1,734 research outputs found
Quantum Transport in Magnetic Topological Insulator Thin Films
The experimental observation of the long-sought quantum anomalous Hall effect
was recently reported in magnetically doped topological insulator thin films
[Chang et al., Science 340, 167 (2013)]. An intriguing observation is a rapid
decrease from the quantized plateau in the Hall conductance, accompanied by a
peak in the longitudinal conductance as a function of the gate voltage. Here,
we present a quantum transport theory with an effective model for magnetic
topological insulator thin films. The good agreement between theory and
experiment reveals that the measured transport originates from a topologically
nontrivial conduction band which, near its band edge, has concentrated Berry
curvature and a local maximum in group velocity. The indispensable roles of the
broken structure inversion and particle-hole symmetries are also revealed. The
results are instructive for future experiments and transport studies based on
first-principles calculations.Comment: 5 pages, 4 figure
The order analysis for the two loop corrections to lepton MDM
The experimental data of the magnetic dipole moment(MDM) of lepton(,
) is very exact. The deviation between the experimental data and the
standard model prediction maybe come from new physics contribution.
In the supersymmetric models, there are very many two loop diagrams
contributing to the lepton MDM. In supersymmetric models, we suppose two mass
scales and with for supersymmetric particles.
Squarks belong to and the other supersymmetric particles belong to
. We analyze the order of the contributions from the two loop diagrams. The
two loop triangle diagrams corresponding to the two loop self-energy diagram
satisfy Ward-identity, and their contributions possess particular factors. This
work can help to distinguish the important two loop diagrams giving corrections
to lepton MDM.Comment: 12 pages, 3 figure
Structural Stability of Lexical Semantic Spaces: Nouns in Chinese and French
Many studies in the neurosciences have dealt with the semantic processing of
words or categories, but few have looked into the semantic organization of the
lexicon thought as a system. The present study was designed to try to move
towards this goal, using both electrophysiological and corpus-based data, and
to compare two languages from different families: French and Mandarin Chinese.
We conducted an EEG-based semantic-decision experiment using 240 words from
eight categories (clothing, parts of a house, tools, vehicles,
fruits/vegetables, animals, body parts, and people) as the material. A
data-analysis method (correspondence analysis) commonly used in computational
linguistics was applied to the electrophysiological signals.
The present cross-language comparison indicated stability for the following
aspects of the languages' lexical semantic organizations: (1) the
living/nonliving distinction, which showed up as a main factor for both
languages; (2) greater dispersion of the living categories as compared to the
nonliving ones; (3) prototypicality of the \emph{animals} category within the
living categories, and with respect to the living/nonliving distinction; and
(4) the existence of a person-centered reference gradient. Our
electrophysiological analysis indicated stability of the networks at play in
each of these processes. Stability was also observed in the data taken from
word usage in the languages (synonyms and associated words obtained from
textual corpora).Comment: 17 pages, 4 figure
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