Dr Claus Buszello (Uppsala University)
We present the observation of a narrow mass state decaying into Y(1s)+photon, where the Y(1s) 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 deviation. The mass of the state is centered at 10.551+/-0.014(stat)+/-0.017 GeV, which is consistent with that of the state recently observed by the ATLAS Collaboration. We also present an update of the search for the decay B0s-->mu+mu- using the full D0 data sample of about 10.4 fb-1 of integrated luminosity. In this analysis, backgrounds have been significantly reduced compared to earlier D0 measurements by addition isolation variables, by reconstructing additional vertices near the B0s decay vertex and by employing multivariate techniques to discriminate between signal and background.