Sivers and Collins single spin asymmetries

Efremov, A.V.; Goeke, K.; Schweitzer, P.

doi:10.1140/epjst/e2008-00768-9

Cited by 13 publications

(14 citation statements)

References 61 publications

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“…The beam SSA, first measured by CLAS collaboration [18] (see Fig. 2, right panel) have also been interpreted in terms of the Collins mechanism [36][37][38][39] and used for a first determination of the twist-3 distribution function e(x) [37]. The magnitude of the extracted e(x) is also consistent with predictions using the chiral quark soliton model [40][41][42].…”

Section: Spin-azimuthal Asymmetriessupporting

confidence: 59%

Structure and spin of the nucleon

Avakian

2014

EPJ Web of Conferences

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Abstract.Parton distribution functions, describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been recently generalized to account also for transverse degrees of freedom. Two new sets of more general distributions, Transverse Momentum Distributions and Generalized Parton Distributions, were introduced to describe transverse momentum and space distributions of partons. Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs) in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL). TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC), FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.

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Section: Spin-azimuthal Asymmetriessupporting

confidence: 59%

Structure and spin of the nucleon

Avakian

2014

EPJ Web of Conferences

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“…Having in mind the phenomenology that could be explored at GSI-FAIR and CERN, or at J-PARC and RHIC, we limit the physics case to the most relevant combinations. The master channel is thē [25][26][27], whose polarized q T −integrated cross section is simply [44] …”

Section: B Drell-yanmentioning

confidence: 99%

“…At FAIR (GSI), the PAX collaboration is planning to measure the fully polarized DrellYan process with antiprotons in order to perform a self-consistent extraction of the transversity distribution [25][26][27][28][29]. Moreover, by simply switching on and off the transverse polarization of only one hadron, from the combination of the various cross sections it is possible to extract h 1 also together with the Boer-Mulders function h …”

Section: B the Ssa In Sidismentioning

confidence: 99%

“…For example, at JLab the E06-010 experiment [24] is measuring the Collins and the Sivers effects using the 6 GeV energy beam hitting on a transversely polarized 3 He (effective neutron) target, in order to extract the neutron transversity distribution. As for Drell-Yan, the fully polarized process with antiprotons is planned to be measured at FAIR (GSI), in order to perform a self-consistent extraction of the transversity distribution [25][26][27][28][29]; while the COMPASS collaboration is planning to measure a SSA using a high energetic pion beam on a transversely polarized proton target at CERN [30][31][32][33], where the T-odd Sivers function could be extracted and its predicted non-universal behaviour directly tested [34].…”

Section: Introductionmentioning

confidence: 99%

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Weighted azimuthal asymmetries in a diquark spectator model

et al. 2010

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We analytically calculate weighted azimuthal asymmetries in semi-inclusive lepton-nucleon deepinelastic scattering and Drell-Yan processes, using transverse-momentum-dependent partonic densities obtained in a diquark spectator model. We compare the asymmetries with available preliminary experimental data, in particular for the Collins and the Sivers effect. We make predictions for other cases of interest in running and planned experiments.

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“…The COMPASS data are still today the only SIDIS data ever taken on a transversely polarised deuteron target and provide constraints on the d-quark contribution 1 . Together with the HERMES and Belle data they allowed for the first global analyses and first extractions [14,15] of the transversity distributions for u-and d-quarks and of favoured and unfavoured Collins FFs. It is important to note that global analyses of e + e − → hadrons and SIDIS data are a necessity, since neither can the Collins FF be extracted from e + e − data alone, nor can the Collins and transversity functions be disentangled using only SIDIS data.…”

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confidence: 99%

I – Experimental investigation of transverse spin asymmetries in μ-p SIDIS processes: Collins asymmetries

Adolph¹,

Alekseev²,

Alexakhin³

et al. 2012

Physics Letters B

119

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The COMPASS Collaboration at CERN has measured the transverse spin azimuthal asymmetry of charged hadrons produced in semi-inclusive deep inelastic scattering using a 160 GeV µ + beam and a transversely polarised NH 3 target. The Collins asymmetry of the proton was extracted in the Bjorken x range 0.003 < x < 0.7. These new measurements confirm with higher accuracy previous measurements from the COMPASS and HERMES collaborations, which exhibit a definite effect in the valence quark region. The asymmetries for negative and positive hadrons are similar in magnitude and opposite in sign. They are compatible with model calculations in which the u-quark transversity is opposite in sign and somewhat larger than the d-quark transversity distribution function. The asymmetry is extracted as a function of Bjorken x, the relative hadron energy z and the hadron transverse momentum p h T . The high statistics and quality of the data also allow for more detailed investigations of the dependence on the kinematic variables. These studies confirm the leading-twist nature of the Collins asymmetry.

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Sivers and Collins single spin asymmetries

Abstract: The Sivers and Collins asymmetries are the most prominent Single Spin Asymmetries (SSA) in Semi-Inclusive Deeply Inelastic Scattering (SIDIS) with transverse target polarization. In this talk we present our understanding of these phenomena.

Cited by 13 publications

References 61 publications

Structure and spin of the nucleon

Structure and spin of the nucleon

Weighted azimuthal asymmetries in a diquark spectator model

I – Experimental investigation of transverse spin asymmetries in μ-p SIDIS processes: Collins asymmetries

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