Basic processes and formalism for the hadronic production of three large-pTjets

We evaluate those processes in perturbative quantum chromodynamics which can lead to the production of three high-$p_T$ jets in hadron-hadron collisions. A formalism is proposed which incorporates event vetos to separate hard-scattering jets from spectator jets. These vetos modify the scaling violations of the initial parton distribution functions. A simple estimate indicates that the three-jet fraction in high-$p_T$ hadron processes may be up to four times larger than the corresponding three-jet fraction in $e^{+}{e}^{-}$ annihilation.