Improved luminosity determination in pp collisions at root s=7 TeV using the ATLAS detector at the LHC - Aad, G; Abajyan, T; Abbott, B; Abdallah, J; Khalek, SA; Abdelalim, A; Abdinov, O; Aben, R; Abi, B; Abolins, M; AbouZeid, O; Abramowicz, H; et al. (EUROPEAN PHYSICAL JOURNAL C, 2013)