885 research outputs found
Deviation pattern approach for optimizing perturbative terms of QCD renormalization group invariant observables
We first consider the idea of renormalization group-induced estimates, in the
context of optimization procedures, for the Brodsky-Lepage-Mackenzie approach
to generate higher-order contributions to QCD perturbative series. Secondly, we
develop the deviation pattern approach (DPA) in which through a series of
comparisons between lower-order RG-induced estimates and the corresponding
analytical calculations, one could modify higher-order RG-induced estimates.
Finally, using the normal estimation procedure and DPA, we get estimates of
corrections for the Bjorken sum rule of polarized deep-inelastic
scattering and for the non-singlet contribution to the Adler function.Comment: 5 pages, proceedings for the XXIII International Baldin Seminar on
High Energy Physics Problems "Relativistic Nuclear Physics and Quantum
Chromodynamics
Low proton structure function, using gluon and pseudoscalar meson clouds in the constituent quark framework
The idea of the meson cloud approach in the chiral quark model has been
extended to include gluon cloud in order to achieve the parton densities in the
nucleon, based on the constitute quark framework. The splitting function of the
quark to the quark-meson and quark-gluon at low value are used to obtain
parton densities in the constituent quark. The phenomenological constituent
model is employed to extract the parton distributions in the proton at low
value. Since we have access to the parton densities at low , we are
able to obtain structure function at low value. The result
is in good agreement with available experimental data and some theoretical
models. To confirm the validity of our calculations, the fraction of total
momentum of proton which is carried by gluon at high and also the
Gottfried sum rule are computed. The results are in good agreement with what
are expected.Comment: 13 pages, 3 figure
Nuclear Parton Densities and Structure Functions
We calculate nuclear parton distribution functions (PDFs), using the
constituent quark model. We find the bounded valon distributions in a nuclear
to be related to free valon distributions in a nucleon. By using improved
bounded valon distributions for a nuclear with atomic number and the
partonic structure functions inside the valon, we can calculate the nuclear
structure function in space. The results for nuclear structure-function
ratio at some values of are in good agreement with the
experimental data.Comment: To be published in Int. Journal of Modern Phys.
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