1112.5154 (ATLAS Collaboration)

Observation of a new chi_b state in radiative transitions to Upsilon(1S)
and Upsilon(2S) at ATLAS    [PDF]

ATLAS Collaboration

The chi_b(nP) quarkonium states are produced in proton-proton collisions at
the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS
detector. Using a data sample corresponding to an integrated luminosity of 4.4
fb^-1, these states are reconstructed through their radiative decays to
Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks
corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new
structure centered at a mass of 10.539+/-0.004 (stat.)+/-0.008 (syst.) GeV is
also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes.
This is interpreted as the chi_b(3P) system.

View original: http://arxiv.org/abs/1112.5154