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

Abstract

<jats:title>Abstract</jats:title><jats:p>The azimuthal correlation, <jats:inline-formula><jats:alternatives><jats:tex-math>$$\Delta \phi _{12}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>Δ</mml:mi> <mml:msub> <mml:mi>ϕ</mml:mi> <mml:mn>12</mml:mn> </mml:msub> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula>, of high transverse momentum jets in pp collisions at <jats:inline-formula><jats:alternatives><jats:tex-math>$$\sqrt{s}=13$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> 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 <jats:inline-formula><jats:alternatives><jats:tex-math>$$\Delta \phi _{12}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>Δ</mml:mi> <mml:msub> <mml:mi>ϕ</mml:mi> <mml:mn>12</mml:mn> </mml:msub> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> is observed. In the back-to-back region of <jats:inline-formula><jats:alternatives><jats:tex-math>$${\Delta \phi _{12}}\rightarrow \pi $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mrow> <mml:mi>Δ</mml:mi> <mml:msub> <mml:mi>ϕ</mml:mi> <mml:mn>12</mml:mn> </mml:msub> </mml:mrow> <mml:mo>→</mml:mo> <mml:mi>π</mml:mi> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula>, 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 <jats:inline-formula><jats:alternatives><jats:tex-math>$$\alpha _\mathrm {s}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>α</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math></jats:alternatives></jats:inline-formula>, 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 <jats:inline-formula><jats:alternatives><jats:tex-math>$$\Delta \phi _{12}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>Δ</mml:mi> <mml:msub> <mml:mi>ϕ</mml:mi> <mml:mn>12</mml:mn> </mml:msub> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> measurements are also compared with predictions using MCatNLO together <jats:sc>Pythia</jats:sc>8, illustrating the importance of details of the parton shower evolution.</jats:p>