Quark helicity distributions from longitudinal spin asymmetries in muon–proton and muon–deuteron scattering

Windmolders, R.

doi:10.1016/j.physletb.2010.08.034

Cited by 135 publications

(91 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We note that small strange-quark charges have also been observed in recent studies [15,16]. Within the present uncertainty, our results for the axial charges, g A and g s A , are consistent with the experimental values [17,18]. The suppression compared to the simple quark model estimate, g s A = 1 and g A = 5/3, was argued by one of the authors in Schwinger-Dyson analyses [19,20].…”

Section: Pos(lattice 2015)121supporting

confidence: 93%

Nucleon axial and tensor charges with dynamical overlap quarks

Yamanaka¹,

Ohki²,

Hashimoto³

et al. 2016

Proceedings of the 33rd International Symposium on Lattice Field Theory — PoS(LATTICE 2015)

View full text Add to dashboard Cite

We report on our calculation of the nucleon axial and tensor charges in 2+1-flavor QCD with dynamical overlap quarks. Gauge ensembles are generated at a single lattice spacing 0.12 fm and at a strange quark mass close to its physical value. We employ the all-mode-averaging technique to calculate the relevant nucleon correlation functions, and the disconnected quark loop is efficiently calculated by using the all-to-all quark propagator. We present our preliminary results for the isoscalar and isovector charges obtained at pion masses m π = 450 and 540 MeV.

show abstract

Section: Pos(lattice 2015)121supporting

confidence: 93%

Nucleon axial and tensor charges with dynamical overlap quarks

Yamanaka¹,

Ohki²,

Hashimoto³

et al. 2016

Proceedings of the 33rd International Symposium on Lattice Field Theory — PoS(LATTICE 2015)

View full text Add to dashboard Cite

show abstract

“…In this case, there will be no strangeness contribution, Ás to ÁAE ¼ Áu þ Ád þ Ás þÁÁÁ, where, in our notation, Áq ¼ ÁAE q contains both the spin of the quarks q and of the antiquarks " q. Experimentally, Ás is obtained by integrating the strangeness contribution ÁsðxÞ to the spin structure function g 1 over the momentum fraction x. The integral over the range in which data exist agrees with zero; see, e.g., new COMPASS data [2,3] for x ! 0:004 or HERMES data [4] for x !…”

mentioning

confidence: 88%

Strangeness Contribution to the Proton Spin from Lattice QCD

et al. 2012

View full text Add to dashboard Cite

We compute the strangeness and light-quark contributions Delta s, Delta u and Delta d to the proton spin in nf=2 lattice QCD at a pion mass of about 285 MeV and at a lattice spacing a approx 0.073 fm, using the non-perturbatively improved Sheikholeslami-Wohlert Wilson action. We carry out the renormalization of these matrix elements which involves mixing between contributions from different quark flavours. Our main result is the small negative value MSbar scheme value Delta s = -0.020(10)(4), at a scale mu = 7.4 GeV, of the strangeness contribution to the nucleon spin. The second error is an estimate of the uncertainty, due to the missing extrapolation to the physical point.Comment: 5 pages, 2 figures, V2: minor changes, to enhance the readability of the article. References updated. "The" removed from the titl

show abstract

“…This fact has surprised many physicists, and many theoretical studies trying to explain this "proton spin crisis" have been done [15,[17][18][19][20] with no definitive consensus between them. Currently the experimental studies continue [21], and the recent experimental data of the sum of the quark spin contribution to the nucleon spin is given by [22] ∆Σ = 0.32 ± 0.03 ± 0.03 .…”

Section: Introductionmentioning

confidence: 99%

Quark scalar, axial, and pseudoscalar charges in the Schwinger-Dyson formalism

et al. 2014

View full text Add to dashboard Cite

We calculate the scalar, axial, and pseudoscalar charges of the quark in the Schwinger-Dyson formalism of Landau gauge QCD. It is found that the dressed quark scalar density of the valence quark is significantly enhanced against the bare quark contribution, and the result explains qualitatively the phenomenologically known value of the pion-nucleon sigma term and also that given by lattice QCD. Moreover, we show that the Richardson's interquark potential suppresses the quark scalar density in the Higashjima-Miransky approximation. This fact suggests that the quark scalar density is an observable that is sensitive to quark confinement. For the quark axial charge, we find that it is suppressed due to the gluon dynamics. The result of the quenched analysis agrees qualitatively with the experimental data of the isovector axial coupling constant gA. We show that the suppression of the quenched axial charge is due to a mechanism similar to that of the quark tensor charge. In the Schwinger-Dyson equation with the leading unquenching quark-loop contribution the quark axial charge is more suppressed, due to the anomaly effect. The quark pseudoscalar density is found to be large, and is divergent as the bare quark becomes massless. This result is in agreement with the phenomenological current algebraic analysis, and explains well the dominance of the pion-pole contribution.

show abstract

Quark helicity distributions from longitudinal spin asymmetries in muon–proton and muon–deuteron scattering

Cited by 135 publications

References 44 publications

Nucleon axial and tensor charges with dynamical overlap quarks

Nucleon axial and tensor charges with dynamical overlap quarks

Strangeness Contribution to the Proton Spin from Lattice QCD

Quark scalar, axial, and pseudoscalar charges in the Schwinger-Dyson formalism

Contact Info

Product

Resources

About