12,722 research outputs found
Jet Production with Polarized Beams at Next-to-Leading Order
Jet production cross-sections in polarized proton-proton and electron-proton
collisions are studied to next-to-leading order accuracy. Phenomenological
results are presented for RHIC and HERA kinematics.Comment: 3 pages, 4 figures, talk given at the DIS99 Workshop, Zeuthen,
Germany, April 19-23, 199
Measurement of the longitudinal spin structure of the proton by COMPASS
The inclusive A_1,p and hadron double-spin asymmetries A_p^pi+, A_p^pi-,
A_p^K+, A_p^K- measured at COMPASS (CERN SPS) in deep-inelastic scattering of a
polarized muon beam off a polarized NH_3 solid target are presented. The
results have been obtained with the full statistics collected in 2007 for the
longitudinal target polarization. Proton asymmetries have been combined with
the published deuteron ones. An evaluation of the non-singlet spin-dependent
structure function g_1^NS(x,Q^2) and its first moment, which confirms the
validity of the Bjorken sum-rule, is presented. A LO evaluation of polarized
quark densities is also presented. The use of the proton data allows to perform
a full flavor separation and to extract individual helicity densities of u, d,
anti-u, anti-d and s quarks. All sea quark densities are found to be compatible
with zero in the full range of the measurements.Comment: 4 pages, 5 figures, presented at the 3rd joint International HADRON
STRUCTURE '09 Conference, Tatranska Strba (Slovak Republic
Polarized Fragmentation Functions
In this talk I present a review on the theoretical status of polarized
fragmentation functions and the prospects for conceivable future semi-inclusive
deep-inelastic scattering and proton-proton collision experiments to measure
them.Comment: Talk at the Electron Polarized Ion Collider Workshop (EPIC99), at
IUCF, Bloomington, IA, April 1999, 15 pp, 6 fig
Transversely polarized Drell-Yan asymmetry AT T at NLO
We present the first fully differential next-To-leading order QCD calculation for lepton production in transversely polarized hadronic collisions, pâpââ±X, where the lepton arises from the decay of an electroweak gauge boson. The calculation is implemented in the Monte-Carlo like code che that already includes the unpolarized and longitudinally polarized cross sections and may be readily used to perform a comparison to experimental data and to extract information on the related parton distributions. We analyze the perturbative stability of the cross-section and double spin asymmetry ATT at RHIC kinematics. We find that the QCD corrections are non-negligible even at the level of asymmetries and that they strongly depend on the lepton kinematics. Furthermore, we present two scenarios for transversely polarized parton distributions, based on the de Florian-Sassot-Stratmann-Vogelsang (DSSV) set of longitudinally parton densities and fully evolved to NLO accuracy, that can be used for the evaluation of different observables involving transverse polarization.Fil: de Florian, Daniel Enrique. Universidad Nacional de San MartĂn. Escuela de Ciencia y TecnologĂa. Centro Internacional de Estudios Avanzados; Argentina. TĂŒbingen University; Alemania. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentin
Next to leading order evolution of SIDIS processes in the forward region
We compute the order quark initiated corrections to
semi-inclusive deep inelastic scattering extending the approach developed
recently for the gluon contributions. With these corrections we complete the
order QCD description of these processes, verifying explicitly the
factorization of collinear singularities. We also obtain the corresponding NLO
evolution kernels, relevant for the scale dependence of fracture functions. We
compare the non-homogeneous evolution effects driven by these kernels with
those obtained at leading order accuracy and discuss their phenomenological
implications.Comment: 18 pages, 4 ps figures, uses revtex4 and feynmf. Accepted for
publication in Nuclear Physics
Polarized semi-inclusive electroweak structure functions at next-to-leading-order
We present a next-to-leading order (NLO) computation of the full set of
polarized and unpolarized electroweak semi-inclusive DIS (SIDIS) structure
functions, whose knowledge is crucial for a precise extraction of polarized
parton distributions. We focus on the phenomenology of the polarized structure
functions for the kinematical conditions that could be reached in an
Electron-Ion-Collider.
We show that the NLO corrections are sizeable, particularly in the small-
range. We test the sensitivity of these structure functions on certain quark
distributions and compare it to the situation of inclusive DIS and
electromagnetic SIDIS.Comment: 17 pages, 5 figure
Order-alpha_s^2 corrections to one-particle inclusive processes in DIS
We analyze the order- QCD corrections to semi-inclusive deep
inelastic scattering and present results for processes initiated by a gluon. We
focus in the most singular pieces of these corrections in order to obtain the
hitherto unknown NLO evolution kernels relevant for the non homogeneous QCD
scale dependence of these cross sections, and to check explicitly factorization
at this order. In so doing we discuss the prescription of overlapping
singularities in more than one variable.Comment: 16 pages, 9 eps figures. Uses revtex4 and feynm
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
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