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CMS-QCD-11-003 ; CERN-PH-EP-2013-057
Measurement of the ratio of the inclusive 3-jet cross section to the inclusive 2-jet cross section in pp collisions at $\sqrt{s}$ = 7 TeV and first determination of the strong coupling constant in the TeV range
CMS Collaboration
28 April 2013
Eur. Phys. J. C 73 (2013) 2604
Abstract: A measurement is presented of the ratio of the inclusive 3-jet cross section to the inclusive 2-jet cross section as a function of the average transverse momentum, , of the two leading jets in the event. The data sample was collected during 2011 at a proton-proton centre-of-mass energy of 7 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 5.0 inverse femtobarns. The strong coupling constant at the scale of the Z boson mass is determined to be alphaS[MZ] = 0.1148 +/- 0.0014 (exp.) +/- 0.0018(PDF) +0.0050/-0.0000 (scale), by comparing the ratio in the range 0.42 < < 1.39 TeV to the predictions of perturbative QCD at next-to-leading order. This is the first determination of alphaS[MZ] from measurements at momentum scales beyond 0.6 TeV. The predicted ratio depends only indirectly on the evolution of the parton distribution functions of the proton such that this measurement also serves as a test of the evolution of the strong coupling constant beyond 0.42 TeV. No deviation from the expected behaviour is observed.
Links: e-print arXiv:1304.7498 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; Public twiki page ; HepData record ; CADI line (restricted) ;
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Compact Muon Solenoid
LHC, CERN