Polarized Quarks, Gluons and Sea in Nucleon Structure Functions

Abstract

We perform a NLO analysis of polarized deep inelastic scattering data to test two different solutions to the so-called spin crisis, one of them based on the axial gluon anomaly and consistent with the Bjorken sum rule, and another in which the defects in the spin sum rules and in the Gottfried sum rule are related. In this case a defect is also expected for the Bjorken sum rule. The first solution is slightly favoured by the SLAC El54 results, but both options seem to be consistent with the CERN SMC data. §1. IntroductionThe EMC experiment on gf(x) 1) has given for the first moment of the spin dependent proton structure function g{ ' (x) a value much smaller than the prediction of the Ellis-Jaffe sum rule 2) for the proton (we use a3 = GA/G v = 1.2573 ± 0.0028 and a8 = 3F -D = 0.579 ± 0.025 3 »),This has stimulated considerable experimental activity in measuring the polarized structure functions (SF) gf(x), g~(x) (g~He) and gr(x).4)~6) From the theoretical point of view, the hypothesis has been formulated 7) that a relevant isoscalar contribution, related, in the chiral-invariant factorization scheme, 8) to a large gluon polarization, contributes to Eq. (2) at 0(0 8 ) as rp(Q2) = ~ (a 3 + a8 + ~ao(Q2)) (1 _ 08(Q2)) _ 08(Q2) LlG(Q2) . (3) 1 12 3 3 7r 67rDownloaded from https://academic.oup.

Is the polarized antiquark sea in the nucleon flavor symmetric?

“…This is in contrast to the assumption (1) made in the literature [1][2][3][4][5][6][7][8][12][13][14] that all the three ∆q's have the same sign.…”

“…Several comprehensive analyses of the polarized deep inelastic scattering (DIS) data, based on next-to-leading-order quantum chromodynamics (QCD), have appeared recently [1][2][3][4][5][6][7][8][9][10][11]. In these analyses the polarized parton density functions (PDFs) are either written in terms of the well-known parameterizations of the unpolarized PDFs or parameterized independently, and the unknown parameters are determined by fitting the polarized DIS data.…”

“…In these analyses the polarized parton density functions (PDFs) are either written in terms of the well-known parameterizations of the unpolarized PDFs or parameterized independently, and the unknown parameters are determined by fitting the polarized DIS data. Additional simplifying assumptions are often made; the one that has been widely used in the literature [1][2][3][4][5][6][7][8] is ∆ū = ∆d = λ∆s,…”

A Positive Test for Fermi–dirac Distributions of Quark–partons

“…We wish to compare our evaluation of the first two moments of the non-singlet polarized distributions with a previous analysis of the same data [27] and with the result found in the NLO analysis of Ref. [25].…”

“…Table 4: The values of the first and second moment of the non-singlet part of g p 1 with ∆G free, obtained with the present parameterization (PP), are compared with the same quantities from quantum statistical distributions (ST) and from Ref. [25,27]. The values from Ref.…”