Spin physics and more with HERMES
II. Physikalisches Institut, Universität Giessen, 35392, Giessen, Germany
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A review of recent results obtained by the HERMES experiment is given. Inclusive measurements on polarized and unpolarized targets provide precise information on the polarized structure functions g 1 d and g 1 p and the isoscalar unpolarized structure function ratio F 2 A /F 2 d . The geometrical acceptance of the HERMES detector and the good particle identification capabilities allow the study of semi-inclusive reactions as well. Using polarized targets, the polarized quark distribution functions $\Delta q$ can be extracted as well as a first indication of the transversity distributions $\delta q$. On unpolarized heavy targets, hadron formation in a nuclear environment is studied. Finally, data on Deeply Virtual Compton Scattering, the hard exclusive electroproduction of real photons, are presented, which are closely linked to the novel framework of Generalised Parton Distributions. For this reaction HERMES has measured the asymmetry main beam charge as well as in-beam spin.
© Società Italiana di Fisica and Springer-Verlag, 2003