Azimuthal correlations of high transverse momentum jets at next-to-leading order in the parton branching method

Abstract

The azimuthal correlation, $\hat{I}”\ddot{I}{•}_{12}$, of high transverse momentum jets in pp collisions at $\sqrt{s}=13$ TeV is studied by applying PB-TMD distributions to NLO calculations via MCatNLO together with the PB-TMD parton shower. A very good description of the cross section as a function of $\hat{I}”\ddot{I}{•}_{12}$ is observed. In the back-to-back region of $\hat{I}”\ddot{I}{•}_{12}\to \ddot{I}€$, a very good agreement is observed with the PB-TMD Set 2 distributions while significant deviations are obtained with the PB-TMD Set 1 distributions. Set 1 uses the evolution scale while Set 2 uses transverse momentum as an argument in $\hat{I}{\pm }_s$, and the above observation therefore confirms the importance of an appropriate soft-gluon coupling in angular ordered parton evolution. The total uncertainties of the predictions are dominated by the scale uncertainties of the matrix element, while the uncertainties coming from the PB-TMDs and the corresponding PB-TMD shower are very small. The $\hat{I}”\ddot{I}{•}_{12}$ measurements are also compared with predictions using MCatNLO together PYTHIA8, illustrating the importance of details of the parton shower evolution.

15 pages, 8 Figures