Studies of the underlying event in ATLAS

Particle distributions sensitive to the underlying event have been measured with the \nATLAS detector at the LHC. Charged particle multiplicity, \n charged and inclusive sum transverse momentum (pT) densities and mean \n charged-particle \pT in the regions of each event, azimuthally \n transverse to the hardest jet, are presented. \n The underlying event properties are investigated for soft minimum bias events, \n events with hard jets.\n When compared to the predictions of different Monte Carlo models, \nthe data show sensitivity to the modeling of the underlying event.