1203.6034 (D0 Collaboration)

Observation of a narrow mass state decaying into Upsilon(1S) + gamma in
ppbar collisions at sqrt(s) = 1.96 TeV    [PDF]

D0 Collaboration

Using data corresponding to an integrated luminosity of 1.3 fb^-1, we observe a narrow mass state decaying into Upsilon(1S)+gamma, where the Upsilon(1S) meson is detected by its decay into a pair of oppositely charged muons, and the photon is identified through its conversion into an electron-positron pair. The significance of this observation is 5.6 standard deviations. The mass of the state is centered at 10.551 \pm 0.014 (stat.) \pm 0.017 (syst.) GeV/c^2, which is consistent with that of the state recently observed by the ATLAS Collaboration.

View original: http://arxiv.org/abs/1203.6034