Inclusion of W^+- single-spin asymmetry data in a polarised PDF determination via Bayesian reweighting

We discuss how the experimental information from longitudinal single-spin asymmetries for $W^{\pm}$ boson production in polarised proton-proton collisions can be included in a polarised parton determination by Bayesian reweighting of a Monte Carlo set of polarised PDF replicas. We explicitly construct a prior ensemble of polarised parton distributions using available fits to inclusive and semi-inclusive DIS data and we discuss the potential impact of existing and future RHIC measurements on it.Comment: 5 pages, 4 figures, to appear in the proceedings of the 3rd Workshop on the QCD Structure of the Nucleon (QCD-N'12), Bilbao October 201

Fragmentation functions of charged hadrons

I present a preliminary determination of the Fragmentation Functions (FFs) of unidentified charged hadrons at next-to-leading order in quantum chromodynamics. The analysis is based on hadron production cross section data in single-inclusive electron-positron annihilation. It extends a recent determination of the FFs of identified charged pions, charged kaons and protons/antiprotons performed by the NNPDF Collaboration. I illustrate the quality of the FFs determined in this analysis and show how they describe the charged hadron spectra measured in proton-(anti)proton collisions.Comment: 5 pages, 3 figures, 1 table, contribution to the proceedings of the XXV Workshop on Deep-Inelastic Scattering and related Subjects (DIS2017

Flavor asymmetry of the polarized nucleon sea

We discuss the flavor asymmetry of polarized light antiquarks in the nucleon, $\Delta\bar{u}-\Delta\bar{d}$. We present a determination of this quantity based on two global QCD analyses of experimental data, DSSV08 and NNPDFpol1.1, in which sea-quark parton distribution functions are determined respectively either from semi-inclusive deep-inelastic scattering or W-boson production data. The latter have become available only very recently, and their effect on the polarized flavor asymmetry is presented here for the first time. We find that the flavor asymmetry of polarized antiquarks in the nucleon is definitely positive, and has almost the same absolute size as its unpolarized counterpart. We compare this result with various theoretical models of the nucleon structure in order to test their validity. We show that some of them are clearly disfavored.Comment: 6 pages, 2 figures, 1 table, contribution to the proceedings of DIS2014, Apr 28-May 2, Warsaw, Polan

Small- and large-x nucleon spin structure from a global QCD analysis of polarized Parton Distribution Functions

I investigate the behavior of spin-dependent parton distribution functions in the regions of small and large momentum fractions $x$. I present a systematic comparison between predictions for relevant observables obtained with various models of nucleon spin structure and a recent global analysis of spin-dependent distributions, NNPDFpol1.1. Together with its unpolarized counterpart, NNPDF2.3, they form a mutually consistent set of parton distributions. Because they include most of the available experimental information, and are determined with a minimally biased methodology, these are especially suited for such a study. I show how NNPDFpol1.1 can discriminate between different theoretical models, even though NNPDF uncertainties remain large near the endpoints $x\to 0$ and $x\to 1$, due to the lack of experimental information. I discuss how our knowledge of nucleon spin structure may be improved at small-$x$ by future measurements at an Electron-Ion Collider, and at large-$x$ by recent measurements at Jefferson Lab, also in view of its $12$ GeV upgrade.Comment: 10 pages, 6 figures, version to be published in Phys.Lett.

Constraints on polarized parton distributions from open charm and W production data

We study the impact of new open charm muoproduction data from COMPASS and preliminary W production data from STAR on NNPDFpol1.0, the first unbiased set of polarized parton distributions recently delivered by the NNPDF Collaboration and based on inclusive Deep-Inelastic Scattering data only. The information contained in the new data sets is incorporated in our Monte Carlo parton determination via Bayesian reweighting, a method based on statistical inference which avoids the need for a global refitting. We explicitly show to which extent COMPASS and STAR data can improve our knowledge of gluon and antiquark polarized parton distributions respectively.Comment: 6 pages, 3 figures, to appear in the proceedings of the XXI International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS2013), Marseille, 22-26 April 201

Virtual Environments as Spaces of Symbolic Construction and Cultural Identity. Latin-American Virtual Communities

The aim of this work is to understand the sociopsychological\ud and cultural realities of virtual communities as live spaces of meeting and high interaction framed within the Latin American context. The study will consist of a comparative ethnographic study of several Latin communities, using the tools of participant observation and focused interviews