3,204 research outputs found
NETS: Extremely fast outlier detection from a data stream via set-based processing
This paper addresses the problem of efficiently detecting outliers from a data stream as old data points expire from and new data points enter the window incrementally. The proposed method is based on a newly discovered characteristic of a data stream that the change in the locations of data points in the data space is typically very insignificant. This observation has led to the finding that the existing distance-based outlier detection algorithms perform excessive unnecessary computations that are repetitive and/or canceling out the effects. Thus, in this paper, we propose a novel set-based approach to detecting outliers, whereby data points at similar locations are grouped and the detection of outliers or inliers is handled at the group level. Specifically, a new algorithm NETS is proposed to achieve a remarkable performance improvement by realizing set-based early identification of outliers or inliers and taking advantage of the net effect between expired and new data points. Additionally, NETS is capable of achieving the same efficiency even for a high-dimensional data stream through two-level dimensional filtering. Comprehensive experiments using six real-world data streams show 5 to 25 times faster processing time than state-of-the-art algorithms with comparable memory consumption. We assert that NETS opens a new possibility to real-time data stream outlier detection
Topological Structure of Dense Hadronic Matter
We present a summary of work done on dense hadronic matter, based on the
Skyrme model, which provides a unified approach to high density, valid in the
large limit. In our picture, dense hadronic matter is described by the
{\em classical} soliton configuration with minimum energy for the given baryon
number density. By incorporating the meson fluctuations on such ground state we
obtain an effective Lagrangian for meson dynamics in a dense medium. Our
starting point has been the Skyrme model defined in terms of pions, thereafter
we have extended and improved the model by incorporating other degrees of
freedom such as dilaton, kaons and vector mesons.Comment: 13 pages, 8 figures, Talk given at the KIAS-APCTP Symposium in
Astro-Hadron Physics "Compact Stars: Quest for New States of Dense Matter",
November 10-14, 2003, Seoul, Korea, published by World Scientific. Based on
talk by B.-Y. Par
Half-Skyrmions, Tensor Forces and Symmetry Energy in Cold Dense Matter
In a previous article, the 4D half-skyrmion (or 5D dyonic salt) structure of
dense baryonic matter described in crystalline configuration in the large
limit was shown to impact nontrivially on how anti-kaons behave in compressed
nuclear matter with a possible implication on an "ice-9" phenomenon of deeply
bound kaonic matter and condensed kaons in compact stars. We extend the
analysis to make a further prediction on the scaling properties of hadrons that
have a surprising effect on the nuclear tensor forces, the symmetry energy and
hence on the phase structure at high density. We treat this problem relying on
certain topological structure of chiral solitons. Combined with what can be
deduced from hidden local symmetry for hadrons in dense medium and the "soft"
dilatonic degree of freedom associated with the trace anomaly of QCD, we
uncover a novel structure of chiral symmetry in the "supersoft" symmetry energy
that can influence the structure of neutron stars.Comment: 8 pages, 4 figures; contents unchanged but expanded for a journa
Skyrmions at finite density and temperature: The Chiral phase transition
The Skyrme model, an effective low energy theory rooted in large Nc QCD, has been applied to the study of dense matter. Matter is described by various crystal structures of skyrmions. When this system is heated, the dominating thermal degrees of freedom are the fluctuating pions. Taking these mechanisms jointly produces a description of the chiral phase transition leading to the conventional phase diagram with critical temperatures and densities in agreement with expected values
Baryonic Matter in the Hidden Local Symmetry Induced from Holographic QCD Models
Baryonic matter is studied in the Skyrme model by taking into account the
roles of , and mesons through the hidden local symmetry
up to terms including the homogeneous Wess-Zumino (hWZ)
terms. Using the master formulas for the low energy constants derived from
holographic QCD models the skyrmion matter properties can be quantitatively
calculated with the input values of the pion decay constant and the
vector meson mass . We find that the hWZ terms are responsible for
the repulsive interactions of the meson. In addition, the
self-consistently included terms with the hWZ terms is found
to increase the half skyrmion phase transition point above the normal nucleon
density.Comment: Contribution to SCGT12 "KMI-GCOE Workshop on Strong Coupling Gauge
Theories in the LHC Perspective", 4-7 Dec. 2012, Nagoya Universit
The pion velocity in dense skyrmion matter
We have developed a field theory formalism to calculate in-medium properties of hadrons within a unified approach that exploits a single Lagrangian to describe simultaneously both matter background and meson fluctuations. In this paper we discuss the consequences on physical observables of a possible phase transition of hadronic matter taking place in the chiral limit. We pay special attention to the pion velocity vπ, which controls, through a dispersion relation, the pion propagation in the hadronic medium. The vπ is defined in terms of parameters related to the matrix element in matter of the axial-vector current, namely, the in-medium pion decay constants, ft and fs. Both of the pion decay constants change dramatically with density and even vanish in the chiral limit when chiral symmetry is restored, but the pion velocity does not go to zero, decreasing at most 10% over the whole density range studied. A possible pseudogap structure is indicated
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