Quarks and gluons in hadrons and nuclei Page: 17 of 31
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Un _ Zd-eu+(-2Au+ed+Res) (42)
where R = md/ms = 3/5. The electrical neutrality of the sea tends to shield its
contribution. A detailed fit is made in Ref. 12.
The (gAgV) for the octet of baryons also relate to the spin polarized proba-
bilities such as
= euv - ev + -5edv, (43)
where we used Eq. (41). Thus immediately
edv = -0.25; euv = 1. (44)
In the 56 NRQM one would have3
edv = -1/3; euv = 4/3; euv + Adv = 1, (45)
and the entire spin polarization comes from the quarks. However, from Eq. (44),
we see that
nuv + dv = 3/4, (46)
and so, in advance of the EMC data, only naive "quarkists" would have expected
100% for eqv. Anyone who worked with four-component spinors, of which the MIT bag
is a specific model example, knew that the "orbital dilution" in the lower compo-
nents played an essential role.13 In fact, the eqv expectation is even less than
Eq. (46). When one makes a best fit to all of the baryon octet gA/gV, one finds
eqv(= 3F-D) = 0.55 0.10. (47)
Note the appearance of F and D which summarizes the gA/gV. This parameter will
appear later. Note that many analyses of the polarization data use2,6,10,15 F/D =
0.63 (Ref. 16). However, this value fitted a value of the neutron lifetime that
we now know to have been incorrect.17'18 The correct current value 19-2s is lower
than 0.63 and is dependent upon assumptions about SU(3) flavor breaking.
The earliest predictions for the deep inelastic polarization asymmetry in the
valence-dominated region assumed that all eq and q (valence) have the same x
dependence. Thus (see Refs. 3 and 4 for origins of these formulae)
An (x) =4Ad + au + 0,
(the zero following immediately from Eq. (41)) and
The prediction that Ap > 0 is non-trivial as a priori it could be anywhere in the
range -1 < A c +1. The presence of a qq sea as x + 0 was expected to cause A(x +
0) + 0. The other qualitative expectation26,27 was that A(x + 1) + 1 as follows.
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Close, F. E. Quarks and gluons in hadrons and nuclei, article, December 1, 1989; Tennessee. (https://digital.library.unt.edu/ark:/67531/metadc1058782/m1/17/: accessed March 25, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.