104,523 research outputs found
Non-local Geometry inside Lifshitz Horizon
Based on the quantum renormalization group, we derive the bulk geometry that
emerges in the holographic dual of the fermionic U(N) vector model at a nonzero
charge density. The obstruction that prohibits the metallic state from being
smoothly deformable to the direct product state under the renormalization group
flow gives rise to a horizon at a finite radial coordinate in the bulk. The
region outside the horizon is described by the Lifshitz geometry with a
higher-spin hair determined by microscopic details of the boundary theory. On
the other hand, the interior of the horizon is not described by any Riemannian
manifold, as it exhibits an algebraic non-locality. The non-local structure
inside the horizon carries the information on the shape of the filled Fermi
sea.Comment: 20 page
Vortex-flow electromagnetic emission in stacked intrinsic Josephson junctions
We confirmed the existence of the collective transverse plasma modes excited
by the motion of the Josephson vortex lattice in stacked intrinsic Josephson
junctions of BiSrCaCuO by observing the multiple
subbranches in the Josephson-vortex-flow current-voltage characteristics. We
also observed the symptom of the microwave emission from the resonance between
the Josephson vortex lattice and the collective transverse plasma modes, which
provides the possibility of developing Josephson-vortex-flow electromagnetic
oscillators.Comment: 4 pages, 3 figure
Sparse logistic principal components analysis for binary data
We develop a new principal components analysis (PCA) type dimension reduction
method for binary data. Different from the standard PCA which is defined on the
observed data, the proposed PCA is defined on the logit transform of the
success probabilities of the binary observations. Sparsity is introduced to the
principal component (PC) loading vectors for enhanced interpretability and more
stable extraction of the principal components. Our sparse PCA is formulated as
solving an optimization problem with a criterion function motivated from a
penalized Bernoulli likelihood. A Majorization--Minimization algorithm is
developed to efficiently solve the optimization problem. The effectiveness of
the proposed sparse logistic PCA method is illustrated by application to a
single nucleotide polymorphism data set and a simulation study.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS327 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Bulk and edge quasihole tunneling amplitudes in the Laughlin state
The tunneling between the Laughlin state and its quasihole excitations are
studied by using the Jack polynomial. We find a universal analytical formula
for the tunneling amplitude, which can describe both bulk and edge quasihole
excitations. The asymptotic behavior of the tunneling amplitude reveals the
difference and the crossover between bulk and edge states. The effects of the
realistic coulomb interaction with a background-charge confinement potential
and disorder are also discussed. The stability of the tunneling amplitude
manifests the topological nature of fractional quantum Hall liquids.Comment: 9 pages, 1 figure
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