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Résumé |
I will consider polarized inelastic electron-nucleon scattering at low momentum transfer,
in the Witten-Sakai-Sugimoto model of holographic QCD. I will focus, in particular, on
resonance production contributions to the nucleon spin structure functions. I will
compute the helicity amplitudes for nucleon-resonance transitions and the resonance
contributions to the neutron and proton generalized spin polarizabilities. Extrapolating
the model parameters to realistic QCD data, the analysis, triggered by recent
experimental results from Jefferson Lab, shows that the Delta(1232) resonance gives the
dominant contribution to the spin polarizabilities at low momentum transfer. The
contribution is negative and increases towards zero as the momentum transfer increases. |
