Topological Excitation in Skyrme Theory

Based on the $\phi$-mapping topological current theory and the decomposition of gauge potential theory, we investigate knotted vortex lines and monopoles in Skyrme theory and simply discuss the branch processes (splitting, merging and intersection) during the evolution of the monopoles.Comment: 10 pages, 0 figure

Dilaton gravity approach to three dimensional Lifshitz black hole

The z=3 Lifshitz black hole is an exact black hole solution to the new massive gravity in three dimensions. In order to understand this black hole clearly, we perform a dimensional reduction to two dimensional dilaton gravity by utilizing the circular symmetry. Considering the linear dilaton, we find the same Lifshitz black hole in two dimensions. This implies that all thermodynamic quantities of the z=3 Lifshitz black hole could be obtained from its corresponding black hole in two dimensions. As a result, we derive the temperature, mass, heat capacity, Bekesnstein-Hawking entropy, and free energy.Comment: 13 pages, 1 figure, version to appear in EPJ

Gravitational Corrections to the Energy-Levels of a Hydrogen Atom

The first order perturbations of the energy levels of a hydrogen atom in central internal gravitational field are investigated. The internal gravitational field is produced by the mass of the atomic nucleus. The energy shifts are calculated for the relativistic 1S, 2S, 2P, 3S, 3P, 3D, 4S and 4P levels with Schwarzschild metric. The calculated results show that the gravitational corrections are sensitive to the total angular momentum quantum number.Comment: 7 page

Does the enhancement observed in γγ→DDˉ\gamma\gamma\to D\bar{D} contain two PP-wave higher charmonia?

Solved is a new puzzle raised by the observation of an enhancement structure Z(3930) in $\gamma\gamma\to D\bar{D}$. If categorizing Z(3930) as $\chi_{c2}(2P)$ suggested by Belle and BaBar, we must explain why $\chi_{c0}(2P)$ dominantly decaying into $D\bar{D}$ is missing in the $D\bar{D}$ invariant mass spectrum. In this work, we propose that the Z(3930) enhancement structure may contain two $P$-wave higher charmonia {$\chi_{c0}(2P)$} and $\chi_{c2}(2P)$. We show that this assumption is supported by our analysis of the $D\bar{D}$ invariant mass spectrum and $\cos\theta^\ast$ distribution of $\gamma\gamma\to D\bar{D}$. This observation would not only provide valuable information of two P-wave higher charmonia $\chi_{c0}(2P)$ and $\chi_{c2}(2P)$, but also serve as the crucial test of our novel proposal to the observed enhancement structure Z(3930), especially at the forthcoming BelleII and the approved SuperB.Comment: 5 pages, 2 tables, 3 figures. More contents and discussions adde

Short-segment posterior instrumentation combined with calcium sulfate cement vertebroplasty for thoracolumbar compression fractures: Radiographic outcomes including nonunion and other complications

AbstractObjectiveTo evaluate the radiographic outcomes of short-segment posterior instrumentation plus vertebroplasty using injectable calcium sulfate cement (CSC) for thoracolumbar compression fractures.Materials and methodsTwenty-eight patients with a single-level thoracolumbar compression fracture, who underwent short-segment pedicle screw fixation and CSC vertebroplasty, were included in the study. The anterior vertebral body height ratio, local kyphosis angle, and the height of the intervertebral disc adjacent to the fractured vertebra were used to evaluate the radiographic results. Complications including bone nonunion, instrument failure, cement leakage, and disc vacuum formation were also assessed.ResultsThe patients were followed up for an average of 24.20±5.40 months. The relative preoperative anterior body height was 55.71±15.29%, which improved to 94.93±5.39% immediately after surgery (P<0.001), and at final follow-up showed a 6.50±3.89% loss of height correction (P<0.001). The mean preoperative local kyphosis angle was 22.23±5.65°, which corrected to 2.67±4.43° immediately after surgery (P<0.001), but reverted to 6.71±4.95° at final follow-up, showing a 4.04±1.91° loss of correction (P<0.001). The mean height of the intervertebral disc proximal to the fractured vertebra was 9.87±0.91mm before surgery, 12.53±0.98mm after operation (P<0.001), and the loss of correction at final follow-up was 2.35±1.15mm with a significant difference compared to immediate postoperative values (P<0.001). Bone nonunion occurred in 7 patients, 2 patients had hardware failure, 9 patients had cement leakage, and 10 patients had disc vacuum phenomenon adjacent to the fractured vertebra.ConclusionsThe patients who underwent this procedure had a loss of correction of vertebral height and local kyphosis. Complications such as bone nonunion, instrument failure, cement leakage, and disc vacuum may occur. Rapid CSC resorption accounts for these radiographic outcomes and complications.Level of evidenceLevel IV, retrospective study

The Use of Dispersion Relations in the ππ\pi\pi and KKˉK\bar K Coupled-Channel System

Systematic and careful studies are made on the properties of the IJ=00 $\pi\pi$ and $K\bar K$ coupled-channel system, using newly derived dispersion relations between the phase shifts and poles and cuts. The effects of nearby branch point singularities to the determination of the $f_0(980)$ resonance are estimated and and discussed.Comment: 22 pages with 5 eps figures. A numerical bug in previous version is fixed, discussions slightly expanded. No major conclusion is change

Does entropic force always imply the Newtonian force law?

We study the entropic force by introducing a bound $S \le A^{3/4}$ between entropy and area which was derived by imposing the non-gravitational collapse condition. In this case, applying a modified entropic force to this system does not lead to the Newtonian force law.Comment: 11 pages, version to appear in EPJ

Multiple-path Quantum Interference Effects in a Double-Aharonov-Bohm Interferometer

We investigate quantum interference effects in a double-Aharonov-Bohm (AB) interferometer consisting of five quantum dots sandwiched between two metallic electrodes in the case of symmetric dot-electrode couplings by the use of the Green’s function equation of motion method. The analytical expression for the linear conductance at zero temperature is derived to interpret numerical results. A three-peak structure in the linear conductance spectrum may evolve into a double-peak structure, and two Fano dips (zero conductance points) may appear in the quantum system when the energy levels of quantum dots in arms are not aligned with one another. The AB oscillation for the magnetic flux threading the double-AB interferometer is also investigated in this paper. Our results show the period of AB oscillation can be converted from 2π to π by controlling the difference of the magnetic fluxes threading the two quantum rings

Long-distant contribution and χc1\chi_{c1} radiative decays to light vector meson

The discrepancy between the PQCD calculation and the CLEO data for $\chi_{c1}\to \gamma V$ ($V=\rho^0,\,\omega,\,\phi$) stimulates our interest in exploring extra mechanism of $\chi_{c1}$ decay. In this work, we apply an important non-perturbative QCD effect, i.e., hadronic loop mechanism, to study $\chi_{c1}\to \gamma V$ radiative decay. Our numerical result shows that the theoretical results including the hadronic loop contribution and the PQCD calculation of $\chi_{c1}\to \gamma V$ are consistent with the corresponding CLEO data of $\chi_{c1}\to \gamma V$. We expect further experimental measurement of $\chi_{c1}\to \gamma V$ at BES-III, which will be helpful to test the hadronic loop effect on $\chi_{c1}$ decay.Comment: 7 pages, 2 figures. Accepted for publication in Eur. Phys. J.