Measurement of the combined rapidity and $p_T$ dependence of dijet azimuthal decorrelations in $p\bar{p}$ collisions at $\sqrt{s}=1.96$TeV

We present the first combined measurement of the rapidity and transverse momentum dependence of dijet azimuthal decorrelations, based on the recently proposed quantity $R_{\mathrm{\Delta }\varphi }$. The variable $R_{\mathrm{\Delta }\varphi }$ 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 $\mathrm{\Delta }{\varphi }_{\mathrm{m}\mathrm{a}\mathrm{x}}$. The quantity $R_{\mathrm{\Delta }\varphi }$ is measured in $p\bar{p}$ collisions at $\sqrt{s}=1.96$TeV, as a function of the dijet rapidity interval, the total scalar transverse momentum, and $\Delta \phi_{\rm max}$. The measurement uses an event sample corresponding to an integrated luminosity of $0.7$fb${}^{-1}$ collected 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 $\mathrm{\Delta }{\varphi }_{\mathrm{m}\mathrm{a}\mathrm{x}}$.