15,135 research outputs found
Simplified topological invariants for interacting insulators
We propose general topological order parameters for interacting insulators in
terms of the Green's function at zero frequency. They provide an unified
description of various interacting topological insulators including the quantum
anomalous Hall insulators and the time reversal invariant insulators in four,
three and two dimensions. Since only Green's function at zero frequency is
used, these topological order parameters can be evaluated efficiently by most
numerical and analytical algorithms for strongly interacting systems.Comment: Published versio
Nucleation of membrane adhesions
Recent experimental and theoretical studies of biomimetic membrane adhesions [Bruinsma et al., Phys. Rev. E 61, 4253 (2000); Boulbitch et al., Biophys. J. 81, 2743 (2001)] suggested that adhesion mediated by receptor interactions is due to the interplay between membrane undulations and a double-well adhesion potential, and should be a first-order transition. We study the nucleation of membrane adhesion by finding the minimum-energy path on the free energy surface constructed from the bending free energy of the membrane and the double-well adhesion potential. We find a nucleation free energy barrier around 20kBT for adhesion of flexible membranes, which corresponds to fast nucleation kinetics with a time scale of the order of seconds. For cell membranes with a larger bending rigidity due to the actin network, the nucleation barrier is higher and may require active processes such as the reorganization of the cortex network to overcome this barrier. Our scaling analysis suggests that the geometry of the membrane shapes of the adhesion contact is controlled by the adhesion length that is determined by the membrane rigidity, the barrier height, and the length scale of the double-well potential, while the energetics of adhesion is determined by the depths of the adhesion potential. These results are verified by numerical calculations
Effect of Earth's rotation on the trajectories of free-fall bodies in Equivalence Principle Experiment
Owing to Earth's rotation a free-fall body would move in an elliptical orbit
rather than along a straight line forward to the center of the Earth. In this
paper on the basis of the theory for spin-spin coupling between macroscopic
rotating bodies we study violation of the equivalence principle from
long-distance free-fall experiments by means of a rotating ball and a
non-rotating sell. For the free-fall time of 40 seconds, the difference between
the orbits of the two free-fall bodies is of the order of 10^{-9}cm which could
be detected by a SQUID magnetometer owing to such a magnetometer can be used to
measure displacements as small as 10^{-13} centimeters.Comment: 6 pages, 4 figure
Convergence on Gauss-Seidel iterative methods for linear systems with general H-matrices
It is well known that as a famous type of iterative methods in numerical
linear algebra, Gauss-Seidel iterative methods are convergent for linear
systems with strictly or irreducibly diagonally dominant matrices, invertible
matrices (generalized strictly diagonally dominant matrices) and Hermitian
positive definite matrices. But, the same is not necessarily true for linear
systems with nonstrictly diagonally dominant matrices and general matrices.
This paper firstly proposes some necessary and sufficient conditions for
convergence on Gauss-Seidel iterative methods to establish several new
theoretical results on linear systems with nonstrictly diagonally dominant
matrices and general matrices. Then, the convergence results on
preconditioned Gauss-Seidel (PGS) iterative methods for general matrices
are presented. Finally, some numerical examples are given to demonstrate the
results obtained in this paper
Multiple scattering effects on heavy meson production in p+A collisions at backward rapidity
We study the incoherent multiple scattering effects on heavy meson production
in the backward rapidity region of p+A collisions within the generalized
high-twist factorization formalism. We calculate explicitly the double
scattering contributions to the heavy meson differential cross sections by
taking into account both initial-state and final-state interactions, and find
that these corrections are positive. We further evaluate the nuclear
modification factor for muons that come form the semi-leptonic decays of heavy
flavor mesons. Phenomenological applications in d+Au collisions at a
center-of-mass energy GeV at RHIC and in p+Pb collisions at
TeV at the LHC are presented. We find that incoherent multiple
scattering can describe rather well the observed nuclear enhancement in the
intermediate region for such reactions.Comment: 10 pages, 6 figures, published version in PL
Equivalent topological invariants of topological insulators
A time-reversal invariant topological insulator can be generally defined by
the effective topological field theory with a quantized \theta coefficient,
which can only take values of 0 or \pi. This theory is generally valid for an
arbitrarily interacting system and the quantization of the \theta invariant can
be directly measured experimentally. Reduced to the case of a non-interacting
system, the \theta invariant can be expressed as an integral over the entire
three dimensional Brillouin zone. Alternatively, non-interacting insulators can
be classified by topological invariants defined over discrete time-reversal
invariant momenta. In this paper, we show the complete equivalence between the
integral and the discrete invariants of the topological insulator.Comment: Published version. Typos correcte
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