Wuppertal 2015 – scientific programme
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T: Fachverband Teilchenphysik
T 59: QCD: Vorwärtsjet, W+jet, Z+jet
T 59.3: Talk
Tuesday, March 10, 2015, 17:15–17:30, K.11.10 (K8)
Tests of αs running from QCD fits to collider data — •Oleg Kuprash1,2 and Achim Geiser1,2 — 1Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany — 2Hamburg University, Institute of Experimental Physics, Hamburg, Germany
The running of the strong coupling constant, αs(µ), is tested in a QCD analysis using jet measurements at LHC, Tevatron and HERA in combination with inclusive DIS data. Here µ is associated with the energy scale in the process, typically with the jet transverse energy. For the αs running test, the parameter nf of the running, which gives the number of active quarks contributing to loop corrections of the jet and DIS cross sections, is replaced by nf + Δ nf at energy scales greater than µ > µthresh. A series of simultaneous αs(MZ) + Δ nf + proton PDF fits to world collider cross section data is done at Next-to-Leading Order QCD, for µthresh values ranging from 1 GeV to 1 TeV. The fitted Δ nf is consistent with zero at all tested scales, which gives a precise quantitative confirmation of the QCD running of αs over 3 orders of magnitude in energy scale. The presented study also provides a new way for indirect searches of the physics beyond the Standard Model.