Implication of the overlap representation for modelling generalized parton distributions

Based on a field theoretically inspired model of light-cone wave functions, we derive valence-like generalized parton distributions and their double distributions from the wave function overlap in the parton number conserved s-channel. The parton number changing contributions in the t-channel are restored from duality. In our construction constraints of positivity and polynomiality are simultaneously satisfied and it also implies a model dependent relation between generalized parton distributions and transverse momentum dependent parton distribution functions. The model predicts that the t-behavior of resulting hadronic amplitudes depends on the Bjorken variable x_Bj. We also propose an improved ansatz for double distributions that embeds this property.Comment: 15 pages, 8 eps figure

O₂ Adsorption Dynamics at Metal Surfaces: Non-adiabatic Effects, Dissociation and Dissipation

We review recent progress in the theoretical description of the O2 adsorption dynamics at metal surfaces. Intriguing conceptual challenges to a quantitative modeling arise from the spin triplet ground state of the free oxygen molecule, the typically highly corrugated potential energy surfaces (PESs), and the high exothermicity of dissociative adsorption processes. This dictates extensive dynamical simulations (either through direct ab initio molecular dynamics or PES interpolating divide and conquer approaches), an account of electronic non- adiabaticity, as well as heat dissipation channels. We critically discuss the present status of corresponding methodology and the physical insight gained through it, using the oxygen adsorption at Al(111), Pt(111), Pt(211) and Pd(100) as showcases