Underlying event characteristics and their dependence on jet size of charged-particle jet events in pp collisions at root(s)=7 TeV with the ATLAS detector von Aad, G, Abbott, B, Abdallah, J, Thalek, SA, Abdelalim, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, O, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, B, Adamczyk, L, Adams, D, Addy, T, Adelman, J, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, J, Aharrouche, M, Ahlen, S, Ahles, F