Spin structure function of the virtual photon

We investigate the spin structure of the virtual photon beyond the leading order in QCD. The first moment of the virtual photon spin structure function $g_1^\gamma(x,Q^2,P^2)$ with QCD effects turns out to be non-vanishing in contrast to the real photon case. Numerical analysis for virtual as well as real photon case is presented.Comment: 3 pages, LaTeX, 3 ps figures, uses npb.sty, Contribution to the Workshop on Deep Inelastic Scattering and QCD (DIS 99), Zeuthen, April 199

The structure functions of longitudinal virtual photon at low virtualities

The structure functions of longitudinal virtual photon at low virtualities are calculated in the framework of chiral pertubation theory(ChPT) in the zero and first order of ChPT. It is assumed that the virtuality of target longitudinal photon is much less than the virtuality of the hard projectile photon and both are less than the characteristic ChPT scale.Comment: 16 pages, 8 figure

Comparison of NNLO DIS scheme splitting functions with results from exact gluon kinematics at small x.

We consider the effect of exact gluon kinematics in the virtual photon-gluon impact factor at small x. By comparing with fixed order DIS scheme splitting and coefficient functions, we show that the exact kinematics results match the fixed order results well at each order, which suggests that they allow for an accurate NLL analysis of proton structure functions. We also present, available for the first time, x-space parameterisations of the NNLO DGLAP splitting functions in the DIS scheme, and also the longitudinal coefficients for neutral current scattering

Improving Physics learning with virtual environments: an example on the phases of water

Usually students have misconceptions on the microscopic structure and behaviour of matter. In order to overcome these difficulties computer-based worlds seem useful to visualize physical and chemical processes allowing for a better conceptual understanding. Since more 3-D virtual environments need to be explored and evaluated in science education, we have built a 3-D virtual environment – “Virtual Water” – to support the learning of Physics and Chemistry at the final high school and first-year university levels. It is centered in the microscopic structure of water and explores concepts related to water phases and the transitions between them.Usually students have misconceptions on the microscopic structure and behaviour of matter. In order to overcome these difficulties computer-based worlds seem useful to visualize physical and chemical processes allowing for a better conceptual understanding. Since more 3-D virtual environments need to be explored and evaluated in science education, we have built a 3-D virtual environment – “Virtual Water” – to support the learning of Physics and Chemistry at the final high school and first-year university levels. It is centered in the microscopic structure of water and explores concepts related to water phases and the transitions between them

Improving Physics learning with virtual environments: an example on the phases of water

Usually students have misconceptions on the microscopic structure and behaviour of matter. In order to overcome these difficulties computer-based worlds seem useful to visualize physical and chemical processes allowing for a better conceptualunderstanding. Since more 3-D virtual environments need to be explored and evaluatedin science education, we have built a 3-D virtual environment – “Virtual Water” – tosupport the learning of Physics and Chemistry at the final high school and first-yearuniversity levels. It is centered in the microscopic structure of water and exploresconcepts related to water phases and the transitions between them.Usually students have misconceptions on the microscopic structure and behaviour of matter. In order to overcome these difficulties computer-based worlds seem useful to visualize physical and chemical processes allowing for a better conceptualunderstanding. Since more 3-D virtual environments need to be explored and evaluatedin science education, we have built a 3-D virtual environment – “Virtual Water” – tosupport the learning of Physics and Chemistry at the final high school and first-yearuniversity levels. It is centered in the microscopic structure of water and exploresconcepts related to water phases and the transitions between them

Electron-phonon interaction in Fe-based superconductors: Coupling of magnetic moments with phonons in LaFeAsO1−x_{1-x}Fx_{x}

The coupling of Fe magnetic moments in LaFeAsO$_{1-x}$F$_{x}$ with the As $A_{1g}$ phonon is calculated. We present first principles calculations of the atomic and electronic structure of LaFeAsO as a function of electron doping. We perform calculations using the virtual crystal approximation as well as supercell calculations with F substitutional impurity atoms. The results validate the virtual crystal approximation for the electronic structure near the Fermi level. Its is found that the electronic density of states at the Fermi level is maximum for x=0.125, enhancing the electron-phonon interaction. An additional increase of the electron-phonon parameter $\lambda$ is obtained if the coupling between the $A_{1g}$ phonon and the Fe magnetic moment is included. It is found that the electron-phonon interaction can be one order of magnitude larger than its value if no spin resolution is included in the calculation. The implications of these results on the superconducting transition are discusse