10,534 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
Charm and bottom production in inclusive double Pomeron exchange in heavy ion collisions at the LHC
The inclusive double Pomeron exchange cross section for heavy quark pair
production is calculated for nucleus-nucleus collisions at the LHC. The present
estimate is based on hard diffractive factorization, corrected by absorptive
corrections and nuclear effects. The theoretical uncertainties for nuclear
collisions are investigated and a comparison to other approaches is presented.
The production channels producing a similar final state configuration are
discussed as well.Comment: 7 pages, 3 tables. Final version to be published in Physical Review
Studies of the photoionization cross sections of CH_4
We present cross sections and asymmetry parameters for photoionization of the 1t_2 orbital of CH_4 using staticâexchange continuum orbitals of CH^+_4 to represent the photoelectron wave function. The calculations are done in the fixedânuclei approximation at a single internuclear geometry. To approximate the nearâthreshold behavior of these cross sections, we assumed that the photoelectron spectrum is a composite of three electronic bands associated with the JahnâTeller components of the distorted ion. The resulting cross sections reproduce the sharp rise seen at threshold in the experimental data and are in good agreement with experiment at higher energy. The agreement between the calculated and measured photoelectron asymmetry parameters is, however, less satisfactory
Preparation of polymer-based nanocomposites by different routes
Since the eighties, polymeric nanocomposites have been intensely investigated due
to the performance improvement achieved when a small amount of nanosized particles
are added to a polymer matrix. The remarkable changes on physical and mechanical
properties of polymers due to the addition of inorganic solid nanoparticles (typically in
form of fibres, flakes, spheres or fine particles) is explained by the huge surface area,
which increases the interaction between the nanoparticle and the polymer. Moreover,
nanocomposites can be produced using conventional polymer processing techniques,
which makes them particularly interesting from the production point of view. Therefore,
this chapter will make an overview about different routes to prepare polymer-based
nanocomposites by extrusion, mainly synthesis of nanoparticles by sol-gel reactions and
dispersion of clays in polymer matrices
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