Khachatryan, V.Işıldak, Bora2016-08-042016-08-042015-05http://hdl.handle.net/10679/4383https://doi.org/10.1140/epjc/s10052-015-3376-yThis paper presents a measurement of the inclusive 3-jet production differential cross section at a proton–proton centre-of-mass energy of 7 TeV using data corresponding to an integrated luminosity of 5 fb−1fb−1 collected with the CMS detector. The analysis is based on the three jets with the highest transverse momenta. The cross section is measured as a function of the invariant mass of the three jets in a range of 445–3270 GeV and in two bins of the maximum rapidity of the jets up to a value of 2. A comparison between the measurement and the prediction from perturbative QCD at next-to-leading order is performed. Within uncertainties, data and theory are in agreement. The sensitivity of the observable to the strong coupling constant αSαS is studied. A fit to all data points with 3-jet masses larger than 664 GeV gives a value of the strong coupling constant of αS(MZ)=0.1171±0.0013(exp)+0.0073−0.0047(theo)αS(MZ)=0.1171±0.0013(exp)−0.0047+0.0073(theo) .engrestrictedAccessarticle00035567330000510.1140/epjc/s10052-015-3376-yCMSPhysicsQCDJets3-jet massPDFStrong coupling constantAlpha-S