Determination of the strong coupling constant from multi-jet production with the ATLAS detector

The strong coupling constant alpha_S is measured in proton-proton collisions at a centre-of-mass energy of 7 TeV using 38 pb^−1 of data recorded by the ATLAS detector. An inclusive jet production ratio distribution is used to reduce parton distribution functions dependence and measure the coupling strength at energy scales between 100 GeV and 1.5 TeV. The value of the strong coupling constant alpha_S(MZ) is measured to be 0.111^+0.016_−0.012, in agreement with similar measurements performed at hadron colliders and the world average value. Results are also consistent with the running of the coupling as predicted by Quantum Chromodynamics, tested for the first time at energy scales greater than 209 GeV.