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

Abstract

The azimuthal correlation, $$\Delta \phi _{12}$$ Δ ϕ 12 , of high transverse momentum jets in pp collisions at $$\sqrt{s}=13$$ 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 $$\Delta \phi _{12}$$ Δ ϕ 12 is observed. In the back-to-back region of $${\Delta \phi _{12}}\rightarrow \pi $$ Δ ϕ 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 $$\alpha _\mathrm {s}$$ 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 $$\Delta \phi _{12}$$ Δ ϕ 12 measurements are also compared with predictions using MCatNLO together Pythia8, illustrating the importance of details of the parton shower evolution.

NLO Analysis of Small $k_T$ Region in Drell-Yan Production with Parton Branching

“…We compare these measurements with predictions from MCatNLO+CAS3, utilizing PB-sets. Notably, as previously observed in various studies [6,[11][12][13], PB-set1 tends to overestimate contributions at low transverse momenta ( T (ℓℓ)), while PB-set2 aligns well with the measurements…”

Azimuthal decorrelation for photon induced dijet production in ultra-peripheral collisions of heavy ions

“…Starting with the pioneering papers [50,51], all-order resummation of azimuthal decorrelation for QCD jets has been performed in various processes [52][53][54][55][56][57][58][59][60][61][62][63][64]. Usually, fixed-order calculations in pQCD can be used to systematically improve the description of hadronic radiation.…”

“…Before introducing our methodology, we first briefly describe two methods on the market used to perform resummation of large logarithms of the azimuthal angle for jets [50][51][52][53][54][55][56][57][58][59][60][61][62][63][64]. The first method is deriving an all-order resummation formula for the transverse momentum imbalance q T , and then constructing the azimuthal decorrelation ∆φ distribution from the q T distribution, which can be named as the "indirect method".…”

On the normalization of unintegrated parton densities

“…Recently, the authors of Ref. [29] showed that the azimuthal correlation between two jets is sensitive to the k t distribution.…”