51 research outputs found
Extracting the Strange Density from
We present a QCD analysis of the strange and charm contributions to the
neutrino deep inelastic structure function . We show that next-to-leading
order effects, which are relatively important for , play a lesser role in
the case of . The neutrino--antineutrino difference provides a new determination of the strange density, which
exhibits some advantages with respect to other traditional methods.Comment: 12 page
Comparing extractions of Sivers functions
A comparison is given of the various recently published extractions of the
Sivers functions from the HERMES and COMPASS data on single-transverse spin
asymmetries in semi-inclusive deeply inelastic scattering.Comment: Contribution to the proceedings of "The International Workshop on
Transverse Polarisation Phenomena in Hard Processes" (Transversity 2005),
Villa Olmo (Como), 7-10th. September 200
Extraction of TMDs with global fits
We present a brief review of our recent extractions of the Transverse-Momentum–Dependent distribution and fragmentation functions performed by analysing
Semi-Inclusive Deep Inelastic Scattering and e+e− → h1h2 + X data on azimuthal asymmetries
The LHCSpin Project
LHCSpin aims at installing a polarized gas target in front of the LHCb
spectrometer, bringing, for the first time, polarized physics to the LHC. The
project will benefit from the experience achieved with the installation of an
unpolarized gas target at LHCb during the LHC Long Shutdown 2. LHCb will then
become the first experiment simultaneously running in collider and fixed-target
mode with polarized targets, opening a whole new range of explorations to its
exceptional spectrometer.
LHCSpin will offer a unique opportunity to probe polarized quark and gluon
parton distributions in nucleons and nuclei, especially at high and
intermediate , where experimental data are still largely missing. Beside
standard collinear parton distribution functions (PDFs), LHCSpin will make it
possible to study multidimensional polarized parton distributions that depend
also on parton transverse momentum.
The study of the multidimensional partonic structure of the nucleon,
particularly including polarization effects, can test our knowledge of QCD at
an unprecedented level of sophistication, both in the perturbative and
nonperturbative regime. At the same time, an accurate knowledge of hadron
structure is necessary for precision measurements of Standard Model (SM)
observables and discovery of physics beyond the SM.
Due to the intricate nature of the strong interaction, it is indispensable to
perform the widest possible suite of experimental measurements. It will be
ideal to have two new projects complementing each other: a new facility for
polarized electron-proton collisions and a new facility for polarized
proton-proton collisions. LHCSpin stands out at the moment as the most
promising candidate for the second type of project, going beyond the kinematic
coverage and the accuracy of the existent experiments, especially on the
heavy-quark sector
Photoproduction of mesons associated with a leading neutron
The photoproduction of mesons associated with a leading
neutron has been observed with the ZEUS detector in collisions at HERA
using an integrated luminosity of 80 pb. The neutron carries a large
fraction, {}, of the incoming proton beam energy and is detected at
very small production angles, { mrad}, an indication of
peripheral scattering. The meson is centrally produced with
pseudorapidity {
GeV}, which is large compared to the average transverse momentum of the neutron
of 0.22 GeV. The ratio of neutron-tagged to inclusive production is
in the photon-proton
center-of-mass energy range { GeV}. The data suggest that the
presence of a hard scale enhances the fraction of events with a leading neutron
in the final state.Comment: 28 pages, 4 figures, 2 table
Measurement of dijet photoproduction for events with a leading neutron at HERA
Differential cross sections for dijet photoproduction and this process in
association with a leading neutron, e+ + p -> e+ + jet + jet + X (+ n), have
been measured with the ZEUS detector at HERA using an integrated luminosity of
40 pb-1. The fraction of dijet events with a leading neutron was studied as a
function of different jet and event variables. Single- and double-differential
cross sections are presented as a function of the longitudinal fraction of the
proton momentum carried by the leading neutron, xL, and of its transverse
momentum squared, pT^2. The dijet data are compared to inclusive DIS and
photoproduction results; they are all consistent with a simple pion-exchange
model. The neutron yield as a function of xL was found to depend only on the
fraction of the proton beam energy going into the forward region, independent
of the hard process. No firm conclusion can be drawn on the presence of
rescattering effects.Comment: 40 pages, 18 figure
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