We investigate the Q evolution of parton distributions at small x values, obtained in the case of flat initial conditions. The contributions of twist-two and (renormalontype) higher-twist operators of the Wilson operator product expansion are taken into account. The results are in excellent agreement with deep inelastic scattering experimental data from HERA. Key-words: Quantum Chromodynamics, ...

The first measurements of the cross sections for neutral and charged current deep inelastic scattering in ep collisions with longitudinally polarised positron beams are presented. The total cross section for ep charged current deep inelastic scattering is presented at positive and negative values of positron beam longitudinal polarisation for an integrated luminosity of 37.0 pb H1 data and 30.5...

We analyze longitudinal beam and target single-spin asymmetries in semi-inclusive deep inelastic scattering and in jet deep inelastic scattering, including all possible twist-3 contributions as well as quark mass corrections. We take into account the path-ordered exponential in the soft correlators and show that it leads to the introduction of a new distribution and a new fragmentation function...

We reanalyze deep inelastic scattering data of BCDMS Collaboration by including proper cuts of ranges with large systematic errors. We perform also the fits of high statistic deep inelastic scattering data of BCDMS, SLAC, NM and BFP Collaborations taking the data separately and in combined way and find good agreement between these analyses. We extract the values of both the QCD coupling constan...

We reanalyze deep inelastic scattering data of BCDMS Collaboration by including proper cuts of ranges with large systematic errors. We perform also the fits of high statistic deep inelastic scattering data of BCDMS, SLAC, NM and BFP Collaborations taking the data separately and in combined way and find good agreement between these analyses. We extract the values of both the QCD coupling constan...

The scalar and vector leptoquark pair production cross sections for deep inelastic ep scattering are calculated. Estimates are presented for the search potential at HERA. Contribution to the Proceedings of the 1996 HERA Physics Workshop Leptoquark Pair Production at HERA Johannes Blümlein, Edward Boos, and Alexander Kryukov a DESY–Zeuthen, Platanenallee 6, D-15735 Zeuthen, Germany b Institute o...

The phenomenon of scaling in deep inelastic lepton-nucleon scattering is usually explained in terms of the Feynman parton model, and the logarithmic corrections to scaling are explained in the framework of perturbative QCD. For testing the validity of the parton model, we consider the deep inelastic electron scattering in a model in which the system electromagnetic current operator explicitly s...

The perturbative QCD predictions concerning deep inelastic scattering at low x are summarized. The theoretical framework based on the leading log 1/x re-summation and k t factorization theorem is described and some recent developments concerning the BFKL equation and its generalization are discussed. The QCD expectations concerning the small x behaviour of the spin dependent structure function ...

We discuss bounds on the distribution and fragmentation functions that appear at leading order in deep inelastic 1-particle inclusive leptoproduction or in Drell-Yan processes. These bounds simply follow from positivity of the quarkhadron scattering matrix elements and are an important guide in estimating the magnitude of the azimuthal and spin asymmetries in these processes. We focus on an exa...

Hadronic interactions are successfully parameterized in different models. Those most frequently applied are the Regge parameterization and the geometrical model. In the present paper we want to apply the geometrical picture to different domains of the hadronic interaction. The model used is a very economical model in that it contains only few parameters most of which have a direct physical inte...