5,087 research outputs found
On the NuTeV anomaly and the asymmetry of the strange sea in the nucleon
Our recent theoretical analysis based on the flavor SU(3) chiral quark
soliton model predicts fairly large particle-antiparticle asymmetry of the
strange sea in the nucleon. We point out that the predicted magnitude of
asymmetry is large enough to solely resolve the so-called NuTeV anomaly on the
fundamental parameter in the standard model.Comment: 9 pages, 1 figure, revised final version to appear in Phys. Rev.
On the new COMPASS measurement of the deuteron spin-dependent structure function
Very recently, a new measurement of the deuteron spin-dependent structure
function was reported by the COMPASS group. A main change from the
old SMC measurement is a considerable improvement of the statistical accuracy
in the low region . We point out that the new COMPASS
data for as well as their QCD fits for and are all remarkably close to our theoretical predictions
given several years ago based on the chiral quark soliton model.Comment: Errors in Fig.4 were corrected. Version accepted for publication in
Physics Letters
On the D-term of the nucleon generalized parton distributions
It is known that some of the deeply-virtual-Compton-scattering observables,
for instance, the beam-charge asymmetry in the hard electroproduction of real
photons on the nucleon, are extremely sensitive to the magnitude of D-term
appearing in the parameterization of the generalized parton distributions. We
report a theoretical analysis of both the isoscalar and isovector parts of the
nucleon D-term within the framework of the chiral quark soliton model, without
recourse to the derivative expansion type approximation used in previous works.Comment: 10 pages, 2 eps-figures, small improvements, version to appear in
Phys. Lett.
Chiral-odd distribution functions in the chiral quark soliton model
The recent measurements of azimuthal single spin asymmetries by the HERMES
collaboration has opened up new possibility to measure chiral-odd distribution
functions through semi-inclusive deep-inelastic scatterings. Here, predictions
are given for the twist-2 and twist-3 chiral-odd distribution functions of the
nucleon within the framework of the chiral quark soliton model, with full
inclusion of the vacuum polarization effects as well as the subleading
corrections. The importance of the vacuum polarization effects is demonstrated
by showing that the so-called Soffer inequality holds not only for the quark
distributions but also for the antiquark ones.Comment: 12 pages, latex, 5 eps_fi
On the two remaning issues in the gauge-invariant decomposition problem of the nucleon spin
The question whether the total gluon angular momentum in the nucleon can be
decomposed into its spin and orbital parts without conflict with the
gauge-invariance principle has been an object of long-lasting debate. Despite a
remarkable progress achieved through the recent intensive researches, the
following two issues still remains to be clarified more transparently. The
first issue is to resolve the apparent conflict between the proposed
gauge-invariant decomposition of the total gluon angular momentum and the
textbook statement that the total angular momentum of the photon cannot be
gauge-invariantly decomposed into its spin and orbital parts. We show that this
problem is also inseparably connected with the uniqueness or non-uniqueness
problem of the nucleon spin decomposition. The second practically more
important issue is that, among the two physically inequivalent decompositions
of the nucleon spin, i.e. the "canonical" type decomposition and the
"mechanical" type decomposition, which can we say is more physical or closer to
direct observation ? In the present paper, we try to answer both these
questions as clearly as possible.Comment: The version to appear in European Physical Journal
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