In order to study the end-point spectrum of inclusive semileptonic b → u decays, we investigate the parton model motivated by deep inelastic scattering process. The reliability of the model is carefully examined by comparing the decay rates and the lepton spectra for b → c decay with those of the heavy quark effective theory. We also compute the decay rates of the inclusive semileptonic decay i...

The evolution of orbital angular momentum distributions within the radiative parton model is studied. We use different scenarios for the helicity weighted parton distributions and consider a broad range of input distributions for orbital angular momentum. In all cases we are lead to the conclusion that the absolute value of the average orbital angular momentum per parton peaks at relatively lar...

We study infrared contributions to semihard parton-parton interactions by considering an effective charge whose finite infrared behavior is constrained by a dynamical mass scale. Using an eikonal QCDbased model in order to connect this semihard parton-level dynamics to the hadron-hadron scattering, we obtain predictions for the proton-proton (pp) and antiproton-proton (p̄p) total cross sections,...

We give an overview of the theory for generalized parton distributions. Topics covered are their general properties and physical interpretation, the possibility to explore the three-dimensional structure of hadrons at parton level, their potential to unravel the spin structure of the nucleon, their role in small-x physics, and efforts to model their dynamics. We review our understanding of the ...

V NI is a general-purpose Monte-Carlo event-generator, which includes the simulation of lepton-lepton, lepton-hadron, lepton-nucleus, hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions. On the basis of renormalization-group improved parton description and quantum-kinetic theory, it uses the real-time evolution of parton cascades in conjunction with a self-consistent hadronization sch...

Multiple parton scatterings inside a large nucleus generally involve higher twist nuclear parton matrix elements The gluon bremsstrahlung induced by multiple scattering depends not only on direct parton matrix elements but also on momentum crossed ones due to the Landau Pomeranchuk Migdal in terference e ect We show that both types of twist four nuclear parton matrix elements can be factorized ...

General physics of very high energy hadronic interactions is discussed. Special attention is payed to the contribution of semihard processes to the interaction dynamics and to the role of parton shadowing and parton density saturation. In particular, the implementation of non-linear interaction effects in the QGSJET-II model is discussed in detail. The predictions of the model are compared to s...

The parton model is applicable to large momentum transfer hadronic processes. Scaling in hadronic cross-sections is interpreted in the parton model as a consequence of the existence of charged pointlike constituents in hadrons. Parton model cross-sections are calculated by combining amplitudes for the scattering of these constituents with probability densities (parton distribution functions) fo...

We calculate the hadron spectra in high-energy pp, pA and AA collisions within a pQCD parton model. Analyses of experimental data show that the modification of the spectra in pA and AA as compared to that in pp collisions is consistent with multiple parton scattering scenario and is dictated by the transition from absorptive soft interaction at low pT to incoherent hard parton scattering at hig...

We propose a modiication of the equivalent photon approximation (EPA) for processes which involve the parton content of the photon, to take into account the suppression of the photonic parton uxes due to the virtuality of the photon. We present simple, physically motivated anss atze to model this suppression and show that even though the parton content of the electron no longer factorizes into ...