Measurement of the combined rapidity and pT dependence of dijet azimuthal decorrelations in pp collisions at √s =1.96 TeV

FNAL-D0. We present the first combined measurement of the rapidity and transverse momentum dependence of dijet azimuthal decorrelations, based on the recently proposed quantity RΔϕ. The variable RΔϕ measures the fraction of the inclusive dijet events in which the azimuthal separation of the two jets with the highest transverse momenta is less than a specified value for the parameter Δϕmax. The quantity RΔϕ is measured in pp collisions at √s =1.96 TeV, as a function of the dijet rapidity interval, the total scalar transverse momentum, and Δϕmax. The measurement uses an event sample corresponding to an integrated luminosity of
0.7fb−1collected with the D0 detector at the Fermilab Tevatron Collider. The results are compared to predictions of a perturbative QCD calculation at next-to-leading order in the strong coupling with corrections for non-perturbative effects. The theory predictions describe the data, except in the kinematic region of large dijet rapidity intervals and large Δϕmax.