Quantitative study of the violation of kt-factorization in   hadroproduction of quarks at collider energies
  We demonstrate the violation of kT-factorization for quark production in high energy hadronic collisions. This violation is quantified in the Color Glass Condensate framework and studied as a function of the quark mass, the quark transverse momentum, and the saturation scale Qsat, which is a measure of large parton densities. At x values where parton densities are large but leading twist shadowing effects are still small, violations of kT-factorization can be significant - especially for lighter quarks. At very small x, where leading twist shadowing is large, we show that violations of kT-factorization are relatively weaker. 
Hirotsugu Fujii, Francois Gelis, Raju Venugopalan