This Letter reports the observation of a high transverse momentum Z→bb signal in proton-proton col-lisions at √s=8TeVand the measurement of its production cross section. The data analysed were collected in 2012 with the ATLAS detector at the LHC and correspond to an integrated luminosity of 19.5fb-1. The Z→bb decay is reconstructed from a pair of b-tagged jets, clustered with the anti-kt jet algorithm with R =0.4, that have low angular separation and form a dijet with pT > 200GeV. The signal yield is extracted from a fit to the dijet invariant mass distribution, with the dominant, multi-jet back-ground mass shape estimated by employing a fully data-driven technique that reduces the dependence of the analysis on simulation. The fiducial cross section is determined to be σfidZ→bb =2.02±0.20(stat.) ±0.25(syst.) ±0.06(lumi.) pb=2.02±0.33pb, in good agreement with next-to-leading-order theoretical predictions.
