Baryonium, tetraquark state and glueball in large-Nc QCD

From the large- QCD point of view, baryonia, tetraquark states, hybrids, and glueballs are studied. The existence of these states is argued for. They are constructed from baryons. In large- QCD, a baryonium is always identical to a glueball with valence gluons. The ground state glueball has a mass of about 2450 MeV. is identified as the lowest glueball. The lowest four-quark nonet should be , , and . Combining with the heavy quark effective theory, spectra of heavy baryonia and heavy tetraquark states are predicted. corrections are discussed. PACS 12.39.Mk; 14.20.-c; 12.38.Lg     

A study on the magnetic properties of two-phase particulate magnetic composites

The magnetic properties of two-phase particulate magnetic composites with a hard ferromagnetic component are studied theoretically and experimentally. The magnetic properties considered here are phase-distribution sensitive properties, including remanence, coercivity and the shape of hysteresis loop. These properties depend mainly on the properties of its constituents, volume fractions, phase distribution, packing fraction and orientation distribution for anisotropic particles. With fixed packing fraction and orientation distribution, the magnetic properties of the two phase mixture can be calculated in terms of its component properties, volume fractions and phase distribution. Here, the component properties include not only remanence B_r and coercivity H_c but also a variable m which is the rate of change of magnetic induction B with respect to field intensity H. For two-phase systems satisfying B - H relation of the type B = B_r + mH where m is a constant, the equations for calculating the magnetic properties B_r, H_c, etc., in terms of m are derived. The method for calculating m is also developed for the cases of parallel and series distributions. Bounds for m-values were also established. A modified Landauer's type equation is developed to calculate m-values in terms of the component properties of the mixture. Experiments were conducted to verify the theoretical calculations. Good agreements between the theoretical calculations and experimental results were obtained.     

Partially coherent anomalous hollow beam and its paraxial propagation

Anomalous hollow beam is extended to the partially coherent case. Analytical propagation formulae for a partially coherent anomalous hollow beam passing through a paraxial ABCD optical system are derived. The propagation properties of a partially coherent anomalous hollow beam in free space and the focusing properties of a partially coherent anomalous hollow beam are studied numerically. It is found that the propagation and focusing properties of the partially coherent anomalous hollow beam are closely related to its initial coherence.     

Structural,electric and pyroelectric properties of up and down graded PZT multilayers

Multi-layered structures, composed of thin films from materials with different compositions or physical properties, represents a way to obtain enhanced properties or even new functionalities. In this work, lead zirconate titanate PbZr_xTi_1-xO₃ (PZT; x = 0.20, 0.52, 0.80) multilayers were grown by pulsed laser deposition (PLD) on a single crystal strontium titanate (SrTiO₃, STO) substrate, using a strontium ruthenate (SrRuO₃, SRO) film as buffer layer for epitaxial growth, and also as back electrode.Up and down multi-layers were grown and their physical and structural properties were compared, up being the structure in which Zr concentration was varied from 20% near the STO substrate to 80% at the surface, while down is for the structure in which the Zr concentration starts with 80% near the substrate and ends with 20% at the surface. It was found that the electric and pyroelectric properties of the two graded structures are significantly different. The up structure presents electric properties that are comparable with those of single composition PZT films while the properties of the down structure are deteriorated, especially in terms of the leakage current magnitude. Pyroelectric signal could be measured only for the up structure. These differences were attributed to larger density of structural defects in the down structure compared to the up one. This is due to the different growth sequence: up structure starts with tetragonal PZT on cubic substrate (lower lattice mismatch, 1.1%) while down structure starts with rhombohedral PZT on cubic substrate (larger lattice mismatch, almost 5%).     

Scaling properties of randomly triangulated planar random surfaces: A numerical study

Results of Monte Carlo simulations of a model of random surfaces based on planar random triangulations with gaussian embedding in D-dimensional euclidean space are presented, for various positive and negative values of D and various forms for the action. Estimates are given for the fractal dimension (Hausdorff dimension of the embedding) and the spreading dimension (intrinsic Hausdorff dimension). The scaling properties appear to depend on the short-distance properties of the triangulations and seem to be nonuniversal, at least for positive D.     

Improved broad bandwidth intersections in photonic crystals

We theoretically investigate the transmission properties of a cascade of cavities coupled to waveguide by the time domain coupled-mode theory. Based on the theoretical analysis, broad bandwidth optical waveguide intersections in photonic crystals are modeled and optimized. The transmission properties are simulated by finite-difference time-domain method and transmission coefficients higher than 98% for a wide frequency range between 0.360 (2πc/a) and 0.364 (2πc/a) are obtained.     

Magnetic properties of NdSb,GdSb, TbSb,DySb, HbSb and ErSb under hydrostatic pressure

The hydrostatic pressure dependence of magnetic properties are reported for antiferromagnetic RSb where R = Nd, Gd, Tb, Dy, HoorEr. Measurements were made for pressures 0 ≤ p ≤ 10 kbar, magnetic fields 0 ≤ H₀ ≤ 60 kG, and temperatures 1.4 K ≤ T ≤ 35 K. dT_N/dP shows no systematic trend and ranges from -0.038 K/kbar for DySb to + 0.21 K/kbar for NdSb. The magnetic properties of DySb are strongly P-dependent, whereas those of HoSb are P-independent, but sample-dependent.     

Transport of waves in disordered waveguides: A potential model

We study the statistical properties of wave transport in a disordered waveguide. We first derive the properties of a “building block” (BB) of length δL starting from a potential model consisting of thin potential slices. We then find a diffusion equation—in the space of transfer matrices that describe our system—which governs the evolution with the length L of the disordered waveguide of the transport properties of interest. The latter depend only on the mean free paths and on no other property of the slice distribution. The universality that arises demonstrates the existence of a generalized central-limit theorem. We have developed a numerical simulation in which the universal statistical properties of the BB found analytically are first implemented numerically, and then the various BBs are combined to construct the full waveguide. The reported results thus obtained are in good agreement with microscopic calculations, for both bulk and surface disorder.     

On asymptotic properties of a quantum number ω in a system with SU(3) symmetry

The asymptotic properties of the basic vectors for the (λμ) irreducible representations of the SU(3)-group in the SU(3)?SO(3) reduction (Elliott's basis) are investigated for large values of λ or μ. The matrix of the Bargmann-Moshinsky operator Ω in Elliott's basis is analysed for the same limiting case. Approximate expressions for the eigenvalues and eigenvectors of the operator Ω are found. They demonstrate the asymptotic properties of the operator Ω to be very close to those of the rigid quantum top.     

Surface-induced optical anisotropy of inhomogeneous media

We demonstrate that the presence of interfaces induces anisotropy in the optical properties of thin inhomogeneous layers. Several mechanisms are discussed that can control the properties of this surface-induced anisotropy. We found that the effective refractive indices for s- and p-polarized fields are different and depend on the thickness of the layer, concentration and optical properties of inclusions in the layer, and the angle of incidence.     

SU(2) gluodynamics above the deconfinement temperature

A physical model for describing SU(2) gluodynamics above the deconfinement temperature is developed on the basis of the operator-product-expansion method. The properties of the nonperturbative vacuum are parametrized in terms of gauge-invariant gluomagnetic correlation functions. The free energy of the system is calculated for T>T _c. The results obtained within the proposed model for the thermal properties of gluons (energy density, nonideality) are shown to agree with data coming from lattice calculations.     

Structural physical regularities of the mechanism and kinetics of the formation of piezoelectric and ferroelectric crystals from a liquid phase

The specific features of the kinetics of formation of noncentrosymmetric crystals from electrolyte solutions are investigated for approximately 50 salts of M-N electrolytes. The “solubility product-limiting solution supercooling” set {SP-ΔT _m } for noncentrosymmetric crystals is separated into nine characteristic taxons in which the regularities of formation and growth of crystals are revealed and compared. It is demonstrated that the minimum supercoolings ΔT _m are observed for solutions of crystals with weak “acentric” properties. Higher supercoolings ΔT _m are observed for solutions of noncentrosymmetric crystals that belong to potential ferroelastics and exhibit pronounced acentric properties. The proposed taxonomy of electrolytes makes it possible to predict the conditions for the growth of perfect crystals for fundamental and applied physics.     

Correlation between structural and mechanical properties of PbTiO3 thin films grown by pulsed-laser deposition

Tetragonal lead titanate (PbTiO₃, PT) thin films are grown on (1 0 0) MgO substrate by pulsed-laser deposition (PLD) for expected applications in integrated optics. The realisation of outstanding and reliable devices into integrated circuits requires sufficient mechanical resistance despite that the obtained PT films display interesting waveguiding properties associated with low optical losses. Two mechanical properties characteristic of elasticity and hardness of PT films are studied. The elastic modulus (E or Young's modulus) and the hardness (H) are measured by the nanoindentation technique. These mechanical properties are correlated to the crystalline quality of PT/MgO thin films. The films show epitaxial relationship with the MgO substrate and the orientation of crystallites perpendicularly to the surface substrate may be the consequence of a growth process along c-axis, a-axis or both. Differences on curves plotting hardness and elastic modulus as a function of indentation depth are observed as the curves are less dispersed for the films mainly c-axis oriented.     

The Bethe-Goldstone equation with singular interactions: A fully off-shell solution for the boundary condition model

The mutual interaction of a pair of fermions imbedded in a many-body system of identical particles when they are excited out of the filled Fermi sea, is studied via the T-matrix or transition amplitude specified by the Bethe-Goldstone (BG) equation. The role of the bare two-body interaction is emphasised, and in particular the consequences are elucidated of whether the potential is “well-behaved” (nonsingular) or not. The properties of the BG T-matrix, including generalized orthonormality and completeness relations, are derived both for nonsingular potentials and for singular potentials containing an infinite hard core. General analytic properties are exploited to derive relations that express the fully off-shell BG T-matrix purely in terms of the half-shell amplitude (and the properties of any possible bound states in the medium). The general formalism is illustrated by deriving exact analytic expressions for the fully off-shell BG T-matrices for a pair of particles with equal and opposite momenta interacting via either of two singular model interactions; namely, the pure hard-core interaction and the boundary condition model. Results for both models are expressed in terms of the solution to a simple one-dimensional Fredholm integral equation. The analytic properties of the solutions are discussed and exploited to prove both their uniqueness and that they satisfy the various general relations derived. To our knowledge, these results represent the first exact nontrivial solution to the fully off-shell BG equation for any local potential, or singular limiting case thereof.     

Ferromagnetism in the high-pressure phases of (GaSb)1−x Mnx

The electrophysical and magnetic properties of recently discovered high-pressure phases in the GaSb-Mn system with simple cubic and tetragonal structures have been examined. It has been shown that samples with the primitive cubic structure for low temperatures are in the ferromagnetic state and the Curic temperature depends on the initial manganese content and reaches T _c = 280 K for x = 0.6. It has been shown that these samples for a manganese content x ≤ 0.5 are in the semiconducting state with large impurity conduction and pass to the metallic state as x increases. The GaSbMn phase with the tetragonal structure has ferromagnetic properties up to temperatures of T ～450 K (at which the phase begins to decay) and exhibits metallic properties. The magnetization at T = 77.3 K is equal to M = 0.58 μ_B and 0.28 μ_B per manganese ion for the simple cubic and tetragonal phases, respectively.     

Influence of doping of mercury atom(s) on optoelectronic properties of binary cadmium chalcogenides - A density functional theory based investigation with different exchange-correlation functionals and including spin-orbit coupling

Influence of doping of mercury atom(s) on optoelectronic properties of binary cadmium chalcogenides have been investigated theoretically by designing the mercury doped cadmium chalcogenide ternary alloys in B3 phase at some specific Hg-concentrations and studying their optoelectronic properties using DFT based FP-LAPW methodology. The structural properties are computed using WC-GGA, while spin-orbit coupling included electronic and optical properties are computed using TB-mBJ, EV-GGA, B3LYP and WC-GGA exchange-correlation functionals. In addition, electronic properties of mercury chalcogenides are calculated precisely using the GGA+U functionals. The concentration dependence of lattice parameter and bulk modulus of each of the Hg_xCd_1−xS, Hg_xCd_1−xSe, Hg_xCd_1−xTe alloy systems show almost linearity. For each of the alloy systems, band gap decreases almost linearly with increase in Hg-concentration in the unit cell and contribution from charge exchange to the band gap bowing is larger than that from for each of the volume deformation and structural relaxation. Also, covalent bonding exists between different constituent atoms in each compound. Optical properties of each specimen are computed from their spectra of dielectric function, refractive index, extinction coefficient, normal incidence reflectivity, optical conductivity, optical absorption coefficient and energy loss function. Several calculated results have been compared with available experimental and other theoretical data.     

A shell-model study onM1 andE2 properties of Zn,Ga, and Ge

Electromagnetic properties of Zn, Ga, and Ge are studied by using the nuclear shell model. Empirically determinedM1 operators are found to be very successful to explainM1 transitions, moments, and mixing ratios. ManyE2 properties are also understood by the present shell-model calculations with effective charges.     

Isovector Q balls

Finite-energy solutions rotating at a constant angular velocity in isovector space are considered within theories that possess global SO(3) symmetry (isovector theories). It is shown that, for a nonlinear O(3) model (n field), such solutions exist only in the one-dimensional case. For the isovector theory proposed by S. Weinberg in order to describe low-energy properties of the π mesons, such solutions exist at some values of parameters that appear in this theory. Some properties of these solutions are studied.     

Universal behavior in the scattering of heavy, weakly interacting dark matter on nuclear targets

Particles that are heavy compared to the electroweak scale (M?mW), and that are charged under electroweak SU(2) gauge interactions display universal properties such as a characteristic fine structure in the mass spectrum induced by electroweak symmetry breaking, and an approximately universal cross section for scattering on nuclear targets. The heavy particle effective theory framework is developed to compute these properties. As illustration, the spin independent cross section for low-velocity scattering on a nucleon is evaluated in the limit M?mW, including complete leading-order matching onto quark and gluon operators, renormalization analysis, and systematic treatment of perturbative and hadronic-input uncertainties.