Spectroscopic properties in Er3＋/yb3＋ Co-doped fluorophosphate glass

Using the technique of high-temperature melting, a new Er3＋/Yb3＋ co-doped fluorophosphate glass was prepared. The absorption and fluorescence spectra were investigated in depth. The effect of Er3＋ and Yb3＋ concentration on the spectroscopic properties of the glass sample was also discussed. According to the Judd Ofelt theory, the oscillator strength was computed. The lifetime of 4113/2 level （t-m） of Er3＋ ions was 8.23 ms, and the full width at half maximum of the dominating emission peak was 68 nm at 1.53 μm. The large stimulated emission cross section of the Er3＋ was calculated by the McCumher theory. The spectroscopic properties of Er3＋ ion were compared with those in different glasses. The full width at half maximum and σe are larger than those of other glass hosts, indicating this studied glass may be a potentially useful candidate for high-gain erbium-doped fiber amplifier.     

A Note on q-Deformed Two-Dimensional Yang-Mills and Open Topological Strings

In this note we make a test of the open topological string version of the OSV conjecture in the toric Calabi-Yau manifold X = O（-3） → P^2 with background D4-branes wrapped on Lagrangian submanifolds. The Dbrahe partition function reduces to an expectation value of some inserted operators of a q-deformed Yang Mills theory living on a chain of P^1 ＇s in the base p2 of X. At large N this partition function can be written as a sum over squares of chiral blocks, which are related to the open topological string amplitudes in the local p2 geometry with branes at both the outer and inner edges of the toric diagram. This is in agreement with the conjecture.     

Comment on ＇The scale-transformation of electromagnetic theory and its applications＇, ＇Distribution characteristic of scattering field for an ellipsoidal target irradiated by an electromagnetic wave from an arbitrary direction＇ and ＇Electric fields inside and outside an anisotropic dielectric sphere＇

It is shown that the ＇scale-transformation＇ method proposed by Li Ying-Le et al. is not applicable to the Maxwell theory.     

Parseval Theory of Complex Wavelet Transform for Wavelet Family Including Rotational Parameters

A rotational parameter Rθ has been introduced to complex wavelet transform （CWT）. The rotational CWT （RCWT） corresponds to a matrix element 〈φ｜U2（θ;μ;κ）[F〉 in the context of quantum mechanics, where U2（θ;μ;κ） is a two-mode rotational displacing-squeezing operator in the 〈η｜ representation. Based on this, the Parseval theorem and the inversion formula of RCWT have been proved. The concise proof not only manifestly shows the merit of Dirac＇s representation theory but also leads to a new orthogonal property of complex mother wavelets in parameter space.     

Dynamical Symmetry Breaking of Maximally Generalized Yang-Mills Model and Its Restoration at Finite Temperatures

In terms of the Nambu-Jona-Lasinio mechanism, dynamical breaking of gauge symmetry for the maximally generalized Vang-Mills model is investigated. The gauge symmetry behavior at finite temperature is also investigated and it is shown that the gauge symmetry broken dynamically at zero temperature can be restored at finite temperatures.     

Gasser-Leutwyler Coefficients of Chiral Lagrangian for Pseudoscalar Goldstone Bosons in Dyson-Schwinger Equations

Based on the Dyson-Schwinger equations of quark propagator in rainbow truncation with an effective gluon propagator, the ten unknown Gasser-Leutwyler coefficients of the chiral Lagrangian for pseudoscalar Goldstone bosons are predicted. The predicted values of Li with i= 1, 2,..., 10 are in a reasonable agreement with empirical values used widely in literature, and the values predicted by many other theoretical models with QCD characteristics.     

Elastic and Thermodynamic Properties of CdSe from First-Principles Calculations

The lattice parameters, bulk modulus, phase transition pressure, and temperature dependencies of the elastic constants cij of CdSe are investigated by using the Cambridge Serial Total Energy Package （CASTEP） program in the frame of Density Functional Theory （DFT）. It is found that the phase transitions from the ZB structure to the RS structure and from WZ structure to RS structure are 2.2 GPa and 2.8 GPa, respectively. Our results agree well with the available experimental data and other theoretical results. The aggregate elastic modulus （B, G, E, A ）, the Poisson＇s ratio （v）, the Griuneisen parameter （γ）, the Debye temperature θD on pressure and temperature are also successfully obtained.     

Shear Viscosity of Hot QED at Finite Chemical Potential from Kubo Formula

Within the framework of finite temperature field theory this paper discusses the shear viscosity of hot QED plasma through Kubo formula at one-loop skeleton diagram level with a finite chemical potential. The effective widths （damping rates） are introduced to regulate the pinch singularities and then gives a reliable estimation of the shear viscous coefficient. The finite chemical potential contributes positively compared to the pure temperature case. The result agrees with that from the kinetics theory qualitatively.     

Photodetachment of H- Near a Dielectric Surface

Using the closed orbit theory, the photodetachment cross section of H- near a dielectric surface has been derived and calculated. The results show that the dielectric surface has great influence on the photodetachment process of negative ion near the ionization threshold. Above the ionization threshold, the photodetachment cross section starts to oscillate. With the increase of the energy, the oscillating amplitude decreases and the oscillating frequency increases. The oscillation in the photodetachment cross section of H- in the presence of a dielectric surface is either larger or smaller than the photodetachment of H- without the surface. As the photon energy is larger than the critical value Epc, the oscillatory structure disappeared and the cross section approaches to the case of the photodetachment of H- without any external fields. For a given detached-electron energy, the photodetachment cross section becomes decreased with the increase of the ion-surface distance. Besides, the dielectric constant has great influence on the photodetachment of H-. With the increase of the dielectric constant, the oscillation in the cross section becomes increased. As the dielectric constant increases to infinity, the cross section is the same as the photodetachment of H- near a metal surface. This study provides a new understanding on the photodetachment process of H- in the presence of a dielectric surface.     

First-principles study of structural,electronic and optical properties of ZnF_2

The structural, electronic, and optical properties of rutile-, CaC12-, and PdF2-ZnF2 are calculated by the plane-wave pseudopotential method within the density functional theory. The calculated equilibrium lattice constants are in reasonable agreement with the available experimental and other calculated results. The band structures show that the rutile-, CaCl2-, and PdF2-ZnF2 are all direct band insulator. The band gaps are 3.63, 3.62, and 3.36 eV, respectively. The contribution of the different bands was analyzed by the density of states. The Mulliken population analysis is performed. A mixture of covalent and weak ionic chemical bonding exists in ZnF2. Furthermore, in order to understand the optical properties of ZnF2, the dielectric function, absorption coefficient, refractive index, electronic energy loss spectroscopy, and optical reflectivity are also performed in the energy range from 0 to 30 eV. It is found that the main absorption parts locate in the UV region for ZnF2. This is the first quantitative theoretical prediction of the electronic and optical properties of ZnF2 compound, and it still awaits experimental confirmation.     

Plasma neutrino energy loss due to the axial-vector current at the late stages of stellar evolution

Based on the Weinberg-Salam theory, the plasma neutrino energy loss rates of vector and axialvector contributions are studied. A ratable factor of the rates from the axial-vector current relative to those of the total neutrino energy loss rates is accurately calculated. The results show that the ratable factor will reach a maximum of 0.95 or even more at relatively higher temperature and lower density （such as p/μe 〈 10^7 g/cm^3）. Thus the rates of the axial-vector contribution cannot be neglected. On the other hand, the rates of the axialvector contribution are on the order of ~0.01% of the total vector contribution, which is in good agreement with Itoh＇s at relatively high density （such as p/μe 〉 10^7 g/cm^3） and a temperature of T ≤ 10^11 K.     

Centrality in High-Energy Nuclear Collisions and Random Matrix Theory.

I discuss the results from a study of the central ^12CC collisions at 4.2 A GeV/c. The data have been analyzed using a new method based on the Random Matrix Theory. The simulation data coming from the Ultra Relativistic Quantum Molecular Dynamics code were used in the analyses. I found that the behavior of the nearest neighbor spacing distribution for the protons, neutrons and neutral pions depends critically on the multiplicity of secondary particles for simulated data. I conclude that the obtained results offer the possibility of fixing the centrality using the critical values of the multiplicity.     

Excited nucleon electromagnetic form factors from broken spin-flavor symmetry

A group theoretical derivation of a relation between the N→△charge quadrupole transition and neutron charge form factors is presented.     

Energy levels of ls2n d （n ≤ 9） states for lithium-like ions

The full-core plus correlation method with multi-configuration interaction wave functions is extended to the calcu- lation of the non-relativistic energies of ls2nd （n ≤9） states for the lithium isoelectronic sequence from Z = 11 to 20. Relativistic and mass-polarization effects on the energy are calculated as the first-order perturbation correction. The quantum-electrodynamics correction is also included. The fine structure splittings are determined from the expectation values of spin-orbit and spin-other-orbit interaction operators in the Pauli-Breit approximation. Combining the term energies of lowly excited states obtained with the quantum defects calculated by the single channel quantum defect theory, each of which is a smooth function of energy and approximated by a weakly varying function of energy, the ion potentials of highly excited states （n ≥ 6） are obtained with the semi-empirical iteration method. The results are compared with experimental data in the literature and found to be closely consistent with the regularity.     

Effect of Varying Dzyaloshinskii-Moriya Interaction on the Bistable Nano-Scale Soliton Switching

The effect of Dzyaloshinskii-Moriya （D-M） interaction on the bistable nano-scale soliton switching offers the possiblity of developing a new innovative approach for data storage technology. The dynamics of Heisenberg ferromagnetic spin system is expressed in terms of generalized inhomogeneous higher order nonlinear Schr6dinger （NLS） equation. The bistable soliton switching in the ferromagnetic medium is established by solving the associated coupled evolution equations for amplitude and velocity of the soliton using the fourth order Runge-Kutta method numerically.     

Effective-Field Theory for Kinetic Ising Model on Honeycomb Lattice

As an analytical method, the effective-field theory （EFT） is used to study the dynamical response of the kinetic Ising model in the presence of a sinusoidal oscillating field. The effective-field equations of motion of the average magnetization are given for the honeycomb lattice （Z = 3）. The Liapunov exponent A is calculated for discussing the stability of the magnetization and it is used to determine the phase boundary. In the field amplitude ho / ZJ-temperature T/ZJ plane, the phase boundary separating the dynamic ordered and the disordered phase has been drawn. In contrast to previous analytical results that predicted a tricritical point separating a dynamic phase boundary line of continuous and discontinuous transitions, we find that the transition is always continuous. There is inconsistency between our results and previous analytical results, because they do not introduce sufficiently strong fluctuations.     

Properties and structure of N=Z nuclei within relativistic mean field theory

The axially deformed relativistic mean field theory with the force NLSH has been performed in the blocked BCS approximation to investigate the properties and structure of N=Z nuclei from Z=20 to Z=48. Some ground state quantities such as binding energies, quadrupole deformations, one/two-nucleon separation energies, root-mean-square （rms） radii of charge and neutron, and shell gaps have been calculated. The results suggest that large deformations can be found in medium-heavy nuclei with N=Z=38-42. The charge and neutron rms radii increase rapidly beyond the magic number N=Z=28 until Z=42 with increasing nucleon number, which is similar to isotope shift, yet beyond Z=42, they decrease dramatically as the structure changes greatly from Z=42 to Z=43. The evolution of shell gaps with proton number Z can be clearly observed. Besides the appearance of possible new shell closures, some conventional shell closures have been found to disappear in some region. In addition, we found that the Coulomb interaction is not strong enough to breakdown the shell structure of protons in the current region.     

Bose-Einstein Condensation in Linear Sigma Model at Hartree Approximation

The BEG of charged pions is investigated in the framework of O（4） linear sigma model. By using Cornwall- Jackiw-Tomboufis formalism, we have derived the gap equations for the effective masses of the mesons at finite temperature and finite isospin density. The critical temperature and phase diagram of BEG are discussed in the non-chiral limit at Hartree approximation.     

A Note on Black Hole Information Paradox in de Sitter Spacetimes

The possibility of stable or quasi-stable Planck mass black hole remnants as solution to the black hole information paradox is commonly believed phenomenologically unacceptable. Since we need a black hole remnant for every possible initial state, the number of remnants is expected to be infinite and that would lead to remnant pair production in any physical process with a total available energy roughly exceeding the Planck mass. In this note I point out that a positive cosmological constant of the Universe would naturally lead to an upper bound on the number of possible remnants.