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Nuclear charm and bottom production a comparison among high energy approaches
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NUCLEAR CHARM AND BOTTOM PRODUCTION: A COMPARISON
AMONG HIGH ENERGY APPROACHES
V.P. Gonc?alves 1, M.V.T. Machado 1, 2
1 Instituto de F??sica e Matema?tica, Universidade Federal de Pelotas
Caixa Postal 354, CEP 96010-090, Pelotas, RS, Brazil
2 High Energy Physics Phenomenology Group, GFPAE, IF-UFRGS
Caixa Postal 15051, CEP 91501-970, Porto Alegre, RS, Brazil
ABSTRACT
We calculate the nucleon and nuclear photoproduction cross sections for heavy quarks within
the k⊥-factorization formalism, considering the current high energy approaches which include
nuclear and saturation effects. Our results demonstrate that a future experimental analysis of
this process would allow to constraint the QCD dynamics at high energies.
1 Introduction
The electron-proton (ep) collider at HERA has opened up a new kinematic regime in the study
of the deep structure of the proton and, in general, of hadronic interactions. This regime is
characterized by small values of the Bjorken variable x = Q2/s, where Q2 is the momentum
transfer and
√
s is the center-of-mass energy. The experimental results from HERA have shown
a striking rise of the proton structure function F2(x,Q
2) for values x 10?2, which implies that
the cross section increases faster than logarithmically on energy. This high energy behavior in
the hard-scattering regime is expected if the underlying dynamics is driven by self-interacting
massless vector bosons, the gluons. Thus, the steep rise of F2 certainly confirms one of the basic
predictions of perturbative QCD. As the predictions of the collinear and the k⊥-factorization
approaches, relying on different assumptions, agree with the measurements of the inclusive
quantities, one current open question is: what is the correct QCD dynamics at high energies?
In the collinear factorization approach [1] all partons involved are assumed to be on mass
shell, carrying only longitudinal momenta, and their transverse momen
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