Eur. Phys. J. A (2003) 18: 401-404
https://doi.org/10.1140/epja/i2002-10244-0Helicity dependence of the
https://doi.org/10.1140/epja/i2002-10244-0
Helicity dependence of the 
interaction and the GDH sum rule
INFN-Sezione di Pavia, via Bassi 6, Pavia, Italy
* e-mail: pedroni@pv.infn.it
First measurements of pion photoproduction using circularly polarized photons on longitudinally polarized protons were carried out at MAMI (Mainz) in the energy range 
-800 MeV. Results of the helicity dependence of the total inclusive photoabsorption cross-section and of the pion photoproduction channels will be presented. These data provide new input for multipole analyses and determine the main contribution to the Gerasimov-Drell-Hearn integral and the forward spin polarizability 
.
© Società Italiana di Fisica and Springer-Verlag, 2003
