Testing Charmonium Production Mechanism via Polarized J/ψJ/\psi Pair Production at the LHC

At present the color-octet mechanism is still an important and debatable part in the non-relativistic QCD(NRQCD). We find in this work that the polarized double charmonium production at the LHC may pose a stringent test on the charmonium production mechanism. Result shows that the transverse momentum($p_T$) scaling behaviors of double $J/\psi$ differential cross sections in color-singlet and -octet production mechanisms deviate distinctively from each other while $p_T$ is larger than 7 GeV. In color-octet mechanism, the two $J/\psi$s in one pair are mostly transversely polarized when $p_T\gg 2 m_c$, as expected from the fragmentation limit point of view. In color-singlet mechanism, there is about one half of the charmonium pairs with at least one $J/\psi$ being longitudinally polarized at moderate transverse momentum. The energy dependence of the polarized $J/\psi$ pair production is found to be weak, and this process is found to be experimentally attainable in the early phase of the LHC operation.Comment: 16 pages, 5 figure

Indirect control of spin precession by electric field via spin-orbit coupling

The spin-orbit coupling (SOC) can mediate electric-dipole spin resonance (EDSR) in an a.c. electric field. In this letter, the EDSR is essentially understood as an spin precession under an effective a.c. magnetic field induced by the SOC in the reference frame, which is exactly following the classical trajectory of the electron and obtained by applying a quantum linear coordinate transformation. With this observation for one-dimensional (1D) case, we find a upper limit for the spin-flipping speed in the EDSR-based control of spin, which is given by the accessible data from the current experiment. For two-dimensional case, the azimuthal dependence of the effective magnetic field can be used to measure the ratio of the Rashba and Dresselhause SOC strengths.Comment: 11 pages, 6 figure

Quantum Routing of Single Photons with Cyclic Three-Level System

We propose an experimentally accessible single-photon routing scheme using a $\bigtriangleup$-type three-level atom embedded in quantum multi-channels composed of coupled-resonator waveguides. Via the on-demand classical field applied to the atom, the router can extract a single photon from the incident channel, and then redirect it into another. The efficient functions of perfect reflection of single photon signal in the incident channel is rooted in the coherent resonance and the existence of photonic bound states.Comment: 5 pages, 3 figure

Systematic study of α\alpha decay for isomer related nuclei within a two-potential approach

$\alpha$ decay occurs in both ground states and isomers of nuclei. In this work, we use the two-potential approach to systematically study whether isomeric states play a key role on $\alpha$ particle clustering or not. The results indicate the ratios of $\alpha$ decay preformation probabilities of isomers to ground states are found to be around 1

Systematic study of α\alpha decay half-lives for even-even nuclei within a two-potential approach

$\alpha$ decay is a common and important process for natural radioactivity of heavy and superheavy nuclei. The $\alpha$ decay half-lives for even-even nuclei from Z=62 to Z=118 are systematically researched based on the two-potential approach with a quasi-stationary state approximation. To describe the deviations between experimental half-lives and calculated results due to the nuclear shell structure, a hindrance factor related with $\alpha$ particle preformation probability is introduced. Our results can well reproduce the experimental data equally to the density-dependent cluster model and the generalized liquid drop model. We also study the isospin effect of nuclear potential in this work. Considering the isospin effect the calculated results improved about 7.3$\%$

Threshold for Non-Thermal Stabilization of Open Quantum Systems

We generally study whether or not the information of an open quantum system could be totally erased by its surrounding environment in the long time. For a harmonic oscillator coupled to a bath of a spectral density with zero-value regions, we quantitatively present a threshold of system-bath coupling \eta_{c}, above which the initial information of the system can remains partially as its long time stablization deviates from the usual thermalization. This non-thermal stabilization happens as a non-Markovian effect.Comment: 3 pages, 3 figure

Induction Networks for Few-Shot Text Classification

Text classification tends to struggle when data is deficient or when it needs to adapt to unseen classes. In such challenging scenarios, recent studies have used meta-learning to simulate the few-shot task, in which new queries are compared to a small support set at the sample-wise level. However, this sample-wise comparison may be severely disturbed by the various expressions in the same class. Therefore, we should be able to learn a general representation of each class in the support set and then compare it to new queries. In this paper, we propose a novel Induction Network to learn such a generalized class-wise representation, by innovatively leveraging the dynamic routing algorithm in meta-learning. In this way, we find the model is able to induce and generalize better. We evaluate the proposed model on a well-studied sentiment classification dataset (English) and a real-world dialogue intent classification dataset (Chinese). Experiment results show that on both datasets, the proposed model significantly outperforms the existing state-of-the-art approaches, proving the effectiveness of class-wise generalization in few-shot text classification.Comment: 7 pages, 3 figure

Logician: A Unified End-to-End Neural Approach for Open-Domain Information Extraction

In this paper, we consider the problem of open information extraction (OIE) for extracting entity and relation level intermediate structures from sentences in open-domain. We focus on four types of valuable intermediate structures (Relation, Attribute, Description, and Concept), and propose a unified knowledge expression form, SAOKE, to express them. We publicly release a data set which contains more than forty thousand sentences and the corresponding facts in the SAOKE format labeled by crowd-sourcing. To our knowledge, this is the largest publicly available human labeled data set for open information extraction tasks. Using this labeled SAOKE data set, we train an end-to-end neural model using the sequenceto-sequence paradigm, called Logician, to transform sentences into facts. For each sentence, different to existing algorithms which generally focus on extracting each single fact without concerning other possible facts, Logician performs a global optimization over all possible involved facts, in which facts not only compete with each other to attract the attention of words, but also cooperate to share words. An experimental study on various types of open domain relation extraction tasks reveals the consistent superiority of Logician to other states-of-the-art algorithms. The experiments verify the reasonableness of SAOKE format, the valuableness of SAOKE data set, the effectiveness of the proposed Logician model, and the feasibility of the methodology to apply end-to-end learning paradigm on supervised data sets for the challenging tasks of open information extraction

Atomic hydrogen adsorption and incipient hydrogenation of the Mg(0001) surface: A density-functional theory study

We investigate the atomic hydrogen adsorption on Mg(0001) by using density-functional theory within the generalized gradient approximation and a supercell approach. The coverage dependence of the adsorption structures and energetics is systematically studied for a wide range of coverage and adsorption sites. In the coverage range $0<\Theta<1.0, the most stable among all possible adsorption sites is the on-surface fcc site followed by the hcp site, and the binding energy increases with the coverage, thus indicating the higher stability of on-surface adsorption and a tendecy to the formation of H islands (clusters) when increasing the coverage within the region$0<\Theta<1.0. The on-surface diffusion path energetics of atomic hydrogen, as well as the activation barriers for hydrogen penetration from the on-surface to the subsurface sites, are also presented at low coverage. At high coverage of $1.00<\Theta<2.0, it is found that the coadsorption configuration with 1.0 monolayer of H's residing on the surface fcc sites and the remaining monolayer of H's occupying the subsurface tetra-I sites is most energetically favourable. The resultant H-Mg-H sandwich structure for this most stable coadsorption configuration displays similar spectral features to the bulk hydride MgH$_{2}$ in the density of states. The other properties of the H/Mg(0001) system, including the charge distribution, the lattice relaxation, the work function, and the electronic density of states, are also studied and discussed in detail. It is pointed out that the H-Mg chemical bonding during surface hydrogenation displays a mixed ionic/covalent character.Comment: 21 pages, 10 figure

Insight into the Microscopic Structure of an AdS Black Hole from the Quantization

We explore the possible microscopic structure of a charged AdS black hole from the quantized viewpoint. A further study shows that somehow some black holes may not be "black" from the view of quantization. By the quantization of the black hole horizon area, we show the relation between the number of quanta of area and the microscopic degrees of freedom of the black hole. We also interpret a latent heat of thermodynamical phase transition as a transition between the number of quanta of area of large black hole(LBH) and the number of quanta of area of small black hole(SBH) in the charged AdS black hole. Furthermore, the Ruppeiner scalar curvature connecting with the number of quanta of area is also shown.Comment: 15 page, 3 figure