Top mass: 172.6 +- 1.4 GeV !! March 8, 2008Posted by dorigo in news, physics, science.
The above number is the new CDF+D0 combination of their best top mass results. The top quark is now known with a relative uncertainty of 0.8%, a value that only six years ago was thought to be unreachable by the Tevatron. And instead, through hundreds of man-years of work and ingenuity by many of the most brilliant people I know in this field, that result is now real. Such an accuracy on the top quark is a real success of the Tevatron Run II, and I am not being rethoric if I say I feel deeply proud of having been part of it, even if in a minor role.
A 0.8% precision on the top quark means a lot for the Standard Model, but the Tevatron is not done yet: I expect this number to go below 0.5% by the time the Tevatron stops running. Despite the huge (800 pb) cross section for top production at the LHC, I have my doubt that ATLAS and CMS will ever be able to do sizably better. A real legacy for the Tevatron and, let me say it, for CDF, the longest lasting physics experiment in history, ever.
I will have more to say next Monday, when I wish to discuss the result in detail, the combination, the inputs used, and the names of the real heroes behind all this. I will also have something to say about the speculations of a top mass measurement which some argued to depend on the number of jets contained in the final state… Check back here in a couple of days. Hell, this is a weekend after all!