ИСТИНА

The N* program in Jefferson Lab is crucial for understanding the strong interaction in the non-perturbative regime and the emergence of hadron mass. Studies of resonance electroexcitation in Nπ electroproduction represent an important part of these efforts. The data on beam spin asymmetry provide unique information on the imaginary part of the interference terms between the electroproduction amplitudes with the longitudinally and transversely polarized virtual photons. The new CLAS results on beam spin asymmetry and polarized structure function σLT' for π0p electroproduction at invariant masses of the final hadrons from the threshold and up to 1.8 GeV and at photon virtualities 0.4 GeV2<Q2<1.0 GeV2 will be presented in the talk. Analyses of these results demonstrated sensitivity of the Legendre moments of the σLT' structure function to the electroexcitation amplitudes of the nucleon resonances in the mass range > 1.6 GeV. Combined studies of beam spin asymmetries and unpolarized cross sections for π0p electroproduction channel will allow us to improve knowledge on Q2-evolution of the resonance electroexcitation amplitudes, in particular, for the resonances in the third resonance region.