We point out an inconsistency in perturbative QCD predictions previously used for dijet azimuthal decorrelations for azimuthal angles of $Deltaphi_{rm dijet} < 2pi/3$ between the two jets. We show how the inconsistency arises and how the calculations
can be modified to provide more accurate results that exhibit a smaller scale dependence and give a better description of the data than the inconsistent results. We also explain how the quality of the predictions strongly depends on a perceivedly minor detail in the definition of the dijet phase space and give recommendations for future measurements.
We present a comprehensive overview of theory-data comparisons for inclusive jet production. Theory predictions are derived for recent parton distribution functions and compared with jet data from different hadron-induced processes at various center-
of-mass energies sqrt(s). The comparisons are presented as a function of jet transverse momentum pT or, alternatively, of the scaling variable xT = 2pT/sqrt(s).
We present the first measurement of the inclusive three-jet differential cross section as a function of the invariant mass of the three jets with the largest transverse momenta in an event in p anti-p collisions at sqrt(s) = 1.96 TeV. The measurement
is made in different rapidity regions and for different jet transverse momentum requirements and is based on a data set corresponding to an integrated luminosity of 0.7 fb^{-1} collected with the D0 detector at the Fermilab Tevatron Collider. The results are used to test the three-jet matrix elements in perturbative QCD calculations at next-to-leading order in the strong coupling constant. The data allow discrimination between parametrizations of the parton distribution functions of the proton.
