359 research outputs found
Parton distribution functions in nuclei
Optimum nuclear parton distributions are determined by an analysis of muon
and electron deep inelastic scattering data. Assuming simple A dependence and
polynomial functions of x and 1-x for nuclear modification of parton
distributions, we determine the initial distributions by a chi^2 analysis.
Although valence-quark distributions are relatively well determined except for
the small-x region, antiquark distributions cannot be fixed at medium and large
x. It is also difficult to fix gluon distributions.Comment: 1+4 pages, LaTeX2e, ws-p8-50x6-00.cls, 4 eps figures. Talk given at
the 9th International Workshop on Deep Inelastic Scattering, Bologna, Italy,
April 27 - May 1, 2001. To be published in proceedings. Computer codes for
the nuclear parton distributions could be obtained from
http://hs.phys.saga-u.ac.jp Email: [email protected],
[email protected], [email protected]
Parametrization of nuclear parton distributions
Optimum nuclear parton distributions are obtained by analyzing available
experimental data on electron and muon deep inelastic scattering (DIS). The
distributions are given at Q^2=1 GeV^2 with a number of parameters, which are
determined by a chi^2 analysis of the data. Valence-quark distributions are
relatively well determined at medium x, but they are slightly dependent on the
assumed parametrization form particularly at small x. Although antiquark
distributions are shadowed at small x, their behavior is not obvious at medium
x from the F_2 data. The gluon distributions could not be restricted well by
the inclusive DIS data; however, the analysis tends to support the gluon
shadowing at small x. We provide analytical expressions and computer
subroutines for calculating the nuclear parton distributions, so that other
researchers could use them for applications to other high-energy nuclear
reactions.Comment: 1+11 pages, LaTeX, amsmath.sty, wrapfig.sty, graphicx.sty, ias.cls,
ias.sty, pramana.sty, pmana10.sty, pbib.sty, times.sty, 9 eps figures.
Invited talk given at the International Symposium on Nuclear Physics, Mumbai,
India, Dec. 18-22, 2000, to be published in proceedings. Complete postscript
file is available at http://www-hs.phys.saga-u.ac.jp Email:
[email protected], [email protected],
[email protected]
Nuclear modification in the structure function
Nuclear shadowing in the structure function is investigated as a
possible test of shadowing models. The shadowing is studied in two
different theoretical models: a parton-recombination model with rescaling
and an aligned-jet model. We find that predictions in these models differ
completely in the small region. It suggests that the shadowing could
be used for discriminating among different models, which produce similar
shadowing behavior in the structure function .Comment: 5 pages, Latex, Fig.1 is not included, Talk given at the IV
International Symposium on ``Weak and Electromagnetic Interactions in Nuclei"
Osaka, Japan, June 12 - 16, 1995, Complete postscript file including the
figure is available at
ftp://ftp.cc.saga-u.ac.jp/pub/paper/riko/quantum1/saga-he-82.ps.gz or at
http://www.cc.saga-u.ac.jp/saga-u/riko/physics/quantum1/structure.htm
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