7,624 research outputs found
Global Analysis of Fragmentation Functions for Protons and Charged Hadrons
We present new sets of fragmentation functions for protons and inclusive
charged hadrons obtained in combined NLO QCD analyses of single-inclusive
hadron production in electron-positron annihilation, proton-proton collisions,
and deep-inelastic lepton-proton scattering. These analyses complement previous
results for pion and kaon fragmentation functions with charge and flavor
discrimination. The Lagrange multiplier technique is used to assess the
uncertainties in the extraction of the new sets of fragmentation functions.Comment: 14 pages, 14 figure
Evidence for polarization of gluons in the proton
We discuss the impact of recent high-statistics RHIC data on the
determination of the gluon polarization in the proton in the context of a
global QCD analysis of polarized parton distributions. We find clear evidence
for a non-vanishing polarization of gluons in the region of momentum fraction
and at the scales mostly probed by the data. Although information from low
momentum fractions is presently lacking, this finding is suggestive of a
significant contribution of gluon spin to the proton spin, thereby limiting the
amount of orbital angular momentum required to balance the proton spin budget.Comment: 5 pages, 5 eps figure
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