From Inclusive Scattering to Exclusive Reactions – recent results from HERMES

Single-spin asymmetries for semi-inclusive electroproduction of charged pions in deep-inelastic scattering of positrons are measured for the first time with transverse target polarization. They provide access to the transversity distribution via the Collins mechanism and the previously unmeasured Sivers function. The comparison of this data to similar data taken with longitudinally polarized protons provides insight into subleading-twist contributions.A second class of reaction promising new insights into the structure of the nucleon, hard exclusive electroproduction of real photons (named Deeply Virtual Compton Scattering) or mesons closely linked to the novel formalism of Generalized Parton Distributions is studied.The data were accumulated by the HERMES experiment at DESY scattering the HERA 27.6 GeV electron or positron beam off longitudinally or transversely polarized hydrogen targets.