Azimuthal and single spin asymmetries in hard scattering processes

D’Alesio, U.; Murgia, F.

doi:10.1016/j.ppnp.2008.01.001

Cited by 181 publications

(101 citation statements)

References 276 publications

(529 reference statements)

Supporting

Mentioning

100

Contrasting

Order By: Relevance

“…Indeed, in the Drell-Yan process, even when both the beam and target are unpolarized, the annihilating quark and antiquark have a transversemomentum-dependent transversity. Extensive discussions of distributions associated with quark spin asymmetries are presented in (Barone et al, 2002;D'Alesio and Murgia, 2008).…”

Section: F Azimuthal Asymmetriesmentioning

confidence: 99%

Nucleon and pion distribution functions in the valence region

2010

View full text Add to dashboard Cite

We provide an experimental and theoretical perspective on the behavior of unpolarized distribution functions for the nucleon and pion on the valence-quark domain; namely, Bjorken-x > ∼ 0.4. This domain is key to much of hadron physics; e.g., a hadron is defined by its flavor content and that is a valence-quark property. Furthermore, its accurate parametrization is crucial to the provision of reliable input for large collider experiments. We focus on experimental extractions of distribution functions via electron and muon inelastic scattering, and from Drell-Yan interactions; and on theoretical treatments that emphasize an explanation of the distribution functions, providing an overview of major contemporary approaches and issues. Valence-quark physics is a compelling subject, which probes at the heart of our understanding of the Standard Model. There are numerous outstanding and unresolved challenges, which experiment and theory must confront. In connection with experiment, we explain that an upgraded Jefferson Lab facility is well-suited to provide new data on the nucleon, while a future electron ion collider could provide essential new data for the mesons. There is also great potential in using Drell-Yan interactions, at FNAL, J-PARC and GSI, to push into the large-x domain for both mesons and nucleons. We argue furthermore that explanation, in contrast to modeling and parametrization, requires a widespread acceptance of the need to adapt theory: to the lessons learnt already from the methods of nonperturbative quantum field theory; and a fuller exploitation of those methods. * Electronic address: holt@anl.gov † Electronic address: cdroberts@anl.gov

show abstract

Section: F Azimuthal Asymmetriesmentioning

confidence: 99%

Nucleon and pion distribution functions in the valence region

2010

View full text Add to dashboard Cite

show abstract

“…However, substantial asymmetries have been observed in a wide range of center-of-mass energiesunexpected from a pQCD point of view-and still today they are subject to intense investigations (for a review on this subject see, e.g., Ref. [18]). This stimulated interest in looking at inclusive electroproduction of hadrons, i.e., ep → hX where only one hadron of the final state is tagged.…”

Section: Pos(lc2010)052mentioning

confidence: 99%

Recent developments at HERMES

Schnell¹

2010

Proceedings of Light Cone 2010: Relativistic Hadronic and Particle Physics — PoS(LC2010)

View full text Add to dashboard Cite

Azimuthal single-spin asymmetries in inclusive and semi-inclusive electro-production of pions and charged kaons were measured on a transversely polarized hydrogen target. Evidence for a naive-T-odd, transverse-momentum-dependent parton distribution function is deduced from nonvanishing Sivers effects for π + , π 0 , and K ± , as well as in the difference of the π + and π − cross sections. Further azimuthal modulations of the semi-inclusive single-spin asymmetry were found to be consistent with zero except the one related to the Collins effect and one that is subleading in an expansion of the cross section in 1/Q. The single-spin asymmetries in inclusive electro-production of charged pions and kaons were found to be non-zero except for K − , and to qualitatively resemble the pattern of the Sivers amplitudes.

show abstract

“…Far from being a complete summary, this table gives however an idea of the present phenomenological activity in the field (see also Refs. [2,3]). …”

Section: Phenomenologymentioning

confidence: 99%