The spin content of the proton in quenched QCD
  We present preliminary results on the proton spin structure function at zero momentum, in the quenched approximation. Our calculation makes use of a nonperturbative means of determining the multiplicative renormalization of the topological charge density. 
B. Alles, M. Campostrini, L. Del Debbio, A. Di Giacomo, H.   Panagopoulos and E. Vicari