Static properties of chiral soliton in a nonlinear σ-field with ρ-meson coupling

The soliton soluton for a lagrangian made of a nonlinear σ-field coupled to a ρ-meson field is studied. The static properties are calculated and compared with experimental values and the results of the Skyrme model.     

Stabilization of skyrmions via ϱ-mesons

It is shown that a skyrion can be stabilized by introducing ?-mesons into the chiral SU(2)_L × SU(2)_R lagrangian without higher-derivative terms like the Skyrme term. The ?-mesons are considered as dynamical gauge bosons associated with a hidden local symmetry of the non-linear sigma model. The lagrangian reduces to the Skyrme model in a limit of parameters. The Skyrmion mass M is found to be M = 1058 MeV when the parameters are fixed so as to satisfy the KSRF relation. It is also shown that a solition solution in a model with Ω-meson coupled with the baryonic current is a saddle-point solution.     

Evaluation of the Skyrme parameter from QCD sum rules

The dimensionless parameter of the Skyrme lagrangian is evaluated by two methods. In one a combination of sum rules for the nucleon and the pion is used, in the other only baryonic sum rules. e = 5−8 and e = 5−7 is found, respectively, in agreement with the phenomenological value e = 5.45. To leading order in the operator-product expansion the analytical expression of e does not depend on the chiral-symmetry-breaking parameters.     

The skyrmion-skyrmion interaction

Using the Skyrme effective lagrangian, baryons emerge as topological solitons. This effective lagrangian is used in adiabatic calculations aimed at providing an essentially parameter-free model of the interaction between such solitons. The resulting skyrmion-skyrmion interaction can be understood as terms simulating the exchange of π-, ρ-, and ω-mesons between the solitons. It is readily transformed (by essentially projective techniques) into a low-energy nucleon-nucleon potential. Comparisons of this potential with the best available semiphenomenological nucleon-nucleon interactions are found to be successful at the 30% level. Similarities between the Skyrme model and the quark chiral-bag model are discussed.     

Comparison between global phenomenological and microscopic optical potentials for proton as projectile below 100 MeV

For 112 target nuclei (52 elements) with proton as projectile, we calculate the reaction cross sections and elastic scattering angular distributions, as well as the X2 values for 16 kinds of proton optical model potentials: two sets of phenomenological global optical potentials and the microscopic optical potentials proposed by Shen et al for 14 sets of Skyrme force parameters: GSI-6, SBJS, SKM, SGI-Ⅱ, SKa-b, SG01-Ⅱ.We find that for obtaining the proton microscopic optical potential based on the nuclear matter approach with Skyrme force, SGI, SKa and SKb are the three sets of optimal Skyrme force parameters.     

The manifold of solutions of Roy's S- and P-wave equations for pion-pion scattering: The neighbourhood of the physical amplitudes

We study the solutions of the coupled S- and P-wave Roy equations for low-energy pion-pion scattering which are in the neighbourhood of a given solution. We give a general method for constructing these solutions for fixed inelasticities and driving terms and variable S-wave scattering lengths. In the case of the neighbourhood of the physical amplitudes, our procedure leads to a seven-dimensional manifold of solutions. If we omit variations affecting only the I = 0 S-wave around the $\text{K}\text{K}$ threshold, the number of dimensions is reduced to five, in accordance with the results of the phenomenological analysis of low-energy pion-pion scattering. Our solutions allow a study of the correlations between S- and P-waves implied by the Roy equations. This work completes a previous one dealing with the single-channel problem of the I = 1 P-wave.     

Zur Analytizität der Streuamplitude und Unitarität des Streuoperators bei der π-π-Wechselwirkung

The limitations which unitarity imposes on the magnitudes of the residues for the scattering amplitude in an effective range treatment of pion-pion scattering are investigated. The conditions (5) and (6) are derived.     

Coaxial Waveguide Slot Bridge Cell for Liquid Substances Study

The experimental method suggested suppose the studying of energy characteristics of slot bridge (SB) cells in the multi mode operating regime based on the preliminary numerical investigation of scattering resonant characteristics of SB (solution of boundary value problem and investigation of eigen frequencies and relevant field modes). The configuration of experimental model of SB cell is computed accordingly to required frequency band and preliminary information about dielectric parameters of materials chosen for tests. Ethanol scattering characteristics of SB cell are computed by software, developed on the base of rigorous solution of the boundary value problem, providing numerical data with any required accuracy.     

Isoscalar charge radius of the chiral bag

We calculate the contribution of the fermionic vacuum in the bag to the isoscalar charge radius (ICR) of the baryon. ICR can be evaluated as a function of the bag radiusR, the chiral angle θ at the surface of the bag and the parameters characterizing outer pion cloud, e.g.e andF _π in the Skyrme lagrangian.     

Pion-pion scattering lengths from Veneziano formula and η→3π,K→3π decays

Theη→ 3π decay amplitude is factorized into (a) the transition matrix element fromη toπ ⁰ and (b) Lovelace's expression of the Veneziano type for the pion-pion scattering amplitude. (a) is related with the electromagnetic mass splitting betweenK ⁺ andK ⁰. The absolute value of (b) is then obtained by fitting theη decay width. The pion-pion scattering lengths from (b) are reasonable. Since the analogous treatment ofK→ 3π decay together with a soft-pion determination of theK→π transition matrix element yield very small scattering lengths we suggest that theK→2π transition matrix element depends strongly on the pion masses.     

The boundary value problem in fermion systems

The half-space boundary value problem for fermions near zero temperature in plane geometry is solved for diffuse boundary scattering by numerically constructing the spatial propagator in terms of the eigenfunctions of a generalized eigenvalue problem for the linearized Uehling-Uhlenbeck collision integral. The slip length is calculated for several interparticle scattering laws and compared with a relaxation time ansatz result and the experimental values for normal fluid³He. It is shown that the nonsingular part of the collision operator is relatively compact to the singular part.     

Features of the π0π0 system produced in 5π final states by 3.5 GeV/cπ+

Angular correlations between two pions in the 5-pion final states are studied. A comparison between neutral, like-charged and unlike-charged pion-pion system is done. Evidence is shown for a strong π⁰π⁰ correlation in the asymmetry parameters as well as in the mass distribution. This effect is interpreted in terms of the scattering length approximation.     

Relativistic description of deformed rare earth nuclei

Ground state properties of heavy deformed nuclei in the rare earth region are described in the framework of the relativistic Hartree approximation. Both linear and non-linear parameter sets of the lagrangian are used. The non-linear sets reproduce the experimentally observed binding energies, the charge radii and the quadrupole moments, with the same quality as non-relativistic density dependent mean field calculations with Skyrme forces.     

Two-dimensional shear waves scattering by a large rigidity strip with interface crack

A two-dimensional problem of shear horizontal (SH) waves scattering by a finite width planar elastic (piezoelectric) inclusion partially debonded from its surrounding elastic matrix is investigated using the effective boundary conditions and singular integral equations technique. The case of large rigidity inclusions with blunted tips is considered, in which the upper face of the inclusion is perfectly bonded to the matrix. The debonding region is modeled as interface crack with non-contacting faces. Using the Green theorem the mixed boundary value problem is reduced to a system of the hypersingular integral equations. Numerical results of the scattering fields characteristics are presented. The effects of incidence direction, various material parameters of the strip on the scattering field are discussed and phenomenon of the non-specular reflection of SH waves is considered. The accuracy of the numerical results is confirmed by the use of analytical approximate problem solution of high-frequency SH waves scattering on a finite hard/soft inclusion.     

πN SCATTERING PHASE SHIFTS IN A MODIFIED SKYRME MODEL

The P-wave phase shift of πN scattering and the mass and width of the Roper resonance are computed in a modified Skyrme model.The results are better than those calculated from the original Skyrme model.     

Lattice QCD Calculation of ππ Scattering Length

We study s-wave pion-pion scattering length in lattice QCD for pion masses ranging from 330 MeV to 466 MeV.In the "Asqtad" improved staggered fermion formulation,we measure full ππ four-point correlators for isospin I = 0 and 2 channels,and use chiral perturbation theory at next-to-leading order to extrapolate our simulation results.Extrapolating to the physical pion mass yields scattering lengths as mπaI=2 0 = 0.041 6(2) and m π a I =0 0 = 0.186(2) for isospin I = 2 and 0 channels,respectively.Our lattice simulation for ππ scattering length in I = 0 channel is an exploratory study,where we include the disconnected contribution,and our preliminary result is near to its experimental value.These simulations are carried out with MILC 2 + 1 flavor gauge configurations at lattice spacing a ≈ 0.15 fm.     

Stability of a pretwisted tapered cantilever beam subjected to dissipative and follower forces

Stability of a pretwisted tapered cantilever beam of rectangular cross-section subjected to a follower force at its free end is investigated. The effects of internal and external damping are included in the study. The non-self-adjoint boundary value problem is formulated with the Euler-Bernoulli theory and an associated adjoint boundary value problem is introduced. Approximate values of the critical load are calculated on the basis of a suitable adjoint variational principle for several values of the geometric and material parameters of the beam. The results are shown in graphs.