  Invariant mass distributions of jet pairs (dijets) produced in LHC
proton-proton collisions at a centre-of-mass energy sqrt(s)=7 TeV have been
studied using a data set corresponding to an integrated luminosity of 1.0 fb^-1
recorded in 2011 by ATLAS. Dijet masses up to ~4 TeV are observed in the data,
and no evidence of resonance production over background is found. Limits are
set at 95% CL for several new physics hypotheses: excited quarks are excluded
for masses below 2.99 TeV, axigluons are excluded for masses below 3.32 TeV,
and colour octet scalar resonances are excluded for masses below 1.92 TeV.
