Proton Compton scattering and photoproduction of vector mesons at high energies are studied in terms of the quark model. It is shown that under the vector meson dominance hypothesis the quark model gives the rP total hadronic cross section in good agreement with the experimental data. The real-to-imaginary ratio of forward proton Compton scattering is related to the total cross sections and the...

We apply the Low's theorem to soft gluon emission from heavy quark scattering in nonperturbative strongly interacting quark-gluon plasma (sQGP). The sQGP is described terms of dynamical quasi-particles and adjusted reproduce EoS lQCD at finite temperature chemical potential. Since emitted long wavelength, it does not provide information on detailed structure scattering, only incoming outgoing p...

In these lectures I want to discuss how the structure functions in deep inelastic scattering relate to quark and gluon correlation functions. In particular we will consider the issue of intrinsic transverse momenta of quarks, which becomes important in processes like 1-particle inclusive leptoproduction. Some examples of cross sections and asymmetries, in particular in polarized scattering proc...

We discuss shadowing corrections to the structure function F2 in neutrino deep-inelastic scattering on heavy nuclear targets. In particular, we examine the role played by shadowing in the comparison of the structure functions F2 measured in neutrino and muon deep inelastic scattering. The importance of shadowing corrections in the determination of the strange quark distributions

We comment on some implications of theories with large compactification radii and TeV-scale quantum gravity. These include the behavior of high-energy gravitational scattering cross sections and consequences for ultrahigh-energy cosmic rays and neutrino scattering, the question of how to generate naturally light neutrino masses, the issue of quark-lepton unification, the equivalence principle, ...

The impact of virtual leptoquark or R-parity breaking squark exchange as well as generic contact interactions on the production of quark–antiquark pairs in ee annihilation, in particular at LEP2, is summarized. An exciting possibility of sneutrino formation in ee scattering is also mentioned. Talk presented at the 5th International Workshop on “Deep Inelastic Scattering and QCD” (DIS ’97), Chic...

It has been recently found that the heavy quark-antiquarkQQ̄ pair multiplicity, in certain phase space region (QQ̄ at short distance, soft and with small velocity), satisfies an evolution equation formally similar to the BFKL equation for the high energy scattering amplitude. We find the exact solution of the QQ̄-equation and discuss the differences with the BFKL scattering amplitude

In the physical vacuum of QCD, the energy density of lightquark fields strongly coupled to slowly varying gluon fields can be negative. The states that drive this energy density lowest are condensates of pairs of quarks and antiquarks of nearly opposite momenta. These quark-antiquark condensates break chiral symmetry.

This review covers selected results from the LEP experiments on the structure of quasi-real and virtual photons. The topics discussed are the total hadronic cross-section for photon-photon scattering, hadron production, jet cross-sections, heavy quark production for photon-photon scattering, photon structure functions, and crosssections for the exchange of two virtual photons.

We derive new positivity constraints on the spin-dependent structure functions of the nucleon. These model independent results reduce considerably their domain of allowed values, in particular for the chiral-odd parton distribution h1(x). PACS Numbers : 12.90+b, 12.40.Aa, 13.88+e Key-Words : Positivity, polarized quark distributions. Number of figures : 3 September 1994 CPT-94/P.3059 anonymous ...