8,354 research outputs found
Decays of and into vector and pseudoscalar meson and the pseudoscalar glueball- mixing
We introduce a parametrization scheme for where
the effects of SU(3) flavor symmetry breaking and doubly OZI-rule violation
(DOZI) can be parametrized by certain parameters with explicit physical
interpretations. This scheme can be used to clarify the glueball-
mixing within the pseudoscalar mesons. We also include the contributions from
the electromagnetic (EM) decays of and via
. Via study of the isospin violated
channels, such as , ,
and , reasonable constraints on the EM decay
contributions are obtained. With the up-to-date experimental data for
, and , etc, we arrive at a consistent description of the mentioned
processes with a minimal set of parameters. As a consequence, we find that
there exists an overall suppression of the form factors,
which sheds some light on the long-standing " puzzle". By determining
the glueball components inside the pseudoscalar and in
three different glueball- mixing schemes, we deduce that the lowest
pseudoscalar glueball, if exists, has rather small component, and it
makes the a preferable candidate for glueball.Comment: Revised version to appear on J. Phys. G; An error in the code was
corrected. There's slight change to the numerical results, while the
conclusion is intac
Creation and control of a two-dimensional electron liquid at the bare SrTiO3 surface
Many-body interactions in transition-metal oxides give rise to a wide range
of functional properties, such as high-temperature superconductivity, colossal
magnetoresistance, or multiferroicity. The seminal recent discovery of a
two-dimensional electron gas (2DEG) at the interface of the insulating oxides
LaAlO3 and SrTiO3 represents an important milestone towards exploiting such
properties in all-oxide devices. This conducting interface shows a number of
appealing properties, including a high electron mobility, superconductivity,
and large magnetoresistance and can be patterned on the few-nanometer length
scale. However, the microscopic origin of the interface 2DEG is poorly
understood. Here, we show that a similar 2DEG, with an electron density as
large as 8x10^13 cm^-2, can be formed at the bare SrTiO3 surface. Furthermore,
we find that the 2DEG density can be controlled through exposure of the surface
to intense ultraviolet (UV) light. Subsequent angle-resolved photoemission
spectroscopy (ARPES) measurements reveal an unusual coexistence of a light
quasiparticle mass and signatures of strong many-body interactions.Comment: 14 pages, 4 figures, supplementary information (see other files
Hidden one-dimensional electronic structure and non-Fermi liquid angle resolved photoemission line shapes of -MoO
We report angle resolved photoemission (ARPES) spectra of
-MoO, a layered metal that undergoes two charge density wave
(CDW) transitions at 109 K and 30 K. We have directly observed the ``hidden
one-dimensional (hidden-1d)'' Fermi surface and an anisotropic gap opening
associated with the 109 K transition, in agreement with the band theoretical
description of the CDW transition. In addition, as in other hidden-1d materials
such as NaMoO, the ARPES line shapes show certain anomalies, which
we discuss in terms of non-Fermi liquid physics and possible roles of disorder.Comment: 3 figures; Erratum added to include missed reference
Crossover from Percolation to Self-Organized Criticality
We include immunity against fire as a new parameter into the self-organized
critical forest-fire model. When the immunity assumes a critical value,
clusters of burnt trees are identical to percolation clusters of random bond
percolation. As long as the immunity is below its critical value, the
asymptotic critical exponents are those of the original self-organized critical
model, i.e. the system performs a crossover from percolation to self-organized
criticality. We present a scaling theory and computer simulation results.Comment: 4 pages Revtex, two figures included, to be published in PR
Extracting the spectral function of the cuprates by a full two-dimensional analysis: Angle-resolved photoemission spectra of Bi2Sr2CuO6
Recently, angle-resolved photoemission spectroscopy (ARPES) has revealed a
dispersion anomaly at high binding energy near 0.3-0.5eV in various families of
the high-temperature superconductors. For further studies of this anomaly we
present a new two-dimensional fitting-scheme and apply it to high-statistics
ARPES data of the strongly-overdoped Bi2Sr2CuO6 cuprate superconductor. The
procedure allows us to extract theself-energy in an extended energy and
momentum range. It is found that the spectral function of Bi2Sr2CuO6 can be
parameterized using a small set of tight-binding parameters and a
weakly-momentum-dependent self-energy up to 0.7 eV in binding energy and over
the entire first Brillouin zone. Moreover the analysis gives an estimate of the
momentum dependence of the matrix element, a quantity, which is often neglected
in ARPES analyses.Comment: 8 pages, 5 figure
Doping dependence of the shadow band in La-based cuprates studied by angle-resolved photoemission spectroscopy
The shadow band (SB) in La-based cuprate family (La214) was
studied by angle-resolved photoemission spectroscopy (ARPES) over a wide doping
range from to . Unlike the well-studied case of the Bi-based
cuprate family, an overall strong, monotonic doping dependence of the SB
intensity at the Fermi level () was observed. In contrast to a previous
report for the presence of the SB only close to , we found it exists in
a wide doping range, associated with a doping-independent wave
vector but strongly doping-dependent intensity: It is the strongest at and systematically diminishes as the doping increases until it becomes
negligible in the overdoped regime. This SB with the observed doping dependence
of intensity can in principle be caused by the antiferromagnetic fluctuations
or a particular form of low-temperature orthorhombic lattice distortion known
to persist up to in the system, with both being weakened with
increasing doping. However, a detailed binding energy dependent analysis of the
SB at does not appear to support the former interpretation, leaving
the latter as a more plausible candidate, despite a challenge in quantitatively
linking the doping dependences of the SB intensity and the magnitude of the
lattice distortion. Our finding highlights the necessity of a careful and
global consideration of the inherent structural complications for correctly
understanding the cuprate Fermiology and its microscopic implication.Comment: Note the revised conclusion and author list; To appear in New J. Phy
Hydrodynamic characteristics of wing-in-ground effect oscillating hydrofoilon power extraction performance
The energy contained in the tidal motion of the seas and oceans has the potential to be a significant source ofrenewable energy. The oscillating hydrofoil current-energy turbine has a good performance to extract energyfrom the coupling of its heaving and pitching motions. In the present study, the wing-in-ground (WIG) effect hasbeen considered to improve the power-extraction performance of the oscillating hydrofoils. The overset grid inthe commercial computational fluid dynamic (CFD) software STAR CCM+ is applied to study the flapping hydrofoilwith dynamic WIG effect between two hydrofoils. The simulation results show that the WIG effect cangreatly improve the power extraction performance of the flapping hydrofoil. The WIG effect is asymmetric overthe course of the foil moving toward or leaving from the symmetry plane. The distance of the gap has a majorinfluence on the hydrodynamic performances of the flapping hydrofoil. For a moderate gap, the positive pressureon the lower surface enhances as the hydrofoil departs from the symmetry plane and causes an improvement oflift and moment coefficients. As the gap decreases further, the increasing negative pressure between the leadingedge and the symmetry plane plays an essential role improving the power extraction as the hydrofoil approachesthe symmetry plane. Compared to the case without the WIG effect, the power-extraction efficiency has anincrement of 16.34% in the present study
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Pointhuman: Reconstructing Clothed Human From Point Cloud Of Parametric Model
It is very difficult to accomplish the 3D reconstruction of the clothed human body from a single RGB image, because the 2D image lacks the representation information of the 3D human body, especially for the clothed human body. In order to solve this problem, we introduced a priority scheme of different body parts spatial information and proposed PointHuman network. PointHuman combines the spatial feature of the parametric model of the human body with the implicit functions without expressive restrictions. In PointHuman reconstruction framework, we use Point Transformer to extract the semantic spatial feature of the parametric model of the human body to regularize the implicit function of the neural network, which extends the generalization ability of the neural network to complex human poses and various styles of clothing. Moreover, considering the ambiguity of depth information, we estimate the depth of the parameterized model after point cloudization, and obtain an offset depth value. The offset depth value improves the consistency between the parameterized model and the neural implicit function, and accuracy of human reconstruction models. Finally, we optimize the restoration of the parametric model from a single image, and propose a depth perception method. This method further improves the estimation accuracy of the parametric model and finally improves the effectiveness of human reconstruction. Our method achieves competitive performance on the THuman dataset.Shenzhen Science and Technology Projects under Grant JCYJ20200109143035495 and Natural Science Foundation of Fujian Province (2022J011275)
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