Measurement of the ratio of the 3-jet to 2-jet cross sections in pp collisions at √{ s} = 7 TeV

A measurement of the ratio of the inclusive 3-jet to 2-jet cross sections as a function of the total jet transverse momentum, H_T, in the range 0.2 <H_T < 2.5 TeV is presented. The data have been collected at a proton-proton centre-of-mass energy of 7 TeV with the CMS detector at the LHC, and correspond to an integrated luminosity of 36 pb^-1. Comparisons are made between the data and the predictions of different QCD-based Monte Carlo models for multijet production. All models considered in this study are consistent with the data for H_T > 0.5 TeV. This measurement extends to an H_T range that has not been explored before.