2,614 research outputs found
A Harmonic Extension Approach for Collaborative Ranking
We present a new perspective on graph-based methods for collaborative ranking
for recommender systems. Unlike user-based or item-based methods that compute a
weighted average of ratings given by the nearest neighbors, or low-rank
approximation methods using convex optimization and the nuclear norm, we
formulate matrix completion as a series of semi-supervised learning problems,
and propagate the known ratings to the missing ones on the user-user or
item-item graph globally. The semi-supervised learning problems are expressed
as Laplace-Beltrami equations on a manifold, or namely, harmonic extension, and
can be discretized by a point integral method. We show that our approach does
not impose a low-rank Euclidean subspace on the data points, but instead
minimizes the dimension of the underlying manifold. Our method, named LDM (low
dimensional manifold), turns out to be particularly effective in generating
rankings of items, showing decent computational efficiency and robust ranking
quality compared to state-of-the-art methods
Pole analysis on the hadron spectroscopy of
In this paper we study the spectroscopy in the process of
. The final state interactions of coupled channel
~-~ ~-~ are constructed
based on K-matrix with the Chew-Mandelstam function. We build the amplitude according to the Au-Morgan-Pennington method. The event
shape is fitted and the decay width of is used to
constrain the parameters, too. With the amplitudes we extract out the poles and
their residues. Our amplitude and pole analysis suggest that the
should be molecule, the could be an S-wave
compact pentaquark state, and the structure around is caused by the
cusp effect. The future experimental measurement of the decays of and would further
help to study the nature of these resonances.Comment: updated to the published versio
The possible tetraquark states observed by the LHCb experiment
We give a brief comment on the possible tetraquark states
observed by the LHCb experiment.Comment: Contribution to Science Bulletin as a NEWS & VIEWS Pape
Nonlinear optical properties of an electromagnetically-induced-transparency medium interacting with two quantized fields
ManuscriptWe study linear and nonlinear optical properties of electromagnetically induced transparency (EIT) medium interacting with two quantized laser fields for adiabatic EIT case. We show that EIT medium exhibits normal dispersion. Kerr and higher order nonlinear refractive-index coefficients are also calculated in a completely analytical form. It is indicated that EIT medium exhibits giant resonantly enhanced nonlinearities. We discuss the response of the EIT medium to nonclassical light fields and find that the polarization vanishes when the probe laser is initially in a nonclassical state of no single-photon coherence
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