1,721,045 research outputs found
Partonic transverse motion in unpolarized semi-inclusive deep inelastic scattering processes
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Extraction of the Sivers functions with TMD evolution
No full textThe QCD evolution of the unpolarized Transverse Momentum Dependent (TMD) distribution and fragmentation functions and of the Sivers function have been discussed in recent papers [1, 2, 3, 4]. Following these results we reconsider previous extractions of the Sivers function from SIDIS data and propose a simple strategy which allows to take into account the Q2 dependence of the TMDs. Clear evidence of the TMD evolution can be seen in the available data, mostly in the newest COMPASS results for Semi Inclusive Deep Inelastic Scattering (SIDIS) off a transversely polarized proton target
A general formalism for single and double spin asymmetries in inclusive hadron production
No full textPartonic Transverse Motion in Unpolarized Semi-Inclusive Deep Inelastic Scattering Processes
No full textA strategy towards the extraction of the Sivers function with TMD evolution
Full text linkThe QCD evolution of the unpolarized transverse momentum dependent (TMD) distribution functions and of the Sivers functions have been discussed in recent papers. Following such results we reconsider previous extractions of the Sivers functions from semi-inclusive deep inelastic scattering data and propose a simple strategy which allows to take into account the Q2 dependence of the TMDs in comparison with experimental findings. A clear evidence of the phenomenological success of the TMD-evolution equations is given, mostly, by the newest COMPASS data off a transversely polarized proton targe
Phenomenology of Sivers Effect with TMD Evolution
No full textFollowing the TMD evolution scheme recently proposed for the unpolarized and the Sivers distribution function, we propose a simple strategy to take into account this TMD Q2 dependence in our phenomenological extraction of the Sivers function from SIDIS data. New results are presented and possible future applications are discussed
Non-perturbative QCD effects in qT spectra of Drell-Yan and Z-boson production
No full textThe factorization theorems for transverse momentum distributions of dilepton/boson production, recently formulated by Collins and Echevarria-Idilbi-Scimemi in terms of well-defined transverse momentum dependent distributions (TMDs), allows for a systematic and quantitative analysis of non-perturbative QCD effects of the cross sections involving these quantities. In this paper we perform a global fit using all current available data for Drell-Yan and Z-boson production at hadron colliders within this framework. The perturbative calculable pieces of our estimates are included using a complete resummation at next-to-next-to-leading-logarithmic accuracy. Performing the matching of transverse momentum distributions onto the standard collinear parton distribution functions and recalling that the corresponding matching coefficient can be partially exponentiated, we find that this exponentiated part is spin-independent and resummable. We argue that the inclusion of higher order perturbative pieces is necessary when data from lower energy scales are analyzed. We consider non-perturbative corrections both to the intrinsic nucleon structure and to the evolution kernel and find that the non-perturbative part of the TMDs could be parametrized in terms of a minimal set of parameters (namely 2-3). When all corrections are included the global fit so performed gives a χ2 /d.o.f. ≲ 1 and a very precise prediction for vector boson production at the Large Hadron Collider (LHC)
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