The decay ρ0→π0π0γ\rho^{0}\to \pi^{0}\pi^{0}\gamma and the role of σ\sigma-meson

We study the radiative decay $\rho^{0}\to\pi^{0}\pi^{0}\gamma$ within the framework of a phenomenological approach in which the contributions of $\sigma$-meson and $\omega$-meson intermediate states and of the pion-loops are considered. We conclude that the $\sigma$-meson amplitude provides the dominant contribution.Comment: 12 pages, LATEX, 3 PS figure

The ϕa0γ\phi a_0\gamma- and ϕσγ\phi\sigma\gamma-vertices in light cone QCD

We study $\phi a_0\gamma$- and $\phi\sigma\gamma$-vertices in the framework of the light cone QCD sum rules and we estimate the coupling constants g$_{\phi a_0\gamma}$ and g$_{\phi\sigma\gamma}$ utilizing $\omega\phi$-mixing. We compare our results with the previous estimations of these coupling constants in the literature obtained from phenomenological considerations.Comment: 8 pages, RevTex, 2 figure

The a0K+K−a_0K^+K^--vertex in light cone QCD sum rules

We investigate the $a_0K^+K^-$-vertex in the framework of light cone QCD sum rules. We estimate the coupling constant g$_{a_0K^+K^-}$ which is an essential ingredient in the analysis of physical processes involving $a_0(980)$ meson. Our result is somewhat larger than the previous determinations of this coupling constant.Comment: 8 pages, 1 figur

The ωσγ\omega\sigma\gamma-vertex in light cone QCD sum rules

We investigate the $\omega\sigma\gamma$-vertex and estimate the coupling constant g$_{\omega\sigma\gamma}$ in the framework of the light cone QCD sum rules. We compare our result with the values of this coupling constant deduced from a phenomenological analysis of $\omega\to\pi\pi\gamma$ decays.Comment: 5 pages, RevTex, 1 Figur

The coupling constants g_{\rho\pi\gamma} and g_{\omega\pi\gamma} as derived from QCD sum rules}

We employ QCD sum rules to calculate the coupling constants g$_{\rho\pi\gamma}$ and g$_{\omega\pi\gamma}$ by studying the three point ${\rho\pi\gamma}$- and ${\omega\pi\gamma}$-correlation functions. Our results for the decay widths $\Gamma(\rho^0\to \pi^0\gamma)$ and $\Gamma(\omega\to \pi^0\gamma)$ calculated using the obtained coupling constants are in good agreement with the experimental values of these decay widths

Collisional Effects in Isovector Response Function of Nuclear Matter at Finite Temperature

The dipole response function of nuclear matter at zero and finite temperatures is investigated by employing the linearized version of the extended TDHF theory with a non-Markovian binary collision term. Calculations are carried out for nuclear dipole vibrations by employing the Steinwedel-Jensen model and compared with experimental results for $^{120}Sn$ and $^{208}Pb$.Comment: 14 pages, RevTex, 3 PS figure

Collisional Damping of Giant Monopole and Quadrupole Resonances

Collisional damping widths of giant monopole and quadrupole excitations for $^{120}$Sn and $^{208}$Pb at zero and finite temperatures are calculated within Thomas-Fermi approximation by employing the microscopic in-medium cross-sections of Li and Machleidt and the phenomenological Skyrme and Gogny forces, and are compared with each other. The results for the collisional widths of giant monopole and quadrupole vibrations at zero temperature as a function of the mass number show that the collisional damping of giant monopole vibrations accounts for about 30-40% of the observed widths at zero temperature, while for giant quadrupole vibrations it accounts for only 20-30% of the observed widths of zero temperature.Comment: RevTex, 12 pages, 6 PS figure

Evaluation of social personalized adaptive E-Learning environments : end-user point of view

The use of adaptations, along with the social affordances of collaboration and networking, carries a great potential for improving e-learning experiences. However, the review of the previous work indicates current e-learning systems have only marginally explored the integration of social features and adaptation techniques. The overall aim of this research, therefore, is to address this gap by evaluating a system developed to foster social personalized adaptive e-learning experiences. We have developed our first prototype system, Topolor, based on the concepts of Adaptive Educational Hypermedia and Social E-Learning. We have also conducted an experimental case study for the evaluation of the prototype system from different perspectives. The results show a considerably high satisfaction of the end users. This paper reports the evaluation results from end user point of view, and generalizes our method to a component-based evaluation framework

On growth of spinodal instabilities in nuclear matter-II:asymmetric matter

As an extension of our previous work, the growth of density fluctuations in the spinodal region of charge asymmetric nuclear matter is investigated in the basis of the stochastic mean-field approach in the non-relativistic framework. A complete treatment of density correlation functions are presented by including collective modes and non-collective modes as well.Comment: 20 pages, 6 figures, Accepted by Physical Review