89 research outputs found
Photon plus heavy quark production in high energy collisions within the target rest frame formalism
We apply the target rest frame formalism to photon + heavy quark production
cross section in hadronic collisions at high energies. We investigate the
dependence of the production cross section on the photon and quark rapidities
and transverse momenta. It is shown that the photon transverse momentum
spectrum is a sensitive probe of color dipole scattering amplitude. The
theoretical results are compared to Tevatron measurements of the differential
\gamma + c + X and \gamma + b + X production cross sections at 1.96 TeV. An
analysis for proton-proton and proton-lead collisions at the LHC regime is also
performed.Comment: 6 pages, 3 figures. Version to be published in Physical Review
Parton saturation effects to the Drell-Yan process in the color dipole picture
We report on the results obtained in the study of the parton saturation
effects, taken into account through the multiscattering Glauber-Mueller
approach, applied to the Drell-Yan (DY) process described in the color dipole
picture. As a main result, one shows that those effects play an important role
in the estimates of the DY differential cross section atRHIC energies.Comment: To appear in the proceedings of the VIII International Workshop on
Hadron Physics 200
Polarized Deep Inelastic Scattering Off the "Neutron" From Gauge/String Duality
We investigate deep inelastic scattering off the polarized "neutron" using
gauge/string duality. The "neutron" corresponds to a supergravity mode of the
neutral dilatino. Through introducing the Pauli interaction term into the
action in space, we calculate the polarized deep inelastic
structure functions of the "neutron" in supergravity approximation at large t'
Hooft coupling and finite with . In
comparison with the charged dilatino "proton," which has been obtained in the
previous work by Gao and Xiao, we find the structure functions of the "neutron"
are power suppressed at the same order as the ones of the "proton." Especially,
we find the Burkhardt-Cottingham-like sum rule, which is satisfied in the work
by Gao and Xiao, is broken due to the Pauli interaction term. We also
illustrate how such a Pauli interaction term can arise naturally from higher
dimensional fermion-graviton coupling through the usual Kaluza-Klein reduction.Comment: 21pages,5figures, published versio
QCD evolution and skewedness effects in color dipole description of DVCS
We show the role played by QCD evolution and skewedness effects in the DVCS
cross section at large within the color dipole description of the process
at photon level. The dipole cross section is given by the saturation model,
which can be improved by DGLAP evolution at high photon virtualities. We
investigate both possibilities as well as the off-forward effect through a
simple phenomenological parametrisation. The results are compared to the recent
ZEUS DVCS data.Comment: LaTeX, 6 pages, 5 Figs. Vers 2: Minor modifications. Accepted by EPJ
Dilepton distributions at backward rapidities
The dilepton production at backward rapidities in and collisions
at RHIC and LHC energies is investigated in the dipole approach. The results
are shown through the nuclear modification ratio considering
transverse momentum and rapidity spectra. The dilepton modification ratio
presents interesting behavior at the backward rapidities when compared with the
already known forward ones, since it is related with the large kinematical
region that is being probed. The rapidity dependence of the nuclear
modification ratio in the dilepton production is strongly dependent on the
Bjorken behavior of the nuclear structure function ratio
. The transverse momentum dependence at
backward rapidities is modified due to the large nuclear effects: at RHIC
energies, for instance, the ratio is reduced as increases,
presenting an opposite behavior when compared with the forward one. It implies
that the dilepton production at backward rapidities should carry information of
the nuclear effects at large Bjorken , as well as that it is useful to
investigate the dependence of the observables in this kinematical regime.Comment: 15 pages, 6 figures. Version published in the Phys. Rev.
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