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 ΔR 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 ΔR 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¯ collisions at s=1.96 TeV. 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.
Highlights
10LPC, Universite Blaise Pascal, CNRS/IN2P3, Clermont, France 11LPSC, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, Grenoble, France 12CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille, France
We present a measurement of the average value of a new observable at hadron colliders that is sensitive to Quantum chromodynamics (QCD) dynamics and to the strong coupling constant, while being only weakly sensitive to parton distribution functions
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 ∆R and for different transverse momentum requirements for the neighboring jets
Summary
1.96 TeV and determination of the strong coupling at high momentum transfers arXiv:1207.4957v2 [hep-ex] 3 Dec 2012. The αs results from inclusive jet cross section data at high momentum transfers can not be regarded as tests of the RGE, since they are obtained assuming its validity. The theory predictions for R∆R which are compared to the data, and which are later used to extract αs, are given by the product of the NLO pQCD results and correction factors for non-perturbative effects, including hadronization and underlying event. This might be caused by limitations of either the perturbative calculation or the modeling of the non-perturbative effects at low pnTbmrin These R∆R results are used to determine αs and to test the two-loop RGE prediction for its running as a TABLE I: The αs(MZ) results with their absolute uncertainties and the χ2 values from the fits to the R∆R data in each of the 12 kinematic regions, defined by the pnTbmrin and ∆R requirements.
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