We show that the difference cross sections in unpolarized SIDIS e+N\to e+h+X and pp hadron production p+p\to h+X determine independently in a model independent way, in any order in QCD, the two FFs: D_u^{ h-\bar h} and D_d^{ h-\bar h}, h=\pi^\pm, K^\pm or a sum over charged hadrons. If both K^\pm and K_s^0 are measured, then e+e-\toK+X, e+N\to e+K+X and p+p\to K+X present independent measurements of just one FF: D_{ u-d}^{ K^++K^-}. The above results allow to test the existing parametrizations, obtained with various different assumptions about the FFs, and to test the $Q^2$ evolution and factorization.
Categories: hep-ph