29,799 research outputs found
Photon-meson transition form factors of light pseudoscalar mesons
The photon-meson transition form factors of light pseudoscalar mesons , , and are systematically calculated in a
light-cone framework, which is applicable as a light-cone quark model at low
and is also physically in accordance with the light-cone pQCD approach
at large . The calculated results agree with the available experimental
data at high energy scale. We also predict the low behaviors of the
photon-meson transition form factors of , and , which are measurable in process via Primakoff
effect at JLab and DESY.Comment: 22 Latex pages, 7 figures, Version to appear in PR
Crystal growth and magnetic structure of MnBi2Te4
Millimeter-sized MnBiTe single crystals are grown out of Bi-Te flux
and characterized by measuring magnetic and transport properties, scanning
tunneling microscope (STM) and spectroscopy (STS). The magnetic structure of
MnBiTe below T is determined by powder and single crystal neutron
diffraction measurements. Below T=24\,K, Mn moments order
ferromagnetically in the \textit{ab} plane but antiferromagnetically along the
crystallographic \textit{c} axis. The ordered moment is 4.04(13) /Mn
at 10\,K and aligned along the crystallographic \textit{c}-axis. The electrical
resistivity drops upon cooling across T or when going across the
metamagnetic transition in increasing fields below T. A critical scattering
effect was observed in the vicinity of T in the temperature dependence of
thermal conductivity. However, A linear temperature dependence was observed for
thermopower in the temperature range 2K-300K without any anomaly around T.
These indicate that the magnetic order in Mn-Te layer has negligible effect on
the electronic band structure, which makes possible the realization of proposed
topological properties in MnBiTe after fine tuning of the electronic
band structure
Parsec-scale jet properties of the gamma-ray quasar 3C 286
The quasar 3C~286 is one of two compact steep spectrum sources detected by
the {\it Fermi}/LAT. Here, we investigate the radio properties of the
parsec(pc)-scale jet and its (possible) association with the -ray
emission in 3C~286. The Very Long Baseline Interferometry (VLBI) images at
various frequencies reveal a one-sided core--jet structure extending to the
southwest at a projected distance of 1 kpc. The component at the jet base
showing an inverted spectrum is identified as the core, with a mean brightness
temperature of ~K. The jet bends at about 600 pc (in
projection) away from the core, from a position angle of to
. Based on the available VLBI data, we inferred the proper motion
speed of the inner jet as mas yr (), corresponding to a jet speed of about at an inclination
angle of between the jet and the line of sight of the observer. The
brightness temperature, jet speed and Lorentz factor are much lower than those
of -ray-emitting blazars, implying that the pc-scale jet in 3C~286 is
mildly relativistic. Unlike blazars in which -ray emission is in
general thought to originate from the beamed innermost jet, the location and
mechanism of -ray emission in 3C~286 may be different as indicated by
the current radio data. Multi-band spectrum fitting may offer a complementary
diagnostic clue of the -ray production mechanism in this source.Comment: 9 pages, 4 figures, accept for publication in MNRA
Anatomical features of the radial artery in the Xinjiang population in China and its impact on the transradial coronary intervention procedure
Background: The anatomical features of the radial artery (RA) influence the transradial coronary intervention. The aim of this study is to discuss the anatomical features of the RA in the Xinjiang population and to guide interventionists in decreasing complications and improving success rates.
Materials and methods: We enrolled 1731 patients in this study. All relevant basic information was recorded in detail, and the RA diameter was examined. Patients were divided into a RA variation group and a RA non-variation group; univariate and multivariate factor analyses were performed to evaluate the relevant factors for RA diameter and the predictive value of the variable factors in RA variations.
Results: The mean RA diameter for all patients was 3.01 ± 0.14 mm. The multi-factorial analysis showed that height, gender, and occupation are significantly associated with RA diameter (p < 0.05). The incidence of RA variation was 4.97% (86/1731). Multi-factorial analysis showed that: gender (OR 2.72, 95% CI 1.469–5.037, p < 0.01), occupation (OR 2.228, 95% CI 1.0.000–0.012, p < 0.001) and RA inner diameter (OR 0.002, 95% CI 0.000–0.012, p < 0.001) are significantly associated with the incidence of RA variation.
Conclusions: The mean RA diameter in the Xinjiang population was 3.01 ± 0.14 mm, height, gender, occupation are associated with RA diameter, gender, farmer, RA diameter are associated with RA variation. These factors can guide the interventionists to choose the appropriate equipment before the operation then can increase the efficiency of operation and prevent from the complications
A study of manufacturing tubes with nano/ultrafine grain structure by stagger spinning
A new method of manufacturing tubes with nano/ultrafine grain structure by stagger spinning and recrystallization annealing is proposed in this study. Two methods of the stagger spinning process are developed, the corresponding macroforming quality, microstructural evolution and mechanical properties of the spun tubes made of ASTM 1020 steel are analysed. The results reveal that a good surface smoothness and an improved spin-formability of spun parts can be obtained by the process combining of 3-pass spinning followed by a 580 °C × 0.5 h static recrystallization and 2-pass spinning with a 580 °C × 1 h static recrystallization annealing under the severe thinning ratio of wall thickness reduction. The ferritic grains with an average initial size of 50 μm are refined to 500 nm after stagger spinning under the 87% thinning ratio of wall thickness reduction. The equiaxial ferritic grains with an average size of 600 nm are generated through re-nucleation and grain growth by subsequent recrystallization annealing at 580 °C for 1 h heat preservation. The tensile strength of spun tubes has been founded to be proportional to the reciprocal of layer spacing of pearlite (LSP), and the elongation is inversely proportional to the reciprocal of LSP. This study shows that the developed method of stagger power spinning has the potential to be used to manufacture bulk metal components with nano/ultrafine grain structure
Some recent progress on quark pairings in dense quark and nuclear matter
We give a brief overview on some recent progress in quark pairings in dense
quark/nuclear matter mostly developed in the past five years. We focus on
following aspects in particular: the BCS-BEC crossover in the CSC phase, the
baryon formation and dissociation in dense quark/nuclear matter, the
Ginzburg-Landau theory for three-flavor dense matter with (1) anomaly,
and the collective and Nambu-Goldstone modes for the spin-one CSC.Comment: RevTex 4, 25 pages, 9 figures, presented for the KITPC (Kavli
Institute for Theoretical Physics China) program "AdS/CFT and Novel
Approaches to Hadron and Heavy Ion Physics' in Oct. 11- Dec. 3, 201
How to realize Lie algebras by vector fields
An algorithm for embedding finite dimensional Lie algebras into Lie algebras
of vector fields (and Lie superalgebras into Lie superalgebras of vector
fields) is offered in a way applicable over ground fields of any
characteristic. The algorithm is illustrated by reproducing Cartan's
interpretations of the Lie algebra of G(2) as the Lie algebra that preserves
certain non-integrable distributions. Similar algorithm and interpretation are
applicable to other exceptional simple Lie algebras, as well as to all
non-exceptional simple ones and many non-simple ones, and to many Lie
superalgebras.Comment: 17 pages, LaTe
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