A mathematical model for wave propagation in elastic tubes with inhomogeneities: Application to blood waves propagation

We study the propagation of waves in an elastic tube filled with an inviscid fluid. We consider the case of inhomogeneity whose mechanical and geometrical properties vary in space. We deduce a system of equations of the Boussinesq type as describing the wave propagation in the tube. Numerical simulations of these equations show that inhomogeneities prevent separation of right-going from left-going waves. Then reflected and transmitted coefficients are obtained in the case of localized constriction and localized rigidity. Next we focus on wavetrains incident on various types of anomalous regions. We show that the existence of anomalous regions modifies the wavetrain patterns. (c) 2007 Elsevier B.V. All rights reserved.

Analysis of the Hb(b)over-bar coupling constant and CP-violation effects at the future e(+)e(-) collider

The e(+)e(-)-->b (B) over bar nu(ν) over bar process, where nu is an electron, muon, or tau-lepton neutrino, is analyzed in detail for the general form of the coupling constant of a Higgs boson with b quarks, with the (m(b)/v)(a + igamma(5)b) parameterization of the Hb (b) over bar interaction. This process is shown to be highly sensitive to this coupling constant. Experiments at the future with roots = 500-GeV linear collider will provide limits of 2 and 20% for deviations of the parameters a and b, respectively, from their Standard Model values. Results concerning the e(+)e(-)-->b (b) over bar nu(ν) over bar process in combination with the independent measurements of the partial width Gamma(H --> b (b) over bar) can testify to the CP origin of the Higgs sector of the theory. (C) 2003 MAIK Nauka/Interperiodica.

Cosmological constant and the speed of light

By exploring the relationship between the propagation of electromagnetic waves in a gravitational field and the light propagation in a refractive medium, it is shown that, in the presence of a positive cosmological constant, the velocity of light will be smaller than its special relativity value. Then, restricting again to the domain of validity of geometrical optics, the same result is obtained in the context of wave optics. It is argued that this phenomenon and the anisotropy in the velocity of light in a gravitational field are produced by the same mechanism.

Freezing of the QCD coupling constant and solutions of Schwinger-Dyson equations

We compare phenomenological values of the frozen QCD running coupling constant (alpha(s)) with two classes of infrared finite solutions obtained through nonperturbative Schwinger-Dyson equations. We use these same solutions with frozen coupling constants as well as their respective nonperturbative gluon propagators to compute the QCD prediction for the asymptotic pion form factor. Agreement between theory and experiment on alpha(s)(0) and F (pi)(Q(2)) is found only for one of the Schwinger-Dyson equation solutions.

Differential and partial cross sections of elastic and inelastic positronium-helium-atom scattering

Scattering of positronium (Ps) by a helium atom has been investigated in a three-Ps-state coupled-channel model including Ps(1s,2s,2p) states using a recently proposed time-reversal-symmetric regularized electron-exchange model potential. Specifically, we report results of differential cross sections for elastic scattering and target-elastic Ps excitations. We also present results for total and different partial cross sections and compare them with experiment and other calculations.

Close-coupling calculations of elastic and inelastic positron-helium scattering

Elastic and inelastic positron-helium scattering have been investigated in different partial waves at medium energies using the close-coupling approximation with realistic wavefunctions employing the following states: He(1s1s), He(1s2s), He(1s2p), He(1s3s), He(1s3p), Ps(1s), Ps(2s) and Ps(2p). All excitations of the helium atom are in the spin-singlet electronic state. Calculations are reported of cross sections to He(1s1s), He(1s2s), and He(1s2p) transitions for incident positron energies up to 200 eV. These cross sections are in good agreement with experimental results.

Aspects of a dynamical gluon mass approach to elastic hadron scattering at LHC

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

QCD tests with an infrared finite gluon propagator and coupling constant

Recent progress in the solution of Schwinger-Dyson equations, as well as lattice simulation of pure glue QCD, indicate that the gluon propagator and coupling constant are infrared finite. Such non-perturbative information can be introduced in the QCD perturbative expansion in the scheme named Dynamical Perturbation Theory. We exemplify this procedure with the calculation of some two-body non-leptonic annihilation B meson decays, which show agreement with the experimental data in the case of a gluon propagator characterized by a dynamical gluon mass of 500MeV, compatible with the value found in several processes computed with this method. We give a. preliminary account of the application of this procedure at the loop level in the case of the Bjorken sum rule.

LIMITS on THE COUPLING CONSTANT of HIGHER-DERIVATIVE ELECTROMAGNETISM

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Determination of the strong coupling constant from the inclusive jet cross section in pp collisions at s=1.96 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A comparative study of the low energy HD plus o-/p-H-2 rotational excitation/de-excitation collisions and elastic scattering

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ultracold collisions between two light indistinguishable diatomic molecules: Elastic and rotational energy transfer in HD plus HD

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Weak decay constant of pseudoscalar mesons in a QCD-inspired model

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Stability of differential equations with piecewise constant argument via discrete equations

Lyapunov stability for a class of differential equation with piecewise constant argument (EPCA) is considered by means of the stability of a discrete equation. Applications to some nonlinear autonomous equations are given improving some linear known cases.

A polaronic stacking fault defect model for CaCu3Ti4O12 material: an approach for the origin of the huge dielectric constant and semiconducting coexistent features

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)