comment: 31 pages, 10 figures; added reference
DC Conductivities from Non-Relativistic Scaling Geometries with Momentum Dissipation
We consider a gravitational theory with two Maxwell fields, a dilatonic
scalar and spatially dependent axions. Black brane solutions to this theory are
Lifshitz-like and violate hyperscaling. Working with electrically charged
solutions, we calculate analytically the holographic DC conductivities when
both gauge fields are allowed to fluctuate. We discuss some of the subtleties
associated with relating the horizon to the boundary data, focusing on the role
of Lifshitz asymptotics and the presence of multiple gauge fields. The axionic
scalars lead to momentum dissipation in the dual holographic theory. Finally,
we examine the behavior of the DC conductivities as a function of temperature,
and comment on the cases in which one can obtain a linear resistivity.Comment: 32 pages, 3 figures. Figures and references added. Discussion
modifie
Dissipative superfluid dynamics from gravity
Charged asymptotically AdS black branes in five dimensions are sometimes
unstable to the condensation of charged scalar fields. For fields of infinite
charge and squared mass -4 Herzog was able to analytically determine the phase
transition temperature and compute the endpoint of this instability in the
neighborhood of the phase transition. We generalize Herzog's construction by
perturbing away from infinite charge in an expansion in inverse charge and use
the solutions so obtained as input for the fluid gravity map. Our tube wise
construction of patched up locally hairy black brane solutions yields a one to
one map from the space of solutions of superfluid dynamics to the long
wavelength solutions of the Einstein Maxwell system. We obtain explicit
expressions for the metric, gauge field and scalar field dual to an arbitrary
superfluid flow at first order in the derivative expansion. Our construction
allows us to read off the the leading dissipative corrections to the perfect
superfluid stress tensor, current and Josephson equations. A general framework
for dissipative superfluid dynamics was worked out by Landau and Lifshitz for
zero superfluid velocity and generalized to nonzero fluid velocity by Clark and
Putterman. Our gravitational results do not fit into the 13 parameter
Clark-Putterman framework. Purely within fluid dynamics we present a consistent
new generalization of Clark and Putterman's equations to a set of superfluid
equations parameterized by 14 dissipative parameters. The results of our
gravitational calculation fit perfectly into this enlarged framework. In
particular we compute all the dissipative constants for the gravitational
superfluid.Comment: v1: 58 + 1 pages; v2: 83 + 1 page
Parity Breaking Transport in Lifshitz Hydrodynamics
We derive the constitutive relations of first order charged hydrodynamics for
theories with Lifshitz scaling and broken parity in and spacetime
dimensions. In addition to the anomalous (in ) or Hall (in )
transport of relativistic hydrodynamics, there is an additional non-dissipative
transport allowed by the absence of boost invariance. We analyze the
non-relativistic limit and use a phenomenological model of a strange metal to
argue that these effects can be measured in principle by using electromagnetic
fields with non-zero gradients.Comment: Corrected Appendix A1. Revised the end of subsection 2.1, added the
case z \neq
- …