  Using a generalized parton model approach including spin and intrinsic parton
motion effects, and assuming the validity of factorization for large pT jet
production in hadronic collisions, we study the azimuthal distribution around
the jet axis of leading pions, produced in the jet fragmentation process. We
identify the observable leading-twist azimuthal asymmetries, which are
generated by all the physically allowed combinations of transverse momentum
dependent (TMD) parton distribution and fragmentation functions. In particular,
we show how one can isolate the Collins and Sivers contributions, and suggest a
test of the process dependence of the Sivers function by considering the effect
of color-gauge invariant initial and final state interactions.
