A Quantum Diaries Survivor

Minutes after posting about the Bs meson, where I discussed the ridiculous internal rules for paper publication of the CDF collaboration, I remembered I had to post about OUR latest paper – Giorgio’s Ph.D. thesis, a top search analysis that has taken three years to complete. A new technique to extract top decays from CDF data.

The paper’s title and abstract follow:

Measurement of the top-antitop production cross section in proton-antiproton collisions at sqrt(s)=1.96 TeV using missing Et plus jets events with secondary vertex b-tagging

The CDF Collaboration

Abstract

We present a measurement of the top-antitop production cross section in proton-antiproton collisions at sqrt(s)=1.96 TeV which uses for the first time events with an inclusive signature of significant missing transverse energy and jets. The measurement is thus sensitive to leptonic W decays regardless of lepton type. Heavy flavor jets from top quark decay are identified with a secondary vertex tagging algorithm. From 311 inverse picobarns of data collected by the Collider Detector at Fermilab we measure a production cross section of 5.8+-1.2+0.9-0.7 pb for a top quark mass of 178 GeV/c2, in agreement with previous determinations and standard model predictions.

So, when I spoke about CDF’s publication process being long and boring in the last post, I had very close memories in mind… Giorgio blessed our results last July, and since then the result has been public. But it was only last Thursday that, with a Paper Seminar, the final internal act before submission to PRL was consumed.

The measurement is CDF’s third-best determination of the top production cross section by CDF, and is thus competitive with measurements exploiting the “golden” charged lepton signatures of top quark decay. Remarkably, charged leptons in this analysis are explicitly vetoed, to obtain a totally independent selection of the top signal.

I am really proud of this new methodology, which in Padova we have started to exploit for a new measurement of the top quark mass (from the same selected sample, and making large use of the same technical details used to estimate backgrounds in the cross section determination). Elena is working at that for her Master thesis. In the meantime, Marco (another student I am tutoring) is basing his Ph.D. on a demonstration of the physics capabilities of the CMS experiment at the LHC (which is still in construction – see a few posts below a discussion on that) with the same signatures: particularly, in helping isolate a signal of top-antitop production in association with a SM Higgs boson. It is this latter analysis that has been taking most of my brain’s CPU in the last few weeks. I will post something about that early next week.