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The reactions e + e − → π + π − and e + e − → N N with N = p, n are studied in a non-perturbative quark model. The work suggests that the two-step process, in which the primary qq pair forms first a vector meson which in turn decays into a hadron pair, is dominant over the one-step process in which the primary qq pair is directly dressed by additional qq pairs to form a hadron pair. To reproduce the experimental data of the reaction e + e − → nn and pp a D-wave ω-like vector meson with a mass of around 2 GeV has to be introduced.

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PACS 61.50. Ah, 61.66.Fn, 61.72.Ji, 71.15.Nc, 71.20.Ps Ab-initio electronic structure calculations using the local density (LDA) and generalized gradient approximations (GGA) are undertaken on Potassium Titanyl Phosphate (KTP) and isomorphic materials. The crystal structure is better predicted using one of the GGA approximations. The affect of Rb replacing K on the essential TiO 6 and PO 4 blocks of the alloyed system are investigated as are affects of AsO 4 replacing PO 4 . It is observed that the asymmetry in the K -Rb alloy very slightly affects the electronic properties of the material. Electronic charge density distributions clearly show the cation conduction channels, with changes found to occur between the different structural isomorphs. A calculated density of electronic states shows the importance of Ti -O interactions around the Fermi energy that lead to important laser properties.