Parton-hadron duality in unpolarized and polarized structure functions

We study the phenomenon of parton-hadron duality in both polarized and unpolarized electron proton scattering using the HERMES and the Jefferson Lab data, respectively. In both cases we extend a systematic perturbative QCD based analysis to the integrals of the structure functions in the resonance region. After subtracting target mass corrections and large x resummation effects, we extract the remaining power corrections up to order 1/Q². We find a sizable suppression of these terms with respect to analyses using deep inelastic scattering data. The suppression appears consistently in both polarized and unpolarized data, except for the low Q² polarized data, where a large negative higher twist contribution remains. A similar trend is found by using phenomenological parametrizations of the data, which include nonperturbative type corrections. Possible scenarios generating this behavior are discussed.