QCD vacuum topological susceptibility in a non-local chiral quark model
  The topological susceptibility of QCD vacuum is studied in the framework of a covariant chiral quark model with non-local quark-quark interaction. The relation of the first moment of topological susceptibility \chi'(0) and the 'spin crisis' problem is briefly discussed. It is shown, in particular, that one always gets the inequality \chi'(0)>\chi'_{OZI}. 
A.E. Dorokhov