Determination of the neutron spin structure function

Anthony, P.L.; Arnold, R. G.; Band, H. R.; Borel, H.; Bosted, P.; Breton, Vincent; Cates, G. D.; Chupp, T. E.; Dietrich, F. S.; Dunne, J.; Erbacher, R.; Fellbaum, J.; Fonvieille, H.; Gearhart, R.; Holmes, R.; Hughes, E. W.; Johnson, J. R.; Kawall, D.; Keppel, C. E.; Kuhn, S. E.; Lombard-Nelsen, R. M.; Marroncle, J.; Maruyama, T.; Meyer, W.; Meziani, Z. E.; Middleton, H.; Morgenstern, J.; Newbury, Nathan R.; Petratos, G. G.; Pitthan, R.; Prepost, R.; Roblin, Y.; Rock, S. E.; Rokni, S.H.; Shapiro, G.; Smith, T. B.; Souder, P. A.; Spengos, M.; Staley, F.; Stuart, L. M.; Szalata, Z. M.; Terrien, Y.; Thompson, A. K.; White, J. L.; Woods, M.; Xu, Jun; Young, C.; Zapalac, G.

doi:10.1103/physrevlett.71.959

Cited by 470 publications

(168 citation statements)

References 36 publications

Supporting

Mentioning

157

Contrasting

Order By: Relevance

“…The blue data points are from Jlab [190], the green points are from Hermes [183], the black points are from Fermilab [78], the red points are from CERN [186] and the magenta points are from SLAC [179,181,182,184].…”

Section: Effective Chargesmentioning

confidence: 99%

See 1 more Smart Citation

The QCD running coupling

Deur

Brodsky

Téramond

2016

Progress in Particle and Nuclear Physics

298

236

View full text Add to dashboard Cite

We review the present theoretical and empirical knowledge for α s , the fundamental coupling underlying the interactions of quarks and gluons in Quantum Chromodynamics (QCD). The dependence of α s (Q 2 ) on momentum transfer Q encodes the underlying dynamics of hadron physics -from color confinement in the infrared domain to asymptotic freedom at short distances. We review constraints on α s (Q 2 ) at high Q 2 , as predicted by perturbative QCD, and its analytic behavior at small Q 2 , based on models of nonperturbative dynamics. In the introductory part of this review, we explain the phenomenological meaning of the coupling, the reason for its running, and the challenges facing a complete understanding of its analytic behavior in the infrared domain.In the second, more technical, part of the review, we discuss the behavior of α s (Q 2 ) in the high momentum transfer domain of QCD. We review how α s is defined, including its renormalization scheme dependence, the definition of its renormalization scale, the utility of effective charges, as well as "Commensurate Scale Relations" which connect the various definitions of the QCD coupling without renormalization-scale ambiguity. We also report recent significant measurements and advanced theoretical analyses which have led to precise QCD predictions at high energy. As an example of an important optimization procedure, we discuss the "Principle of Maximum Conformality", which enhances QCD's predictive power by removing the dependence of the predictions for physical observables on the choice of theoretical conventions such as the renormalization scheme. In the last part of the review, we discuss the challenge of understanding the analytic behavior α s (Q 2 ) in the low momentum transfer domain. We survey various theoretical models for the nonperturbative strongly coupled regime, such as the light-front holographic approach to QCD. This new framework predicts the form of the quark-confinement potential underlying hadron spectroscopy and dynamics, and it gives a remarkable connection between the perturbative QCD scale Λ and hadron masses. One can also identify a specific scale Q 0 which demarcates the division between perturbative and nonperturbative QCD. We also review other important methods for computing the QCD coupling, including lattice QCD, the Schwinger-Dyson equations and the GribovZwanziger analysis. After describing these approaches and enumerating their conflicting predictions, we discuss the origin of these discrepancies and how to remedy them. Our aim is not only to review the advances in this difficult area, but also to suggest what could be an optimal definition of α s (Q 2 ) in order to bring better unity to the subject.2

show abstract

Section: Effective Chargesmentioning

confidence: 99%

“…4.1 by the dashed red line. The range between the low and high Q 2 constraints is densely filled by experimental data [190], mostly coming from the Bjorken integral data [75,179,180,181,182,183,184,185,186]. Other data come from the CCFR measurement [78] of the Gross-Llewellyn Smith sum rule [74], Eq.…”

Section: Effective Chargesmentioning

confidence: 99%

The QCD running coupling

Deur

Brodsky

Téramond

2016

Progress in Particle and Nuclear Physics

298

236

View full text Add to dashboard Cite

show abstract

“…The experimental results reported in [2][3][4] suggest that the gluon spin and orbital interaction contribute significantly to the proton spin. Naturally, these experimental results require a theoretical explanation.…”

Section: Introductionmentioning

confidence: 93%

Contribution of superstring Z′ boson on the polarization effects in proton proton collisions

Muradov

Ahmadov

2005

Open Physics

View full text Add to dashboard Cite

In this work we investigate the single-and the double-spin asymmetries at the collisions of polarized protons pp → (γ * , Z 0 , Z ′ ) + X within the scope of QCD, the electroweak interaction and superstring E 6 theory. The helicity amplitude method is used. Analytical expressions for the single-and the double-spin asymmetries are obtained and their dependence on the transverse momentum of the lepton pair is investigated at the three different values of invariant masses of the lepton pair. The pure contribution coming from the superstring Z ′ boson on the single-and double-spin asymmetries has been extracted. The results obtained allow investigation of the spin structure of the proton.

show abstract

“…Using a few watts of laser light from a Tisapphire laser, an ≈50 cm 3 cell was polarized up to 40 % in tests and was maintained between 10 % and 27 % during the experiment. Double cell targets were then applied for deep inelastic scattering experiments (Johnson et al , 1995) with ≈25 GeV energy electrons at SLAC for the first studies of the neutron’s spin structure functions (Anthony et al , 1993, 1996). In this experiment, 3 He polarization between 30 % and 40 % was maintained in a 9 bar, 200 cm 3 double cell with 20 W of laser light from five Ti-sapphire lasers, each pumped with a 20W argon-ion laser (Johnson et al , 1995).…”

Section: Charged Particle and Photon Scattering Targetsmentioning

confidence: 99%

Optically polarizedHe3

et al. 2017

View full text Add to dashboard Cite

This article reviews the physics and technology of producing large quantities of highly spin-polarized 3He nuclei using spin-exchange (SEOP) and metastability-exchange (MEOP) optical pumping. Both technical developments and deeper understanding of the physical processes involved have led to substantial improvements in the capabilities of both methods. For SEOP, the use of spectrally narrowed lasers and K-Rb mixtures has substantially increased the achievable polarization and polarizing rate. For MEOP nearly lossless compression allows for rapid production of polarized 3He and operation in high magnetic fields has likewise significantly increased the pressure at which this method can be performed, and revealed new phenomena. Both methods have benefitted from development of storage methods that allow for spin-relaxation times of hundreds of hours, and specialized precision methods for polarimetry. SEOP and MEOP are now widely applied for spin-polarized targets, neutron spin filters, magnetic resonance imaging, and precision measurements.

show abstract

Determination of the neutron spin structure function

Cited by 470 publications

References 36 publications

The QCD running coupling

The QCD running coupling

Contribution of superstring Z′ boson on the polarization effects in proton proton collisions

Optically polarizedHe3

Contact Info

Product

Resources

About