Polarized parton distributions in the nucleon

Gehrmann, Thomas; Stirling, W.J.

doi:10.1103/physrevd.53.6100

Cited by 312 publications

(578 citation statements)

References 60 publications

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“…Our results obtained from this analysis refer to the Adler{Bardeen (AB) factorization scheme. They are similar to results recently obtained by other groups [26,27]. The structure functions g 1 of the proton and the deuteron are decomposed into a polarized singlet quark distribution (x) and nonsinglet quark distributions q p NS (x) and q d NS (x).…”

supporting

confidence: 65%

The spin-dependent structure function g1(x) of the deuteron from polarized deep-inelastic muon scattering

Adams¹,

Adeva²,

Akdoğan³

et al. 1997

Physics Letters B

100

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supporting

confidence: 65%

The spin-dependent structure function g1(x) of the deuteron from polarized deep-inelastic muon scattering

Adams¹,

Adeva²,

Akdoğan³

et al. 1997

Physics Letters B

100

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“…To study this question, we use three different models or fits to the polarized quark distributions. These are the fits of Gehrmann and Stirling (GS) [7], of Glück, Reya, Stratmann, and Vogelsang (GRSV) [8], and a suggestion of Soffer et al [9]. All fit the available data on g 1 from deep inelastic lepton scattering experiments.…”

Section: Resultsmentioning

confidence: 99%

Probing polarized parton distributions with meson photoproduction

1997

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Polarization asymmetries in photoproduction of high transverse momentum mesons are a flavor sensitive way to measure the polarized quark distributions. We calculate the expected asymmetries in several models, and find that the asymmetries are significant and also significantly different from model to model. Suitable data may come as a by-product of deep inelastic experiments to measure g1 or from dedicated experiments. JLAB-THY-96-18 I. MOTIVATIONIn this note, we will describe a flavor sensitive tool for measuring polarized quark distributions, namely photoproduction off nucleons of mesons with high transverse momentum, using polarized initial states.Presently, information on polarized quark distributions comes from deep inelastic electron or muon scattering with polarized beams and targets [1]. Single arm measurements of g 1 give information about a linear combination of polarized quark distributions. Obtaining polarized distributions of individual flavors from this data requires extra theoretical input in the analysis. Recently, coincidence measurements of ℓ p( d) → ℓ π ± X have been reported [2]. This data, for a proton or deuteron target, gives different linear combinations of up and down quark polarized distributions, allowing a flavor decomposition without further theoretical input [3].The process we will discuss, γ p → M X (where the photon is real, targets other than protons are possible, and M is a meson), gives a complementary way to find the polarized quark distributions. The perturbative QCD that we use in the analysis is justified on the basis of high meson transverse momentum, rather than by high virtuality of an exchanged photon, and the experiment is a single arm experiment rather than a coincidence one. Good data can in fact come as a by-product of a g 1 experiment since the detectors that measure the final electron or muon can also pick up charged hadrons; recall that if the final lepton is not measured, the form of the cross section ensures that the virtuality of the exchanged photon will be rather low on the average.At high enough transverse momentum, mesons are directly produced by short range processes illustrated in Fig. 1. These processes are amenable to perturbative QCD calculation [4,5] and produce mesons that are kine- * On leave from Kharkov Institute of Physics and Technology, Kharkov, Ukraine.matically isolated in the direction they emerge. The direct processes possess several important features. One important feature is that the momentum fraction of the active quark is immediately obtainable from experimentally measurable quantities. This is like the situation in deep inelastic lepton scattering, where experimenters can measure Q 2 and ν and determine the quark momentum fraction by x = Q 2 /2m N ν. In the present case, we define the Mandelstam variables using p, q, and k, the momenta of the proton (or other target hadron), the photon, and the meson, respectively,These are all experimentally measurable quantities. We can show that, neglecting masses,The second important feature is t...

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“…They parametrise the probability of finding partons inside the nucleon having their spin aligned or anti-aligned to the nucleon spin and are obtained from a global fit [7][8][9][10][11][12] to spin asymmetries in polarized lepton-hadron and hadron-hadron collisions. They can be used to predict cross sections in collisions of hadrons with fixed spin orientation.…”

Section: Introductionmentioning

confidence: 99%

Spin asymmetries in squark and gluino production at polarized hadron colliders

2004

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We study the production cross sections for squarks and gluinos in collision of longitudinally polarized hadrons. The corresponding polarized partonic cross sections are computed in leading order supersymmetric QCD. The resulting asymmetries are evaluated for the polarized proton collider RHIC, as well as for hypothetical polarized options of the Tevatron and the LHC. These asymmetries turn out to be sizable over a wide range of supersymmetric particle masses. Once supersymmetric particles are discovered in unpolarized collisions, a measurement of the spin asymmetries would thus potentially help to establish the properties of the newly discovered particles and open a window to detailed sparticle spectroscopy at future polarized hadron colliders.

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Polarized parton distributions in the nucleon

Cited by 312 publications

References 60 publications

The spin-dependent structure function g1(x) of the deuteron from polarized deep-inelastic muon scattering

The spin-dependent structure function g1(x) of the deuteron from polarized deep-inelastic muon scattering

Probing polarized parton distributions with meson photoproduction

Spin asymmetries in squark and gluino production at polarized hadron colliders

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