3,248 research outputs found
Spontaneous violation of chiral symmetry in QCD vacuum is the origin of baryon masses and determines baryon magnetic moments and their other static properties
A short review is presented of the spontaneous violation of chiral symmetry
in QCD vacuum. It is demonstrated, that this phenomenon is the origin of baryon
masses in QCD. The value of nucleon mass is calculated as well as the masses of
hyperons and some baryonic resonances and expressed mainly through the values
of quark condensates -- -- the vacuum
expectation values (v.e.v.) of quark field. The concept of vacuum expectation
values induced by external fields is introduced. It is demonstrated that such
v.e.v. induced by static electromagnetic field results in quark condensate
magnetic susceptibility, which plays the main role in determination of baryon
magnetic moments. The magnetic moments of proton, neutron and hyperons are
calculated. The results of calculation of baryon octet -decay constants
are also presented.Comment: 13 pades, 5 figures. Dedicated to 85-birthday of acad. S.T.Belyaev.
To be published in Phys.At.Nucl. Few references are correcte
Energy transport in strongly disordered superconductors and magnets
We develop an analytical theory for quantum phase transitions driven by
disorder in magnets and superconductors. We study these transitions with a
cavity approximation which becomes exact on a Bethe lattice with large
branching number. We find two different disordered phases, characterized by
very different relaxation rates, which both exhibit strong inhomogeneities
typical of glassy physics.Comment: 4 pages, 1 figur
Structure functions for light nuclei
We discuss the nuclear EMC effect with particular emphasis on recent data for
light nuclei including 2H, 3He, 4He, 9Be, 12C and 14N. In order to verify the
consistency of available data, we calculate the \chi^2 deviation between
different data sets. We find a good agreement between the results from the NMC,
SLAC E139, and HERMES experiments. However, our analysis indicates an overall
normalization offset of about 2% in the data from the recent JLab E03-103
experiment with respect to previous data for nuclei heavier than 3He. We also
discuss the extraction of the neutron/proton structure function ratio F2n/F2p
from the nuclear ratios 3He/2H and 2H/1H. Our analysis shows that the E03-103
data on 3He/2H require a renormalization of about 3% in order to be consistent
with the F2n/F2p ratio obtained from the NMC experiment. After such a
renormalization, the 3He data from the E03-103 data and HERMES experiments are
in a good agreement. Finally, we present a detailed comparison between data and
model calculations, which include a description of the nuclear binding, Fermi
motion and off-shell corrections to the structure functions of bound proton and
neutron, as well as the nuclear pion and shadowing corrections. Overall, a good
agreement with the available data for all nuclei is obtained.Comment: 18 pages, 7 figures, 5 tables, final version published in Phys. Rev.
Thermoelectric properties of Bi2Te3 atomic quintuple thin films
Motivated by recent experimental realizations of quintuple atomic layer films
of Bi2Te3,the thermoelectric figure of merit, ZT, of the quintuple layer is
calculated and found to increase by a factor of 10 (ZT = 7.2) compared to that
of the bulk at room temperature. The large enhancement in ZT results from the
change in the distribution of the valence band density of modes brought about
by the quantum confinement in the thin film. The theoretical model uses ab
initio electronic structure calculations (VASP) with full quantum-mechanical
structure relaxation combined with a Landauer formalism for the linear-response
transport coefficients.Comment: 4 figures, submitted to AP
Current algebra derivation of temperature dependence of hadron couplings with currents
The vector and the axial-vector meson couplings with the vector and the
axial-vector currents respectively at finite temperature have been obtained in
Ref. \cite{Mallik} by calculating all the relevant one-loop Feynman graphs with
vertices obtained from the effective chiral Lagrangian. On the other hand, the
same couplings were also derived in Ref.\cite{Ioffe1} by applying the method of
current algebra and the hypothesis of partial conservation of axial-vector
current (PCAC). The latter method appears to miss certain terms; in the case of
the vector meson coupling with the vector current, for example, a term
containing the coupling is missed. A similar situation would
also appear for the nucleon coupling with the nucleon current. In this note we
resolve these differences.Comment: 7 pages, 2 eps figure
Improving Small Object Proposals for Company Logo Detection
Many modern approaches for object detection are two-staged pipelines. The
first stage identifies regions of interest which are then classified in the
second stage. Faster R-CNN is such an approach for object detection which
combines both stages into a single pipeline. In this paper we apply Faster
R-CNN to the task of company logo detection. Motivated by its weak performance
on small object instances, we examine in detail both the proposal and the
classification stage with respect to a wide range of object sizes. We
investigate the influence of feature map resolution on the performance of those
stages.
Based on theoretical considerations, we introduce an improved scheme for
generating anchor proposals and propose a modification to Faster R-CNN which
leverages higher-resolution feature maps for small objects. We evaluate our
approach on the FlickrLogos dataset improving the RPN performance from 0.52 to
0.71 (MABO) and the detection performance from 0.52 to 0.67 (mAP).Comment: 8 Pages, ICMR 201
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