2,571 research outputs found
violation in charmed hadron decays into neutral kaons
We find a new violating effect in charmed hadron decays into neutral
kaons, which is induced by the interference between the Cabibbo-favored and
doubly Cabibbo-suppressed amplitudes with the mixing.
It is estimated to be of order of , much larger than the
direct asymmetry, but missed in the literature. To reveal this new
violation effect, we propose a new observable, the difference of the
asymmetries in the and
modes. Once the new effect is determined by experiments, the direct
asymmetry then can be extracted and used to search for new physics.Comment: 6 pages, 3 figures. Contribution to the proceeding of The 15th
International Conference on Flavor Physics & CP Violation, 5-9 June 2017,
Prague, Czech Republi
Nonequilibrium Green's function approach to mesoscopic thermal transport
We present a formulation of a nonequilibrium Green's function method for
thermal current in nanojunction atomic systems with nonlinear interactions.
This first-principle approach is applied to the calculation of the thermal
conductance in carbon nanotube junctions. It is shown that nonlinearity already
becomes important at low temperatures. Nonlinear interactions greatly suppress
phonon transmission at room temperature. The peak of thermal conductance is
found to be around 400K, in good agreement with experiments. High-order phonon
scattering processes are important for diffusive heat transport.Comment: 4 pages, 4 figure
Origin of platelike granular structure for the ultrananocrystalline diamond films synthesized in H2-containing Ar/CH4 plasma
[[abstract]]The modification on microstructure of diamond films due to the incorporation of H2 species into the Ar/CH4 plasma was systematically investigated. While the hydrogen-free plasma produced the ultrananocrystalline diamond films with equiaxed grains (about 5 nm in size), the hydrogen-containing plasma resulted in platelike grains (about 100×300 nm2 in size). The size of the platelike grains increased with the H2 content in the plasma. Transmission electron microscopy and optical emission spectroscopy reveal that only 0.1%H2 incorporated in the Ar/CH4 plasma is sufficient for inducing the formation of platelike grains, suggesting that the platelike grains are formed via the competition between the attachment and the etching of hydrocarbons onto the existing diamond surfaces. In Ar plasma, the diamond grains were always passivated with hydrocarbons and the active carbon species in the plasma can only renucleate to form nanocrystalline diamond grains. Incorporation of H2 species in the plasma leads to partial etching of hydrocarbons adhered onto the diamond grains, such that active carbon species in the plasma can attach to diamond surface anisotropically, resulting in diamond flakes and dendrites geometry.[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子
Dry magnetic separation technology for the recovery of iron minerals in fine-grained steel slag
Using the MagNet software package, a permanent magnetic circuit was simulated and a sectorially-spliced magnetic system was designed. Consequently, a new roller permanent magnetic separator with different magnetic field intensities in each roller was developed. The modular structural design allows fine-grained minerals with different magnetic susceptibility to be separated in one pass, according to their different processing characteristic. Steel slag, selected from a factory, was crushed, ground and sieved into different particle size ranges for the single-factor magnetic separation experiments. It was determined that the optimum value ranges for the particle size, magnetic separation distance and rotating frequency were 0.15 mm-0.3 mm, 10 mm-12 mm, 40 Hz~60Hz, respectively; using the chosen parameter values of 0.2mm, 11mm, and 40Hz, the concentrate recovery and concentrate grade of the new separation technology reached up to 52.78% and 64.74%, in comparisson with the existing technology. Thus, it was demonstrated that the self-developed separation technology has the potential to improve the iron recovery of the fine-grained steel slag
Nature of in and decays
We investigate the decays of and
based on the picture where the resonance is strongly coupled to the
channel. In addition to the decay mechanism where the
resonance is formed from the pair hadronization with the
short-distance interaction, we have also considered the
rescattering diagrams in the long-distance scale, where and are
formed from and separately. Because of the difference of the mass
thresholds of charged and neutral channels, and the rather narrow
width of the resonance, at the mass, the loop functions of
and are much different. Taking this
difference into account, the ratio of can be naturally
obtained. Based on this result, we also evaluate the decay widths of . It is expected that future experimental measurements of
these decays can be used to elucidate the nature of the resonance.Comment: 7 pages, 5 figure
Solid State Implementation of Quantum Random Walks on General Graphs
Advances in recent years have made it possible to explore quantum dots as a
viable technology for scalable quantum information processing. Charge qubits
for example can be realized in the lowest bound states of coupled quantum dots
and the precision control of the confinement potential allows for the
realization of a full set of universal qubit gates, including arbitrary
single-qubit rotations and two-qubit C-NOT gates. In this work we describe a
novel scheme for implementing quantum random walks on arbitrarily complex
graphs by extending these elementary operations to the control of a
two-dimensional quantum dot grid. As single-qubit rotations constitute the
essential building blocks of our implementation scheme, we also present
numerical simulations of one such mechanism by directly solving the
corresponding time-dependent Schrodinger equation.Comment: 6 manuscript pages, 6 figures, to appear in the proceedings of the
2nd International Workshop on Solid-State Quantum Computing and the
Mini-School on Quantum Information Scienc
On the Generation of Medical Question-Answer Pairs
Question answering (QA) has achieved promising progress recently. However,
answering a question in real-world scenarios like the medical domain is still
challenging, due to the requirement of external knowledge and the insufficient
quantity of high-quality training data. In the light of these challenges, we
study the task of generating medical QA pairs in this paper. With the insight
that each medical question can be considered as a sample from the latent
distribution of questions given answers, we propose an automated medical QA
pair generation framework, consisting of an unsupervised key phrase detector
that explores unstructured material for validity, and a generator that involves
a multi-pass decoder to integrate structural knowledge for diversity. A series
of experiments have been conducted on a real-world dataset collected from the
National Medical Licensing Examination of China. Both automatic evaluation and
human annotation demonstrate the effectiveness of the proposed method. Further
investigation shows that, by incorporating the generated QA pairs for training,
significant improvement in terms of accuracy can be achieved for the
examination QA system.Comment: AAAI 202
- …