Origin of difference between<i>u</i>¯ and<i>d</i>¯ partons in the nucleon

Liu, Keh-Fei; Dong, Shao-Jing

doi:10.1103/physrevlett.72.1790

Cited by 202 publications

(235 citation statements)

References 17 publications

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“…The scalar matrix elements of both the u and d quark increase as m q decreases, but the isovector scalar matrix element is not far from unity over the entire quark mass region from light to heavy. This has been interpreted to be related to the Gottfried sum rule violation [45] where it is found experimentally that there are more d antipartons than u antipartons.. …”

Section: Resultsmentioning

confidence: 99%

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Stochastic method with low mode substitution for nucleon isovector matrix elements

et al. 2016

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We introduce a stochastic method with low-mode substitution to evaluate the connected threepoint functions. The isovector matrix elements of the nucleon for the axial-vector coupling g 3 A , scalar couplings g 3 S and the quark momentum fraction x u−d are calculated with overlap fermion on 2+1 flavor domain-wall configurations on a 24 3 ×64 lattice at mπ = 330 MeV with lattice spacing a = 0.114 fm.

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Section: Resultsmentioning

confidence: 99%

“…This has been interpreted [45] to be related to the Gottfried sum rule violation [46] where it is found experimentally that there are more d antipartons than u antipartons. In the isovector quark momentum fraction case, the bare value we obtained at the unitary point on the ensemble mentioned above is…”

Section: Discussionmentioning

confidence: 99%

Stochastic method with low mode substitution for nucleon isovector matrix elements

et al. 2016

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“…Like in the case of the axial coupling constants [12], we also find that the ratio R S = g 3 S /g S,con dips below the SU(6) result of 1/3 as the quark mass becomes lighter. This is interpreted as due to the cloud quark/anti-quark effect and is responsible for theū -d parton difference reflected in the Gottfried sum rule [21]. Only when the cloud degree of freedom is eliminated in the valence approximation [21] where the Fock space is limited to the valence do we recover the SU(6) limit.…”

mentioning

confidence: 99%

“…This is interpreted as due to the cloud quark/anti-quark effect and is responsible for theū -d parton difference reflected in the Gottfried sum rule [21]. Only when the cloud degree of freedom is eliminated in the valence approximation [21] where the Fock space is limited to the valence do we recover the SU(6) limit. This indirectly shows the effect of the cloud quarks in the C.I..…”

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confidence: 99%

πNσterm,s¯sin the nucleon, and the scalar form factor: A lattice study

1996

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We report on a lattice QCD calculation of the πN σ term, the scalar form factor, and N |ss|N . The disconnected insertion part of σ πN is found to be 1.8 ± 0.1 times larger than the connected insertion contribution. The q 2 dependence of σ πN (q 2 ) is about the same as G E (q 2 ) of the proton so that σ πN (2m 2 π )−σ πN (0) = 6.6±0.6 MeV. The ratio y = N |ss|N / N |ūu+dd|N = 0.36 ± 0.03. Both results favor a σ πN ∼ 53 MeV, slightly larger than our direct calculation of σ πN = 49.7 ± 2.6 MeV. We also compute F s and D s and find that the agreement with those from the octect baryon mass splittings crucially depends on the inclusion of the large disconnected insertion. Finally, we give our result for the KN σ term.

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“…[37][38][39] discuss prospects for studying the hadronic tensor by solving the inverse problem on a Euclidean four-point function in the same way as we describe in this work. In contrast to the present study these references do not advocate the Backus-Gilbert technique and do not discuss finite-volume effects, the need for smoothing and the ordered double limit that plays a central role in the present analysis.…”

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confidence: 99%

From deep inelastic scattering to heavy-flavor semileptonic decays: Total rates into multihadron final states from lattice QCD

2017

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We present a new technique for extracting decay and transition rates into final states with any number of hadrons. The approach is only sensitive to total rates, in which all out-states with a given set of QCD quantum numbers are included. For processes involving photons or leptons, differential rates with respect to the non-hadronic kinematics may also be extracted. Our method involves constructing a finite-volume Euclidean four-point function, whose corresponding spectral function measures the decay and transition rates in the infinite-volume limit. This requires solving the inverse problem of extracting the spectral function from the correlator and also necessitates a smoothing procedure so that a well-defined infinite-volume limit exists. Both of these steps are accomplished by the Backus-Gilbert method and, as we show with a numerical example, reasonable precision can be expected in cases with multiple open decay channels. Potential applications include nucleon structure functions and the onset of the deep inelastic scattering regime, as well as semi-leptonic D and B decay rates.

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Origin of difference betweenu¯ andd¯ partons in the nucleon

Cited by 202 publications

References 17 publications

Stochastic method with low mode substitution for nucleon isovector matrix elements

Stochastic method with low mode substitution for nucleon isovector matrix elements

πNσterm,s¯sin the nucleon, and the scalar form factor: A lattice study

From deep inelastic scattering to heavy-flavor semileptonic decays: Total rates into multihadron final states from lattice QCD

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