Just shy of 6 months after the presentation of the discovery of the bottomonium ground state, BaBar has presented confirmation of the discovery using Y(2S) decays to the ground state instead of Y(3S) decays. The results were presented by on of the core analysts, Peter Kim, at the QWG workshop in Nara, Japan. His slides are available online [1].
The compatibility of the results is excellent, with variations only at the level of a single statistical deviation. You can see a comparison of the (non-peaking) background-subtracted data and the overlays of the fitted peaking backgrounds (left two peaks) and the signal (right-hand peak). The previous result was a 10-sigma result; the current one is just over 3 sigma, enough for a clear confirmation but not, by itself, an independent discovery. That’s OK – we were going for confirmation, so this worked out as well as we could have hoped!
Every analysis on BaBar is led by a core team of researchers, but reflects the hard work of dozens of people in guiding and reviewing the result. As with the original bottomonium ground state work, I continue to find it remarkable what discoveries lay in this Upsilon data, and how the hard work of the BaBar collaboration continues to pay off.
A paper will soon follow.
[1] http://www-conf.kek.jp/qwg08/session1_1/kim.pdf
