Observation of a new χb state in radiative transitions to ϒ(1S) and ϒ(2S) at ATLAS

The bðnPÞ quarkonium states are produced in proton-proton collisions at the Large Hadron Collider at ffiffiffisp ¼ 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4:4 fb1, these states are reconstructed through their radiative decays to ð1S; 2SÞ with ! þ. In addition to the mass peaks corresponding to the decay modes bð1P; 2PÞ ! ð1SÞ, a new structure centered at a mass of 10:530 0:005ðstatÞ 0:009ðsystÞ GeV is also observed, in both the ð1SÞ and ð2SÞ decay modes. This structure is interpreted as the bð3PÞ system.