Off-shell amplitudes and 4-jet production in kT -factorization

We compute tree level QCD scattering amplitudes in the kT-factorization approach, which implies that incoming partons are off the mass-shell. To do that, we use a generalisation of the Britto-Cachazo-Feng-Witten (BCFW) recursion relation, which works, in principle, for any number of legs; we then use these results to perform a study of both Single (SPS) and Double Parton Scattering contributions (DPS) to the inclusive 4-jet production in the kT-factorization framework at leading order and center of mass energies p s = 7 TeV and 13 TeV. We discuss the importance of double parton scattering for relatively soft cuts on the jet transverse momenta and find out that symmetric cuts do not suit well the kT-factorization predictions, because of a kinematic effect suppressing the double parton scattering contribution. We thus propose the systematic use of asymmetric cuts in future experimental analyses and propose new variables to pin down DPS via the analysis of the corresponding differential distributions. QCD Evolution.