21 research outputs found
QCD resummation for semi-inclusive hadron production processes
We investigate the resummation of large logarithmic perturbative corrections
to hadron production in electron-positron annihilation and semi-inclusive
deep-inelastic scattering. We find modest, but significant, enhancements of
hadron multiplicities in the kinematic regimes accessible in present
high-precision experiments. Our results are therefore relevant for the
determination of hadron fragmentation functions from data for these processes.Comment: 14 pages, 11 figure
Fragmentation Functions Beyond Fixed Order Accuracy
We give a detailed account of the phenomenology of all-order resummations of
logarithmically enhanced contributions at small momentum fraction of the
observed hadron in semi-inclusive electron-positron annihilation and the
time-like scale evolution of parton-to-hadron fragmentation functions. The
formalism to perform resummations in Mellin moment space is briefly reviewed,
and all relevant expressions up to next-to-next-to-leading logarithmic order
are derived, including their explicit dependence on the factorization and
renormalization scales. We discuss the details pertinent to a proper numerical
implementation of the resummed results comprising an iterative solution to the
time-like evolution equations, the matching to known fixed-order expressions,
and the choice of the contour in the Mellin inverse transformation. First
extractions of parton-to-pion fragmentation functions from semi-inclusive
annihilation data are performed at different logarithmic orders of the
resummations in order to estimate their phenomenological relevance. To this
end, we compare our results to corresponding fits up to fixed,
next-to-next-to-leading order accuracy and study the residual dependence on the
factorization scale in each case.Comment: 19 pages, 7 figure
Using hadron-in-jet data in a global analysis of fragmentation functions
We present a novel global QCD analysis of charged -meson fragmentation
functions at next-to-leading order accuracy. This is achieved by making use of
the available data for single-inclusive -meson production in
electron-positron annihilation, hadron-hadron collisions, and, for the first
time, in-jet fragmentation in proton-proton scattering. It is shown how to
include all relevant processes efficiently and without approximations within
the Mellin moment technique, specifically for the in-jet fragmentation cross
section. The presented technical framework is generic and can be
straightforwardly applied to future analyses of fragmentation functions for
other hadron species, as soon as more in-jet fragmentation data become
available. We choose to work within the Zero Mass Variable Flavor Number Scheme
which is applicable for sufficiently high energies and transverse momenta. The
obtained optimum set of parton-to- fragmentation functions is
accompanied by Hessian uncertainty sets which allow one to propagate
hadronization uncertainties to other processes of interest.Comment: 16 pages, 8 figure
Threshold resummation for polarized (semi-)inclusive deep inelastic scattering
We explore the effects of the resummation of large logarithmic perturbative
corrections to double-longitudinal spin asymmetries for inclusive and
semi-inclusive deep inelastic scattering in fixed-target experiments. We find
that the asymmetries are overall rather robust with respect to the inclusion of
the resummed higher-order terms. Significant effects are observed at fairly
high values of x, where resummation tends to decrease the spin asymmetries.
This effect turns out to be more pronounced for semi-inclusive scattering. We
also investigate the potential impact of resummation on the extraction of
polarized valence quark distributions in dedicated high-x experiments.Comment: 8 pages, 6 figure