Flavor asymmetry of light quarks in the nucleon sea

Garvey, G. T.; Peng, J. C.

doi:10.1016/s0146-6410(01)00155-7

Cited by 141 publications

(70 citation statements)

References 182 publications

(235 reference statements)

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“…A major surprise in the flavor structure of the nucleon sea was found when deep-inelastic scattering (DIS) and Drell-Yan experiments showed that theū andd in the proton have strikingly different Bjorken-x dependence [1][2][3][4][5][6]. Theoretical models which can explain this flavor asymmetry also have specific predictions on other aspects of spin and flavor structures of sea quarks.…”

Section: Introductionmentioning

confidence: 99%

Extraction of the intrinsic light-quark sea in the proton

Chang

Peng

2015

Phys. Rev. D

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The HERMES collaboration recently reported a reevaluation of the strange-quark parton distribution, S(x), based on kaon production in semi-inclusive deep-inelastic scattering. Two distinct results on S(x)at the x > 0.1 region, one with a sizable magnitude and another with a vanishing content, were reported.We show that the latter result is due to a particular assumption adopted in the analysis. The impact of the new HERMES S(x) result on the extraction of intrinsic light-quark sea in the proton is discussed. Given the large uncertainty in the kaon fragmentation function, we find that the latest HERMES data do not exclude the existence of a significant intrinsic strange-quark sea in the proton. The x dependence of the (s +s)/(ū +d) ratio is also in qualitative agreement with the presence of intrinsic strange-quark sea.

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Section: Introductionmentioning

confidence: 99%

Extraction of the intrinsic light-quark sea in the proton

Chang

Peng

2015

Phys. Rev. D

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“…Thus the observation of an excessd overū antiquarks in the proton [23], which has been described in terms of a nπ + configuration [24], might alternately be described in terms of an [udud]d component in the proton. While the N * (1440) may contain significant N π and ∆π components, its unusual properties might also be described in terms of admixtures of colored quark cluster configurations.…”

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confidence: 99%

ss¯Component of the Proton and the Strangeness Magnetic Moment

2005

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A complete analysis is given of the implications of the empirical indications for a positive strangeness magnetic moment µs of the proton on the possible configurations of the uudss component of the proton. A positive value for µs is obtained in the ss configuration where the uuds subsystem is in an orbitally excited state with [4]F S [22]F [22]S flavor-spin symmetry, which is likely to have the lowest energy. The configurations in which thes is orbitally excited, which include the conventional K + Λ 0 configuration, with exception of that in which the uuds component has spin 2, yield negative values for µs. The hidden strangeness analogues of recently proposed quark cluster models for the θ + pentaquark give differing signs for µs.Three recent experiments on parity violation in electron-proton scattering suggest that the strangeness magnetic moment of the proton µ s is positive [1,2,3]. In contrast theoretical calculations have led to negative values for this observable, with but few exceptions [4,5,6,7,8,9]. Here the implications of the empirical result for the configuration of the constituents of the proton is considered by a calculation of µ s for all positive parity configurations of the uudss system with one constituent in the first orbitally excited state, which may be contained in the proton. The results are given in the form of simple general expressions, in which µ s is proportional to the ss probability of the configuration.It is shown that µ s is positive in the uudss configuration, which is likely to have the lowest energy, where thes quark is in the ground state and the uuds system is in the P −state. If in contrast the strange antiquark is in the P −state and the 4 quarks are in their ground state the strangeness magnetic moment is negative (except for the energetically unfavored case where the total spin of the uuds state equals 2). These configurations correspond to that of a fluctuation of the proton into a kaon and a strange hyperon, which is well known to lead to a negative value for the strangeness magnetic moment [10,11,12,13].Several intriguing configurations [14,15,16] for the system of 4 light flavor quarks and a strange antiquarks have been proposed to explain the structure of the (tentative) θ + pentaquark. Below their hidden strangeness analogues are considered from the point of view of the strangeness magnetic moment. While the diquarkdiquark configurations suggested in refs. [14,15] Table 1 [17]. The requirement of positive parity requires that for these configurations the strange antiquark has to be in the P −state.If in contrast the strange antiquarks is in its ground state, the uuds system has to be in the P −state in order that the combination have positive parity. In this case the symmetry of the spatial state of the 4-quark system is reduced to Table I [17].In the quark model the strangeness magnetic moment is defined as the matrix element of the operatorwhereŜ is the strangeness counting operator, with eigenvalue +1 for s and −1 fors quarks and m s is the constituent mass of...

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“…The reason becomes clear if one compares the predictions of the CQSM with those of the naive meson cloud convolution model. As is widely known, the NMC observationd(x) −ū(x) > 0 in the proton can be explained equally well by the CQSM and by the meson cloud model [68], [69], [70]. A simple intuitive argument, however, indicates that the latter model would generally predict both of ∆ū(x) and ∆d(x) is small.…”

Section: Su(2) Cqsm Su(3) Cqsm Experimentsmentioning

confidence: 86%

Light-flavor sea-quark distributions in the nucleon in the SU(3) chiral quark soliton model. I. Phenomenological predictions

Wakamatsu

2003

Phys. Rev. D

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Theoretical predictions are given for the light-flavor sea-quark distributions in the nucleon including the strange quark ones on the basis of the flavor SU(3) version of the chiral quark soliton model. Careful account is taken of the SU(3) symmetry breaking effects due to the mass difference ∆m s between the strange and nonstrange quarks, which is the only one parameter necessary for the flavor SU(3) generalization of the model. A particular emphasis of study is put on the light-flavor

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Flavor asymmetry of light quarks in the nucleon sea

Cited by 141 publications

References 182 publications

Extraction of the intrinsic light-quark sea in the proton

Extraction of the intrinsic light-quark sea in the proton

ss¯Component of the Proton and the Strangeness Magnetic Moment

Light-flavor sea-quark distributions in the nucleon in the SU(3) chiral quark soliton model. I. Phenomenological predictions

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