7,886 research outputs found
Phase equilibrium in two orbital model under magnetic field
The phase equilibrium in manganites under magnetic field is studied using a
two orbital model, based on the equivalent chemical potential principle for the
competitive phases. We focus on the magnetic field induced melting process of
CE phase in half-doped manganites. It is predicted that the homogenous CE phase
begins to decompose into coexisting ferromagnetic phase and CE phase once the
magnetic field exceeds the threshold field. In a more quantitative way, the
volume fractions of the two competitive phases in the phase separation regime
are evaluated.Comment: 4 pages, 4 figure
Resonant Bend Loss in Leakage Channel Fibers
Leakage channel fibers, designed to suppress higher-order modes, demonstrate
resonant power loss at certain critical radii of curvature. Outside the
resonance, the power recovers to the levels offset by the usual mechanism of
bend-induced loss. Using C-imaging, we experimentally characterize this
anomaly and identify the corresponding physical mechanism as the radiative
decay of the fundamental mode mediated by the resonant coupling to a cladding
mode.Comment: 3 pages, 4 figures, submitted to Optics Letter
NeuRec: On nonlinear transformation for personalized ranking
© 2018 International Joint Conferences on Artificial Intelligence. All right reserved. Modeling user-item interaction patterns is an important task for personalized recommendations. Many recommender systems are based on the assumption that there exists a linear relationship between users and items while neglecting the intricacy and non-linearity of real-life historical interactions. In this paper, we propose a neural network based recommendation model (NeuRec) that untangles the complexity of user-item interactions and establish an integrated network to combine non-linear transformation with latent factors. We further design two variants of NeuRec: userbased NeuRec and item-based NeuRec, by focusing on different aspects of the interaction matrix. Extensive experiments on four real-world datasets demonstrated their superior performances on personalized ranking task
Higgs phenomenology of supersymmetric economical 3-3-1 model
We explore the Higgs sector in the supersymmetric economical 3-3-1 model and
find new features in this sector. The charged Higgs sector is revised i.e., in
difference of the previous work, the exact eigenvalues and states are obtained
without any approximation. In this model, there are three Higgs bosons having
masses equal to that of the gauge bosons--the W and extra X and Y. There is one
scalar boson with mass of 91.4 GeV, which is closed to the boson mass and
in good agreement with present limit: 89.8 GeV at 95% CL. The condition of
eliminating for charged scalar tachyon leads to splitting of VEV at the first
symmetry breaking, namely, . The interactions among the
standard model gauge bosons and scalar fields in the framework of the
supersymmetric economical 3-3-1 model are presented. From these couplings, at
some limit, almost scalar Higgs fields can be recognized in accordance with the
standard model. The hadronic cross section for production of the bilepton
charged Higgs boson at the CERN LHC in the effective vector boson approximation
is calculated. Numerical evaluation shows that the cross section can exceed
35.8 fb.Comment: 33 pages, 1 figur
High-Performance Multi-Mode Ptychography Reconstruction on Distributed GPUs
Ptychography is an emerging imaging technique that is able to provide
wavelength-limited spatial resolution from specimen with extended lateral
dimensions. As a scanning microscopy method, a typical two-dimensional image
requires a number of data frames. As a diffraction-based imaging technique, the
real-space image has to be recovered through iterative reconstruction
algorithms. Due to these two inherent aspects, a ptychographic reconstruction
is generally a computation-intensive and time-consuming process, which limits
the throughput of this method. We report an accelerated version of the
multi-mode difference map algorithm for ptychography reconstruction using
multiple distributed GPUs. This approach leverages available scientific
computing packages in Python, including mpi4py and PyCUDA, with the core
computation functions implemented in CUDA C. We find that interestingly even
with MPI collective communications, the weak scaling in the number of GPU nodes
can still remain nearly constant. Most importantly, for realistic diffraction
measurements, we observe a speedup ranging from a factor of to
depending on the data size, which reduces the reconstruction time remarkably
from hours to typically about 1 minute and is thus critical for real-time data
processing and visualization.Comment: work presented in NYSDS 201
QCD Approach to B->D \pi Decays and CP Violation
The branching ratios and CP violations of the decays, including
both the color-allowed and the color-suppressed modes, are investigated in
detail within QCD framework by considering all diagrams which lead to three
effective currents of two quarks. An intrinsic mass scale as a dynamical gluon
mass is introduced to treat the infrared divergence caused by the soft
collinear approximation in the endpoint regions, and the Cutkosky rule is
adopted to deal with a physical-region singularity of the on mass-shell quark
propagators. When the dynamical gluon mass is regarded as a universal
scale, it is extracted to be around MeV from one of the
well-measured decay modes. The resulting predictions for all
branching ratios are in agreement with the current experimental measurements.
As these decays have no penguin contributions, there are no direct
asymmetries. Due to interference between the Cabibbo-suppressed and the
Cabibbo-favored amplitudes, mixing-induced CP violations are predicted in the
decays to be consistent with the experimental data at
1- level. More precise measurements will be helpful to extract weak
angle .Comment: 21pages,5 figures,3 tables, typos corrected and numerical result for
one of decay channels is improve
Edge states and topological orders in the spin liquid phases of star lattice
A group of novel materials can be mapped to the star lattice, which exhibits
some novel physical properties. We give the bulk-edge correspondence theory of
the star lattice and study the edge states and their topological orders in
different spin liquid phases. The bulk and edge-state energy structures and
Chern number depend on the spin liquid phases and hopping parameters because
the local spontaneous magnetic flux in the spin liquid phase breaks the time
reversal and space inversion symmetries. We give the characteristics of bulk
and edge energy structures and their corresponding Chern numbers in the
uniform, nematic and chiral spin liquids. In particular, we obtain analytically
the phase diagram of the topological orders for the chiral spin liquid states
SL[\phi,\phi,-2\phi], where \phi is the magnetic flux in two triangles and a
dodecagon in the unit cell. Moreover, we find the topological invariance for
the spin liquid phases, SL[\phi_{1},\phi_{2},-(\phi_{1}+\phi_{2})] and
SL[\phi_{2},\phi_{1},-(\phi_{1}+\phi_{2})]. The results reveal the relationship
between the energy-band and edge-state structures and their topological orders
of the star lattice.Comment: 7 pages, 8 figures, 1 tabl
Jahn-Teller distortion induced charge-ordering in CE phase of manganites
The charge order of CE phase in half-doped manganites is studied, based on an
argument that the charge-ordering is caused by the Jahn-Teller distortions of
MnO6 octahedra rather than Coulomb repulsion between electrons. The uantitative
calculation on the ferromagnetic zigzag chain as the basic structure unit of CE
phase within the framework of two-orbital double exchange model including
Jahn-Teller effect is performed, and it is shown that the
charge-disproportionation of Mn cations in the charge-ordered CE phase is less
than 13%. In addition, we predict the negative charge-disproportionation once
the Jahn-Teller effect is weak enough.Comment: 12 pages, 4 figures(contained in the pdf file). submitted to Physical
Review
Magnetic Excitations of Undoped Iron Oxypnictides
We study the magnetic excitations of undoped iron oxypnictides using a
three-dimensional Heisenberg model with single-ion anisotropy. Analytic forms
of the spin wave dispersion, velocities, and structure factor are given. Aside
from quantitative comparisons which can be made to inelastic neutron scattering
experiments, we also give qualitative criteria which can distinguish various
regimes of coupling strength. The magnetization reduction due to quantum zero
point fluctuations shows clear dependence on the c-axis coupling.Comment: 4 pages, 5 figures, to appear in Frontiers of Physics in China: a
special issue on Iron-based superconductor
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