Dipole Approach
Mostrando 13-24 de 40 artigos, teses e dissertações.
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13. Confronting color dipole and intrinsic kT approaches in D-Y dilepton production
We study the Drell-Yan dilepton production in proton-nucleus collisions at RHIC energies. We use two different approaches: the usual intrinsic transverse momentum approach at NLO in the infinitum momentum frame; and the color dipole in the target rest frame. We compare both formalisms at backward rapidities (proton as a target). At forward rapidities, we use
Brazilian Journal of Physics. Publicado em: 2008-09
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14. Deeply virtual compton scattering in color dipole formalism
In this contribution we summarize recent investigations on the deeply virtual Compton Scattering (DVCS) within the color dipole approach. The color dipole cross section is implemented through the phenomenological saturation model. The role played by its QCD evolution and skewedness effects in the DVCS cross section are discussed. The results are compared wit
Brazilian Journal of Physics. Publicado em: 2007-07
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15. High density QCD through eletromagnetic probes
In this work we investigate the high density QCD system through the dilepton production. First, the dilepton production in the color dipole approach is investigated, studing perturbative unitarity corrections to the dipole cross section and its consequence in the transverse momentum distribution of the dileptons at RHIC and LHC energies. Second, the dilepton
Brazilian Journal of Physics. Publicado em: 2007-07
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16. An extraction of the skewing factor from DESY-HERA data
In this contribution we present recent investigation on the extraction of the skewing factor, defined as the ratio of the imaginary parts of the amplitudes Im ${\cal A}$(gamma* p ® g* p)/ Im ${\cal A}$(gamma* p ® g p). This factor is extracted from the data using the recent DVCS and the inclusive inelastic
Braz. J. Phys.. Publicado em: 2007-06
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17. Trajectory effects in coulomb excitation
We compare the cross sections for Coulomb excitation of multiple giant dipole resonances in 208Pb + 208Pb scattering using Coulomb trajectories and straight-line trajectories that have the same point of closest approach as the Coulomb one. We find the effects of the Coulomb deflection relative to the straight line trajectory to be small at incident energies
Brazilian Journal of Physics. Publicado em: 2006-12
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18. The spreading width calculation of giant resonances with a semi-microscopic approach
We have proposed a semi-microscopic approach to calculate the two particles - two holes (2p - 2h) spreading width of giant resonances. Our proposal has been based in a hybrid method that implements the statistical multistep compound theory of Feshbach, Kerman and Koonin (FKK), widely and successful used in nuclear reactions mechanisms, in order to include re
Brazilian Journal of Physics. Publicado em: 2006-12
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19. Production of 1s2s2p4P states by transfer-loss cascades in O5+ collisions with he and H2 targets
Single differential cross-sections for transfer-loss (TL) leading to the production of O5+(1s2s³S)nl4L states were computed for 0.2-1.2 MeV/u collisions of O5+(1s²2s) ions with He and H2 targets. At these collision energies, 1s loss is significant and electron transfer to n = 3-4 levels is dominant. Furthermore, due to spin conservation, quartet states can
Brazilian Journal of Physics. Publicado em: 2006-06
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20. Description of decay mechanisms of the giant dipole resonances with a RPA + FKK approach
The decay mechanisms of giant resonances have been revisited to investigate the isoscalar dipole resonance in 208Pb nucleus.
Brazilian Journal of Physics. Publicado em: 2005-09
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21. Armazenamento e distribuição de pulsos ópticos com conversão em múltiplos comprimentos de onda
Based in the effect of the Electromagnetically Induced Transparency (EIT) and the storage of light in atomic medium, we propose multi-wavelength optical pulse conversion. Starting from coupled Maxwell-Bloch equations, we simulate the propagation of the optical pulses resonant with electric dipole transition in the atomic system. Considering a three level
Publicado em: 2005
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22. Weighted oscillator strengths and lifetimes for the neutral oxygen spectrum, O I
The weighted oscillator strengths (gf) and the lifetimes for O I presented in this work were obtained in a multiconfiguration Hartree-Fock relativistic (HFR) approach. In this calculation, the electro-static parameters were optimized by a least-squares procedure, in order to improve the adjustment to experimental energy levels. This method produces gf-values
Brazilian Journal of Physics. Publicado em: 2001-03
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23. Bragg-Surface diffraction (BSD) : high resolution microprobe to study ion implanted semiconductors / Forças de oscilador ponderadas e tempos de vida para os espectros de Si II, Si VIII e SI IX
The principal objective of this work is to present the weighed oscillator strengths (gf) and the lifetimes for all the eletric dipole transitions experimentally known for the íons of Si II, Si VIII VIII and Si IX. The interpretation of the calculation of these two values is for instance of fundamental importance in the astrophysics, because the silicon in y
Publicado em: 2000
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24. Internal electrostatic potentials in bilayers: measuring and controlling dipole potentials in lipid vesicles.
The binding and translocation rates of hydrophobic cation and anion spin labels were measured in unilamellar vesicle systems formed from phosphatidylcholine. As a result of the membrane dipole potential, the binding and translocation rates for oppositely charged hydrophobic ions are dramatically different. These differences were analyzed using a simple elect