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

The azimuthal correlation, Δϕ_12, of high transverse momentum jets in pp collisions at √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 Δϕ_12 is observed. In the back-to-back region of Δϕ_12→π, 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 α_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 Δϕ_12 measurements are also compared with predictions using MCatNLO together PYTHIA8, illustrating the importance of details of the parton shower evolution.

Azimuthal correlations ; high transverse momentum jets ; parton branching ; NLO

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