Proton-proton correlations at small relative momentum in neon-nucleus collisions at E/A=400 and 800 MeV

Proton-proton small angle correlations have been measured in neon-nucleus collisions, using the 4 pi detector Diogene, at 400 and 800 MeV per nucleon incident energies. Values of the size of the emitting region are obtained by comparison with the Koonin formula, taking into account the biases of the apparatus. The dependence of the density on target mass and incident energy is also analysed.     

Photon gluon fusion cross sections at HERA energy

We present cross sections for heavy flavour production through photon gluon fusion in electron proton collisions at HERA energy. The electron photon vertex is taken into account explicitly, and theQ ² of the exchanged photon ranges from nearly zero (almost real photon) to the kinematically allowed maximum. In our approach the scale is set by the mass of the produced quarks. Our formalism is also applicable to the production of light quarks as long as the invariant mass of the pair is sufficiently high, so we also give cross sections for \(u\bar u,d\bar d\) and \(s\bar s\) production.