CDF Sees Evidence for Single Top August 14, 2007Posted by gordonwatts in physics.
At last Friday’s Fermilab Wine & Cheese CDF showed slides in which they crossed the magical 3 sigma threshold for observation of single top: Evidence! They have two analyses — the Matrix Element and the Likelihood Fit. The Matrix Element is at 3.1 sigma, the Likelihood is at 2.7 sigma. The main change since their last result seems to be a substantial increase in the size of their data set (1.5 fb-1).
That must have been a lot of work! Congrats!
D0 is not updating its results for this round of conferences — so we remain at 3.5 sigma.
The Matrix Element shows a steady increase in sensitivity that is understandable. But I’m curious to know what happened with the likelihood. Back at the end of 2006 it showed no sensitivity in the 1 fb-1 version of the analysis (reported an expected limit, and the observed limit was even tighter than the expected one), but now has almost 3 sigma expected sensitivity. Were they just unlucky before and lucky this time? Or did something fundamental change? Unfortunately, this talk is not the talk to describe this — Mark’s job was to present all the recent new results in 45 minutes; so no time for details!
UPDATE: It was pointed out that we are now at 3.6 sigma, not 3.5 sigma. Ops!