Related papers: Hard Scattering in QCD with Polarized Beams
We discuss some problems concerning the application of perturbative QCD to high energy processes. In particular for hard processes, we analyze higher order and higher twist corrections. It is argued that these effects are of great…
With the increasing experimental precision available at colliders, higher-order perturbative calculations are required to reduce the theory uncertainty in order to extract crucial QCD parameters, such as the strong coupling constant, to the…
We present a decomposition of the hadronic tensor for a general polarized Drell-Yan process AB --> l^+ l^- X in terms of helicity structure functions using the helicity axes of the dilepton rest frame as a basis. Next, we consider a QCD…
Hadronic diffractive processes characterised by a hard scale (hard diffraction) contain a nontrivial interplay of hard and soft, nonperturbative interactions, which breaks down factorisation of short and long distances. On the contrary to…
General arguments suggest that the non-perturbative background field in QCD may have a non-trivial spin structure. We discuss how this effect may be manifest in semi-inclusive measurements of fast pions in polarised deep inelastic…
In order to determine polarized parton distributions we have made a new NLO QCD fit using all experimental data on spin asymmetries measured in the deep inelastic scattering on different nucleon targets. The functional form of such…
We investigate the inclusive production of prompt J/psi mesons in polarized hadron-hadron and photon-hadron collisions in the factorization formalism of NRQCD. Numerical results are presented for BNL RHIC-Spin and the approved SLAC…
The hadronization of a high-energy parton is described by fragmentation functions which are introduced through QCD factorizations. While the hadronization mechanism per se remains uknown, fragmentation functions can still be investigated…
Motivated by the need to correct the potentially large kinematic errors in approximations used in the standard formulation of perturbative QCD, we reformulate deeply inelastic lepton-proton scattering in terms of gauge invariant, universal…
A QCD analysis of the world data on polarized deep inelastic scattering is presented in leading and next-to-leading order. New parameterizations are derived for the quark and gluon distributions for the kinematic range $x \epsilon…
I discuss inclusive and semi-inclusive lepton-hadron scattering emphasizing the importance of polarization in order to study various single or double spin asymmetries and the importance of particle identification and angular resolution in…
We calculate and analize the ${\cal{O}}(\alpha_s)$ one-particle inclusive cross section in polarized deep inelastic lepton-hadron scattering, using dimensional regularization and the HVBM prescription for $\gamma_5$. We discuss the…
We study the phenomenon of parton-hadron duality in both polarised and unpolarised electron proton scattering using the HERMES and the Jefferson Lab data, respectively. In both cases we extend a systematic perturbative QCD based analysis to…
We demonstrate that the multipoles associated with the density matrix are truly observable quantities that can be unambiguously determined from intensity moments. Given their correct transformation properties, these multipoles are the…
Factorization theorem plays the central role at high energy colliders to study standard model and beyond standard model physics. The proof of factorization theorem is given by Collins, Soper and Sterman to all orders in perturbation theory…
Quantum Chromodynamics (QCD) is a firmly established part of the Standard Model, yet its long distance properties remain challenging at a conceptual level. In recent years significant experimental and theoretical progress has been made…
Modern-day `testing' of (perturbative) QCD is as much about pushing the boundaries of its applicability as about the verification that QCD is the correct theory of hadronic physics. This talk gives a brief discussion of a small selection of…
We compare the numerical predictions for heavy quark production in high energy hadron collisions of the conventional QCD parton model and the $k_T$-factorization approach (semihard theory). The total production cross sections, one-particle…
A continuing mystery in particle physics is the large polarization observed in inclusive hyperon production in high energy p-p collisions. In this paper the authors advance the concept that the polarization effects can be accounted for in a…
There has been much recent research into possible methods of polarizing an antiproton beam, the most promising being spin filtering, the theoretical understanding of which is currently incomplete. The method of polarization buildup by spin…