Quarks and gluons in hadrons and nuclei Page: 20 of 31
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magnitude of es by 0.03, and so es = -0.20 0.09 should replace Eq. (50).
However, it does not seem to be widely appreciated that the F/D of Ref. 16
was much constrained by an outdated value of the neutron lifetime, and that Ref.
16 chose "to omit from (their) fit the neutron decay correlation (which yields)
gA = 1.258 0.009, which differs significantly from the result 1.239 0.009
required by the neutron lifetime measurements". The value accepted as correct
today18 differs by some 3a from the old value, and this, together with other data
on hyperon beta decays, i5,8,19 shows that F/D is much smaller than the old value.
Flavor symmetry breaking causes a spread in values of F/D, depending on which par-
tial set of data one uses; indeed, the symmetry breaking even calls into question
the utility of the F/D parameter,20 and so Refs. 17 and 21 set up their analyses
without direct reference to F/D. Translating their work into F/D, one finds that
the value subsumed in Ref. 17 is F/D = 0.56 consistent with that implicit in Ref.
21 and, within errors, with the fitted value in Ref. 22. Reference 23 obtained an
even smaller value of F/D = 0.545 0.02. Recent improvements in the En beta
decay data, in particular, may raise F/D to 0.58 (Ref. 24), but nowhere as high as
the 0.63 used previously.
The magnitudes for es implied by these values for F/D are
F/D = 0.548 0.01 +s = -0.12 0.06 Ref. 23 (51)
F/D = 0.58 0.01 + es = -0.15 0.08 Ref. 24 (52)
Thus we see that the magnitude of the (negative) strange polarization may be
only half as big as that previously assumed. The QCD-corrected value of the
Ellis-Jaffe sum rule falls from 0.19 (the cited value when F/D = 0.63) to 0.17 if
F/ = 0.56, thereby reducing the statistical significance of the much-advertised
failure of this sum rule.
What independent information exists on es? Elastic neutrino-proton scatter-
ing can, in principle, probe this quantity,32 and a fit to these data give
es = -0.15 0.09.
Note that this agrees with the revised value in the present paper arising from the
smaller F/D and the revised EMC integral (Ref. 29).
One should also be aware that the neutrino experiment is also consistent with
es = 0 which, in advance of the controversial EMC experiment, was the expectation.
Flavor-changing weak interactions, such as neutron beta decay, can yield
- =1.25 = eu - Ad,
while the zero momentum limit of vp + p can probe
OJA(0) = Au - ed - es 9 - 12,
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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/m1/20/: accessed March 21, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.