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Hard exclusive processes beyond the leading twist

Abstract : This thesis deals with the computation of the helicity amplitudes of the exclusive diffractive rho meson leptoproduction in the perturbative Regge limit beyond the leading twist. The understanding of such exclusive processes in terms of the elementary constituents of QCD is a serious challenge to understand the hadronic structure. We present two new phenomenological models based on the kT-factorization of the helicity amplitudes in a γ*(λ) → ρ(λ') impact factor, where λ and λ' denote the polarizations of the virtual photon and the rho meson, and the nucleon target impact factor. The γ*(λ) → ρ(λ') impact factors are then computed using the collinear factorization of the rho meson soft part. The first model relies on the combination of the results respectively up to twist 2 and twist 3 for the impact factors where both polarizations are longitudinal or transverse, with a model for the nucleon impact factor and a model for the distribution amplitudes of the rho meson. In the second approach presented in this thesis, we derive these impact factors in impact parameter space and show that the color dipole scattering amplitude with the nucleon factorizes, allowing to use our results in combination with dipole cross-section models. We get a very good agreement with the data from H1 and ZEUS collaborations for virtualities higher than a few GeV. We discuss our results and compare them to other models.
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Submitted on : Thursday, August 29, 2013 - 11:19:18 AM
Last modification on : Wednesday, October 14, 2020 - 3:42:33 AM
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  • HAL Id : tel-00855281, version 1



Adrien Besse. Hard exclusive processes beyond the leading twist. Other [cond-mat.other]. Université Paris Sud - Paris XI; National centre for nuclear research (Otwock-Świerk), 2013. English. ⟨NNT : 2013PA112106⟩. ⟨tel-00855281⟩



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