Measurement of R = sigma_L / sigma_T and the Separated Longitudinal and   Transverse Structure Functions in the Nucleon Resonance Region
  We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.2 < Q^2 < 5.5 GeV^2. The data have been used to accurately perform 167 Rosenbluth-type longitudinal / transverse separations. The precision R = sigma_L / sigma_T data are presented here, along with the first separate values of the inelastic structure functions F_1 and F_L in this regime. The resonance longitudinal component is found to be significant, both in magnitude and in the existence of defined mass peaks. Additionally, quark-hadron duality is here observed above Q^2 = 1 GeV^2 in the separated structure functions independently. 
The Jefferson Lab Hall C E94-110 Collaboration: Y. Liang, V. Tvaskis,   M.E. Christy, A. Ahmidouch, C. S. Armstrong, J. Arri...