A search for excited states of the B±<inf>c</inf> 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 B±<inf>c</inf> → J/ψπ±. The state appears in the m(B±<inf>c</inf>π+π-) - m(B±<inf>c</inf>) - 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 B±<inf>c</inf> meson, B±<inf>c</inf>(2S). © 2014 CERN, for the ATLAS Collaboration.
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