A search for excited states of the Bc(±) meson is performed using 4.9  fb(-1) of 7 TeV and 19.2  fb(-1) of 8 TeV pp collision data collected by the ATLAS experiment at the LHC. A new state is observed through its hadronic transition to the ground state, with the latter detected in the decay Bc(±)→J/ψπ(±). The state appears in the m(Bc(±)π(+)π(-))-m(Bc(±))-2m(π(±)) mass difference distribution with a significance of 5.2 standard deviations. The mass of the observed state is 6842±4±5  MeV, where the first error is statistical and the second is systematic. The mass and decay of this state are consistent with expectations for the second S-wave state of the Bc(±) meson, Bc(±)(2S).

The luminosity calibration for the ATLAS detector at the LHC during pp collisions at in 2010 and 2011 is presented. Evaluation of the luminosity scale is performed using several luminosity-sensitive detectors, and comparisons are made of the long-term stability and accuracy of this calibration applied to the pp collisions at . A luminosity uncertainty of is obtained for the 47 pb−1 of data delivered to ATLAS in 2010, and an uncertainty of is obtained for the 5.5 fb−1 delivered in 2011.

Distributions of transverse momentum and the related angular variable of Drell–Yan lepton pairs are measured in 20.3 fb of proton–proton collisions at  TeV with the ATLAS detector at the LHC. Measurements in electron-pair and muon-pair final states are corrected for detector effects and combined. Compared to previous measurements in proton–proton collisions at  TeV, these new measurements benefit from a larger data sample and improved control of systematic uncertainties. Measurements are performed in bins of lepton-pair mass above, around and below the Z-boson mass peak. The data are compared to predictions from perturbative and resummed QCD calculations. For values of the predictions from the Monte Carlo generator ResBos are generally consistent with the data within the theoretical uncertainties. However, at larger values of this is not the case. Monte Carlo generators based on the parton-shower approach are unable to describe the data over the full range of while the fixed-order prediction of Dynnlo falls below the data at high values of . ResBos and the parton-shower Monte Carlo generators provide a much better description of the evolution of the and distributions as a function of lepton-pair mass and rapidity than the basic shape of the data.