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

The azimuthal correlation, \(\Delta \phi_{12}\), 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 \(\Delta \phi_{12}\) is observed. In the back-to-back region of \(\Delta \phi_{12} \to \pi\), 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 \(\alpha_s\), 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 \(\Delta \phi_{12}\) measurements are also compared with predictions using MCatNLO together PYTHIA8, illustrating the importance of details of the parton shower evolution.