Recent COMPASS results on the nucleon longitudinal spin structure and QCD fits

The latest measurements of the proton longitudinal spin structure function, ɡ_1^p, in the deep inelastic (DIS) regime are presented. They improve the statistical accuracy of the existing data and extend the kinematic domain to a lower value of x and higher values of Q^2. A global NLO QCD fit of all ɡ_1 world data on the proton, deuteron and neutron has been achieved. The results give a quantification of the quark spin contribution to the nucleon spin, 0.26 = 0.113 +- 0.038 +- 0.035 is obtained at leading order at x ~ 0.1. In parallel, the double spin asymmetry in the photoproduction regime is also studied. Finally, preliminary results on quark fragmentation functions into pions extracted from a LO fit of pion multiplicities in semi-inclusive DIS are presented.