Impact of hadronic and nuclear corrections on global analysis of spin-dependent parton distributions

Jimenez-Delgado, Pedro; Accardi, Alberto; Melnitchouk, Wally

doi:10.1103/physrevd.89.034025

Cited by 70 publications

(111 citation statements)

References 112 publications

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“…Our results for A 1 + ηA 2 have the least theoretical bias from unmeasured structure functions like A 2 and F 1 , and are therefore the preferred choice for NLO fits that will include our data in the high-Q 2 , high-W region, like the fit by the JAM collaboration [80]. They can be found in the CLAS database [81] and in the Supplemental Material [82] for this paper.…”

Section: A Results For A1 + ηA2mentioning

confidence: 99%

Precise determination of the deuteron spin structure at low to moderateQ2with CLAS and extraction of the neutron contribution

Guler¹,

Fersch²,

Kuhn³

et al. 2015

Phys. Rev. C

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Precise determination of the deuteron spin structure at low to moderate Q^{2} with CLAS and extraction of the neutron contribution We present the final results for the deuteron spin structure functions obtained from the full data set collected with Jefferson Lab's CLAS in 2000-2001. Polarized electrons with energies of 1.6, 2.5, 4.2 and 5.8 GeV were scattered from deuteron ( 15 ND3) targets, dynamically polarized along the beam direction, and detected with CLAS. From the measured double spin asymmetry, the virtual photon absorption asymmetry A d 1 and the polarized structure function g d 1 were extracted over a wide kinematic range (0.05 GeV 2 < Q 2 < 5 GeV 2 and 0.9 GeV < W < 3 GeV). We use an unfolding procedure and a parametrization of the corresponding proton results to extract from these data the polarized structure functions A n 1 and g n 1 of the (bound) neutron, which are so far unknown in the resonance region, W < 2 GeV. We compare our final results, including several moments of the deuteron and neutron spin structure functions, with various theoretical models and expectations as well as parametrizations of the world data. The unprecedented precision and dense kinematic coverage of these data can aid in future extractions of polarized parton distributions, tests of perturbative QCD predictions for the quark polarization at large x, a better understanding of quark-hadron duality, and more precise values for higher-twist matrix elements in the framework of the Operator Product Expansion.

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Section: A Results For A1 + ηA2mentioning

confidence: 99%

Precise determination of the deuteron spin structure at low to moderateQ2with CLAS and extraction of the neutron contribution

Guler¹,

Fersch²,

Kuhn³

et al. 2015

Phys. Rev. C

View full text Add to dashboard Cite

show abstract

“…Data from several experiments are expected to be collected for values of x as high as ≈ 0.8 for DIS kinematics, and even higher x in the nucleon resonance region. This should significantly reduce the PDF uncertainties for x 0.5, especially for the ∆ d + distribution, which will be more strongly constrained by new data on the 3 He asymmetry.…”

Section: Polarized Case: Jammentioning

confidence: 99%

“…We include data from all polarized DIS experiments that lie within the limits Q 2 ≥ 1 GeV 2 and W 2 ≥ 3.5 GeV 2 , which allows us to constrain the ∆ u + and ∆ d + distributions 1 up to x ≈ 0.7. Obtaining stable fits over this expanded kinematic range necessitates systematically accounting for target mass and higher twist corrections, which are vital for describing the g 1 and g 2 structure functions at the lower Q 2 range, and nuclear smearing corrections for deuterium and 3 He nuclei, which have major impact at large x. The results of the JAM13 fits indicate that the ∆ d + distribution has a significantly larger magnitude in the intermediate-x region (x 0.2) than in previous analyses, due primarily to the sizable higher twist corrections found here and shown in Fig.…”

Section: Polarized Case: Jammentioning

confidence: 99%

“…The first global NLO analysis of spin-dependent PDFs from the JAM collaboration [3] utilizes the available data on inclusive polarized DIS from protons, deuterons and 3 He. Where possible, we have fitted directly the measured polarization asymmetries, rather than relying on structure functions extracted under different conditions than the unpolarized cross sections.…”

Section: Polarized Case: Jammentioning

confidence: 99%

“…2 by discussing some aspects of the recent JR14 analysis [2]. Section 3 will be devoted to the polarized case and will report on the first extraction by the Jefferson Lab Angular Momentum Collaboration, JAM13 [3], as well as on later results on constraints at large momentum fractions by future data from Jefferson Lab at 12 GeV [4].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Delineating the Polarized and Unpolarized Partonic Structure of the Nucleon

Jimenez-Delgado

2015

Few-Body Syst

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Reports on our latest extractions of parton distribution functions of the nucleon are given. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are reported, including a careful treatment of hadronic and nuclear corrections, as well as reports on the impact of present and future data in our understanding of the spin of the nucleon.

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Orbital angular momentum at small x revisited

Kovchegov,

Manley

2024

J. High Energ. Phys.

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We revisit the problem of the small Bjorken-x asymptotics of the quark and gluon orbital angular momentum (OAM) distributions in the proton utilizing the revised small-x helicity evolution derived recently in [1]. We relate the quark and gluon OAM distributions at small x to the polarized dipole amplitudes and their (first) impact-parameter moments. To obtain the OAM distributions, we derive novel small-x evolution equations for the impact-parameter moments of the polarized dipole amplitudes in the double-logarithmic approximation (summing powers of αs ln2(1/x) with αs the strong coupling constant). We solve these evolution equations numerically and extract the leading large-Nc, small-x asymptotics of the quark and gluon OAM distributions, which we determine to be$$ {L}_{q+\overline{q}}\left(x,{Q}^2\right)\sim {L}_G\left(x,{Q}^2\right)\sim \Delta \Sigma \left(x,{Q}^2\right)\sim \Delta G\left(x,{Q}^2\right)\sim {\left(\frac{1}{2}\right)}^{3.66\sqrt{\frac{\alpha_s{N}_c}{2\uppi}}}, $$ L q + q ¯ x Q 2 ~ L G x Q 2 ~ ∆ Σ x Q 2 ~ ∆ G x Q 2 ~ 1 2 3.66 α s N c 2 π , in agreement with [2] within the precision of our numerical evaluation. (Here Nc is the number of quark colors.) We also investigate the ratios of the quark and gluon OAM distributions to their helicity distribution counterparts in the small-x region.

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Impact of hadronic and nuclear corrections on global analysis of spin-dependent parton distributions

Cited by 70 publications

References 112 publications

Precise determination of the deuteron spin structure at low to moderateQ2with CLAS and extraction of the neutron contribution

Precise determination of the deuteron spin structure at low to moderateQ2with CLAS and extraction of the neutron contribution

Delineating the Polarized and Unpolarized Partonic Structure of the Nucleon

Orbital angular momentum at small x revisited

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