3,413 research outputs found
Holographic Complexity Growth Rate in Horndeski Theory
Based on the context of complexity = action (CA) conjecture, we calculate the
holographic complexity of AdS black holes with planar and spherical topologies
in Horndeski theory. We find that the rate of change of holographic complexity
for neutral AdS black holes saturates the Lloyd's bound. For charged black
holes, we find that there exists only one horizon and thus the corresponding
holographic complexity can't be expressed as the difference of some
thermodynamical potential between two horizons as that of Reissner-Nordstrom
AdS black hole in Einstein-Maxwell theory. However, the Lloyd's bound is not
violated for charged AdS black hole in Horndeski theory.Comment: 20 pages, 6 figures, references added, typos correcte
Helical Topological Edge States in a Quadrupole Phase
Topological electric quadrupole is a recently proposed concept that extends
the theory of electric polarization of crystals to higher orders. Such a
quadrupole phase supports topological states localized on both edges and
corners. In this work, we show that in a quadrupole phase of honeycomb lattice,
topological helical edge states and pseudo-spin-polarized corner states appear
by making use of a pseudo-spin degree of freedom related to point group
symmetry. Furthermore, we argue that a general condition for emergence of
helical edge states in a (pseudo-)spinful quadrupole phase is mirror or
time-reversal symmetry. Our results offers a way of generating topological
helical edge states without spin-orbital couplings
Phase diagram of Kondo-Heisenberg model on honeycomb lattice with geometrical frustration
We calculated the phase diagram of the Kondo-Heisenberg model on
two-dimensional honeycomb lattice with both nearest-neighbor and
next-nearest-neighbor antiferromagnetic spin exchanges, to investigate the
interplay between RKKY and Kondo interactions at presence of magnetic
frustration. Within a mean-field decoupling technology in slave-fermion
representation, we derived the zero-temperature phase diagram as a function of
Kondo coupling and frustration strength . The geometrical frustration
can destroy the magnetic order, driving the original antiferromagnetic (AF)
phase to non-magnetic valence bond state (VBS). In addition, we found two
distinct VBS. As is increased, a phase transition from AF to Kondo
paramagnetic (KP) phase occurs, without the intermediate phase coexisting AF
order with Kondo screening found in square lattice systems. In the KP phase,
the enhancement of frustration weakens the Kondo screening effect, resulting in
a phase transition from KP to VBS. We also found a process to recover the AF
order from VBS by increasing in a wide range of frustration strength. Our
work may provide deeper understanding for the phase transitions in
heavy-fermion materials, particularly for those exhibiting triangular
frustration
Extracting -wave scattering lengths from cusp effect in heavy quarkonium dipion transitions
Charge-exchange rescattering leads to a cusp
effect in the invariant mass spectrum of processes with
in the final state which can be used to measure -wave
scattering lengths. Employing a non-relativistic effective field theory, we
discuss the possibility of extracting the scattering lengths in heavy
quarkonium transitions. The transition
is studied in details. We discuss the
precision that can be reached in such an extraction for a certain number of
events.Comment: 15 pages, 7 figures, 1 tabl
The edge engineering of topological Bi(111) bilayer
A topological insulator is a novel quantum state, characterized by
symmetry-protected non-trivial edge/surface states. Our first-principle
simulations show the significant effects of the chemical decoration on edge
states of topological Bi(111) bilayer nanoribbon, which remove the trivial edge
state and recover the Dirac linear dispersion of topological edge state. By
comparing the edge states with and without chemical decoration, the Bi(111)
bilayer nanoribbon offers a simple system for assessing conductance fluctuation
of edge states. The chemical decoration can also modify the penetration depth
and the spin texture of edge states. A low-energy effective model is proposed
to explain the distinctive spin texture of Bi(111) bilayer nanoribbon, which
breaks the spin-momentum orthogonality along the armchair edge.Comment: 5 pages, 5 figure
Horndeski Gravity and the Violation of Reverse Isoperimetric Inequality
We consider Einstein-Horndeski-Maxwell gravity, together with a cosmological
constant and multiple Horndeski axions. We construct charged AdS planar black
holes in general dimensions where the Horndeski anxions span over the planar
directions. We analyse the thermodynamics and obtain the black hole volumes. We
show that the reverse isoperimetric inequality can be violated, implying that
these black holes can store information more efficiently than the Schwarzschild
black hole.Comment: Latex, 25 pages, 1 figure, references adde
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