204 research outputs found
Holographic DC Conductivity for a Power-law Maxwell Field
We consider a neutral and static black brane background with a probe
power-law Maxwell field. Via the membrane paradigm, an expression for the
holographic DC conductivity of the dual conserved current is obtained. We also
discuss the dependence of the DC conductivity on the temperature, charge
density and spatial components of the external field strength in the boundary
theory. Our results show that there might be more than one phase in the
boundary theory. Phase transitions could occur where the DC conductivity or its
derivatives are not continuous. Specifically, we find that one phase possesses
a charge-conjugation symmetric contribution, negative magneto-resistance and
Mott-like behavior.Comment: 19 pages, 11 figures. arXiv admin note: text overlap with
arXiv:1711.0329
Loop Corrections in Double Field Theory: Non-trivial Dilaton Potentials
It is believed that the invariance of the generalised diffeomorphisms
prevents any non-trivial dilaton potential from double field theory. It is
therefore difficult to include loop corrections in the formalism. We show that
by redefining a non-local dilaton field, under strong constraint which is
necessary to preserve the gauge invariance of double field theory, the theory
does permit non-constant dilaton potentials and loop corrections. If the fields
have dependence on only one single coordinate, the non-local dilaton is
identical to the ordinary one with an additive constant.Comment: V3, 11 pages, references added, typos corrected, version to appear in
JHE
Holographic DC Conductivity for Backreacted Nonlinear Electrodynamics with Momentum Dissipation
We consider a holographic model with the charge current dual to a general
nonlinear electrodynamics (NLED) field. Taking into account the backreaction of
the NLED field on the geometry and introducing axionic scalars to generate
momentum dissipation, we obtain expressions for DC conductivities with a finite
magnetic field. The properties of the in-plane resistance are examined in
several NLED models. For Maxwell-Chern-Simons electrodynamics, negative
magneto-resistance and Mott-like behavior could appear in some parameter space
region. Depending on the sign of the parameters, we expect the NLED models to
mimic some type of weak or strong interactions between electrons. In the latter
case, negative magneto-resistance and Mott-like behavior can be realized at low
temperatures. Moreover, the Mott insulator to metal transition induced by a
magnetic field is also observed at low temperatures.Comment: 28 pages, 31 figures. Added reference
Quantum gravity effects on compact star cores
Using the Tolman-Oppenheimer-Volkoff equation and the equation of state of
zero temperature ultra-relativistic Fermi gas based on generalized uncertainty
principle (GUP), the quantum gravitational effects on the cores of compact
stars are discussed. Our results show that varies with .
Quantum gravity plays an important role in the region , where
, is the Planck length and is a
dimensionless parameter accounting for quantum gravity effects. Furthermore,
near the center of compact stars, we find that the metric components are
and . All these effects are
different from those obtained from classical gravity. These results can be
applied to neutron stars or denser ones like quark stars. The observed masses
of neutron stars () indicate that can not exceed
, not as good as the upper bound from simple
electroweak consideration. This means that incorporating either quantum gravity
effects or nuclear interactions, one obtains almost the same mass limits of
neutron stars.Comment: 12 pages, 1 figure, added brief review on compact stars
configurations, abstract expanded, references added, typo corrected,
published versio
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