32,731 research outputs found
Complexity growth rates for AdS black holes in massive gravity and gravity
The "complexity = action" duality states that the quantum complexity is equal
to the action of the stationary AdS black holes within the Wheeler-DeWitt patch
at late time approximation. We compute the action growth rates of the neutral
and charged black holes in massive gravity and the neutral, charged and
Kerr-Newman black holes in gravity to test this conjecture. Besides, we
investigate the effects of the massive graviton terms, higher derivative terms
and the topology of the black hole horizon on the complexity growth rate.Comment: 11 pages, no figur
Topological invariants for holographic semimetals
We study the behavior of fermion spectral functions for the holographic
topological Weyl and nodal line semimetals. We calculate the topological
invariants from the Green functions of both holographic semimetals using the
topological Hamiltonian method, which calculates topological invariants of
strongly interacting systems from an effective Hamiltonian system with the same
topological structure. Nontrivial topological invariants for both systems have
been obtained and the presence of nontrivial topological invariants further
supports the topological nature of the holographic semimetals.Comment: 39 pages, 11 figures, 1 table; v2: match published versio
Topological nodal line semimetals in holography
We show a holographic model of a strongly coupled topological nodal line
semimetal (NLSM) and find that the NLSM phase could go through a quantum phase
transition to a topologically trivial state. The dual fermion spectral function
shows that there are multiple Fermi surfaces each of which is a closed nodal
loop in the NLSM phase. The topological structure in the bulk is induced by the
IR interplay between the dual mass operator and the operator that deforms the
topology of the Fermi surface. We propose a practical framework for building
various strongly coupled topological semimetals in holography, which indicates
that at strong coupling topologically nontrivial semimetal states generally
exist.Comment: 21 pages, 5 figures; v2: match published versio
Anti-Swarming: Structure and Dynamics of Repulsive Chemically Active Particles
Chemically active Brownian particles with surface catalytic reactions may
repel each other due to diffusiophoretic interactions in the reaction and
product concentration fields. The system behavior can be described by a
`chemical' coupling parameter that compares the strength of
diffusiophoretic repulsion to Brownian motion, and by a mapping to the
classical electrostatic One Component Plasma (OCP) system. When confined to a
constant-volume domain, Body-Centered Cubic crystals spontaneously form from
random initial configurations when the repulsion is strong enough to overcome
Brownian motion. Face-Centered Cubic crystals may also be stable. The `melting
point' of the `liquid-to-crystal transition' occurs at for
both BCC and FCC lattices
Anisotropic swim stress in active matter with nematic order
Active Brownian Particles (ABPs) transmit a swim pressure to the container boundaries, where is the drag coefficient,
is the swim diffusivity and is the uniform bulk number density
far from the container walls. In this work we extend the notion of the
isotropic swim pressure to the anisotropic tensorial swim stress
, which is related to the
anisotropic swim diffusivity . We demonstrate this
relationship with ABPs that achieve nematic orientational order via a bulk
external field. The anisotropic swim stress is obtained analytically for dilute
ABPs in both 2D and 3D systems, and the anisotropy is shown to grow
exponentially with the strength of the external field. We verify that the
normal component of the anisotropic swim stress applies a pressure
on a wall
with normal vector , and, through Brownian dynamics simulations,
this pressure is shown to be the force per unit area transmitted by the active
particles. Since ABPs have no friction with a wall, the difference between the
normal and tangential stress components -- the normal stress difference --
generates a net flow of ABPs along the wall, which is a generic property of
active matter systems
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