Consistency in NLO analyses of inclusive and semi-inclusive polarized DIS data

We perform a detailed study of the consistency between different sets of polarized deep inelastic scattering data and theory, from the standpoint of a next to leading order QCD global analysis, and following the criteria proposed by Collins and Pumplin. In face of recent suggestions that challenge the usual assumption about parent parton spin independence of unpolarized fragmentation functions, we specially focus on polarized semi-inclusive data.Comment: 17 pages, 5 figure

Constraints on gluon polarization in the nucleon at NLO accuracy

We compare constraints on the gluon polarization in the nucleon obtained in next to leading order global QCD fits to polarized deep inelastic scattering data with those coming from observables more directly linked to the gluon polarization, such as the double spin asymmetry measured by Phenix at RHIC, and high-pT hadron production studied by COMPASSComment: 4 pages, 3 figures, 1 tabl

Target Fragmentation and Fracture Functions

We analyse recent data on the production of forward neutrons in deep inelastic scattering at HERA in the framework of a perturbative QCD description for semi-inclusive processes, which includes fracture functions.Comment: To be published in Proceedings of the Madrid low-x Workshop, Miraflores de la Sierra, June 18-21, 199

Deep inelastic scattering, diffraction, and all that

These lectures include an introduction to the partonic description of the proton, the photon and the `colour singlet', as seen in inclusive and semi-inclusive DIS, in $e^+e^-$ collisions, and in diffractive processes, respectively. Their formal treatment using structure, fragmentation, and fracture functions is outlined giving an insight into the perturbative QCD framework for these functions. Examples and comparisons with experimental data from LEP, HERA, and Tevatron are also covered.Comment: 46 pages, 52 postscript figures, LaTeX, aipproc.sty. To be published in the proceedings of VII Mexican Workshop on Particles and Field

Unveiling the Proton Spin Decomposition at a Future Electron-Ion Collider

We present a detailed assessment of how well a future Electron-Ion Collider could constrain helicity parton distributions in the nucleon and, therefore, unveil the role of the intrinsic spin of quarks and gluons in the proton's spin budget. Any remaining deficit in this decomposition will provide the best indirect constraint on the contribution due to the total orbital angular momenta of quarks and gluons. Specifically, all our studies are performed in the context of global QCD analyses based on realistic pseudo-data and in the light of the most recent data obtained from polarized proton-proton collisions at BNL-RHIC that have provided evidence for a significant gluon polarization in the accessible, albeit limited range of momentum fractions. We also present projections on what can be achieved on the gluon's helicity distribution by the end of BNL-RHIC operations. All estimates of current and projected uncertainties are performed with the robust Lagrange multiplier technique.Comment: 12 pages, 8 eps figure

Extraction of polarized parton densities from polarized DIS and SIDIS

We present results on the quark and gluon polarization in the nucleon obtained in a combined next to leading order analysis to the available inclusive and semi-inclusive polarized deep inelastic scattering data.Comment: Talk given at XIII International Workshop on Deep Inelastic Scattering, April,27 - May,1, 2005, Madison, Wisconsin, USA, 4 pages, 2 figure

Sea quark and gluon polarization in the nucleon at NLO accuracy

We investigate the sea quark polarization in the nucleon by means of a combined next to leading order analysis to the recently enlarged set of inclusive and semi-inclusive polarized deep inelastic scattering data. Using the Lagrange multiplier method, we asses the uncertainty inherent to the extraction of the different spin dependent parton densities in a QCD global fit, and the impact of the increased set of semi-inclusive data now available. We comment on future prospects at RHIC and JLAB and their potential impact in the future determination of polarized parton densities.Comment: 15 pages, 9 figures, 3 table

NLO Scale Dependence of Semi-Inclusive Processes

We discuss the order \alpha_s^2 gluon initiated QCD corrections to one particle inclusive deep inelastic processes. We focus in the NLO evolution kernels relevant for the non homogeneous QCD scale dependence of these cross sections and factorization.Comment: Poster presentation at the XXIII Physics in Collision Conference (PIC03), Zeuthen, Germany, June 2003, 3 pages, LaTeX, 4 eps figures, PSN FRAP1