Measurement of angular correlations of jets at sqrt(s)=1.96 TeV and determination of the strong coupling at high momentum transfers

TL;DR

This paper measures angular correlations of jets at the Tevatron collider to determine the strong coupling constant and test QCD predictions over a wide range of momentum transfers, providing a novel observable sensitive to QCD dynamics.

Contribution

It introduces a new jet angular correlation observable that is sensitive to QCD and the strong coupling, with minimal dependence on parton distribution functions, and uses it to measure the strong coupling at high momentum transfers.

Findings

Results agree with next-to-leading order perturbative QCD calculations.

Extracted strong coupling constant consistent with world averages.

Confirmed the running of the strong coupling over 50-400 GeV.

Abstract

We present a measurement of the average value of a new observable at hadron colliders that is sensitive to QCD dynamics and to the strong coupling constant, while being only weakly sensitive to parton distribution functions. The observable measures the angular correlations of jets and is defined as the number of neighboring jets above a given transverse momentum threshold which accompany a given jet within a given distance Delta-R in the plane of rapidity and azimuthal angle. The ensemble average over all jets in an inclusive jet sample is measured and the results are presented as a function of transverse momentum of the inclusive jets, in different regions of Delta-R and for different transverse momentum requirements for the neighboring jets. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb-1 collected with the D0 detector at the Fermilab Tevatron Collider in pp-bar collisions at sqrt(s)=1.96 The results are well described by a perturbative QCD calculation in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects. From these results, we extract the strong coupling and test the QCD predictions for its running over a range of momentum transfers of 50-400 GeV.