15,873 research outputs found
Leptoproduction of charm revisited
We calculate the energy--momentum distribution of the charmed quarks produced
in neutrino reactions on protons, quantifying the importance of mass and
current non--conservation effects. We study the strange and charm distributions
probed in neutrino interactions in the presently accessible kinematical region.
Some ambiguities inherent to the extraction of the parton densities from dimuon
data are pointed out.Comment: 9 pages, DFTT 72/9
On the low x behaviour of nuclear shadowing
We calculate the x dependence of nuclear shadowing at moderate values of Q^2
by using HERA diffractive data and, for consistency, F2 parameterization of
ZEUS. We show that no decrease of shadowing occurs down to very low x (x =
10^-4).Comment: 9 pages, submitted on june for publicatio
Longitudinal and Transverse Nuclear Shadowing
Nuclear shadowing arises from multiple scattering of the hadronic
fluctuations of the virtual photon in a nucleus. We predict different
longitudinal and transverse shadowing and an A-dependence of R which can be up
to a 50% effect. The possibility of detecting nuclear effects on R at HERA is
discussed.Comment: latex, 6 page
Extracting the Strange Density from
We present a QCD analysis of the strange and charm contributions to the
neutrino deep inelastic structure function . We show that next-to-leading
order effects, which are relatively important for , play a lesser role in
the case of . The neutrino--antineutrino difference provides a new determination of the strange density, which
exhibits some advantages with respect to other traditional methods.Comment: 12 page
A new global analysis of deep inelastic scattering data
A new QCD analysis of Deep Inelastic Scattering (DIS) data is presented. All
available neutrino and anti-neutrino cross sections are reanalysed and included
in the fit, along with charged-lepton DIS and Drell-Yan data. A massive
factorisation scheme is used to describe the charm component of the structure
functions. Next-to-leading order parton distribution functions are provided. In
particular, the strange sea density is determined with a higher accuracy with
respect to other global fits.Comment: 51 pages, 18 figure
Unitarization of Structure Functions at Large
We discuss the effects of the -channel unitarization on the and
dependence of structure functions. The unitarization is implemented at
the level of photoabsorption cross sections by resorting to the light--cone
wave functions of virtual photons and to the diagonalization property of the
scattering matrix in a basis of Fock states of the photon with fixed transverse
size. Triple pomeron effects are also explicitly taken into account. We find
large unitarity corrections to the structure functions at . The
results are in very good agreement with the existing NMC and the preliminary
HERA data.Comment: 12 page
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