The Spin Structure of the Nucleon

Aidala, Christine A.; Bass, Steven D.; Hasch, Delia; Mallot, Gerhard K.

doi:10.48550/arxiv.1209.2803

Cited by 30 publications

(37 citation statements)

References 199 publications

(258 reference statements)

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“…Since the experimental discovery that the quark spin only contributes a small portion to the nucleon spin [1], the nucleon spin problem has attracted tremendous experimental and theoretical efforts over the past around two decades [2]. Nevertheless, how to formulate complete and gauge invariant decompositions of the nucleon spin and particularly how to formulate gauge invariant descriptions of the gluon polarization remains an open and interesting theoretical problem so far.…”

Section: Introductionmentioning

confidence: 99%

Gauge invariant descriptions of gluon polarizations

Guo¹,

Schmidt²

2013

Phys. Rev. D

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We propose methods to construct gauge invariant decompositions of the nucleon spin, particularly gauge invariant descriptions of the gluon polarization. We show that gauge invariant decompositions of the nucleon spin can be derived naturally from the conserved current of a generalized Lorentz transformation by the Noether theorem. We propose a gauge invariant extension of the Chern-Simons current as a possible description of the gluon spin, and we also examine the problem of gauge dependence of this extended Chern-Simons current.

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Section: Introductionmentioning

confidence: 99%

Gauge invariant descriptions of gluon polarizations

Guo¹,

Schmidt²

2013

Phys. Rev. D

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“…There have been decades of careful experimental investigation since the original discovery of the so-called proton spin crisis by the European Muon Collaboration (EMC) [1][2][3][4]. The fraction of the spin of the proton carried by its quarks currently stands at [5] 33 ± 3 ± 5 %, if one relies on SU(3) symmetry for the octet axial charge, g 8 A .…”

mentioning

confidence: 99%

Octet Spin Fractions and the Proton Spin Problem

et al. 2013

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The relatively small fraction of the spin of the proton carried by its quarks presents a major challenge to our understanding of the strong interaction. Traditional efforts to explore this problem have involved new and imaginative experiments and QCD based studies of the nucleon. We propose a new approach to the problem which exploits recent advances in lattice QCD. In particular, we extract values for the spin carried by the quarks in other members of the baryon octet in order to see whether the suppression observed for the proton is a general property or depends significantly on the baryon structure. We compare these results with the values for the spin fractions calculated within a model that includes the effects of confinement, relativity, gluon exchange currents and the meson cloud required by chiral symmetry, finding a very satisfactory level of agreement given the precision currently attainable.

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“…where F AB,C are the spin-dependent structure functions, with A, B, and C indicating the polarization of the polarized incoming proton, the unpolarized incoming proton or lepton, and the outgoing hadron inside the jet, respectively. Note that the situation where both incoming protons (or proton-lepton) are polarized have been extensively studied in the literature [64], and can be used to explore the polarized PDFs. Our focus here is to understand how the polarization in the fragmentation functions inside the jet can couple with the polarization in the incoming proton and thus to figure out the novel insights that come with these observables.…”

Section: General Structure Of the Observablesmentioning

confidence: 99%

Polarized jet fragmentation functions

Kang,

Lee,

Zhao

2020

Preprint

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We develop the theoretical framework needed to study the distribution of hadrons with general polarization inside jets, with and without transverse momentum measured with respect to the standard jet axis. The key development in this paper, referred to as "polarized jet fragmentation functions", opens up new opportunities to study both collinear and transverse momentum dependent (TMD) fragmentation functions. As two examples of the developed framework, we study longitudinally polarized collinear Λ and transversely polarized TMD Λ production inside jets in both pp and ep collisions. We find that both observables have high potential in constraining spin-dependent fragmentation functions with sizeable asymmetries predicted, in particular, at the future Electron-Ion Collider.

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The Spin Structure of the Nucleon

Cited by 30 publications

References 199 publications

Gauge invariant descriptions of gluon polarizations

Gauge invariant descriptions of gluon polarizations

Octet Spin Fractions and the Proton Spin Problem

Polarized jet fragmentation functions

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