The following text, a short excerpt from the book "Anomaly!", recounts the time when the top quark was about to be discovered, in 1994-95. After the "evidence" paper that CDF had published in 1994, the CDF and DZERO experiments were both running for the first prize - a discovery of the last quark.
The Tevatron soon began breaking one instantaneous luminosity record after another, and good data piled up at an accelerating pace. It would only be a matter of time before one of the two experiments reached a five-standard-deviations excess in one of the top search channels and decided to finish the business, putting forth an observation claim of the new particle. The intrinsic randomness of particle collisions could play tricks, as small statistical fluctuations could decisively favour one experiment with respect to the other. For instance, a couple of extra dilepton events could tilt the balance. Note that the dilepton final state was the one where the two experiments had roughly equal sensitivity, as no secondary vertex b-tags were required in the event selection there.
In the single-lepton searches, due to the lack of a micro-vertex detector, DZERO could only tag b-quark jets “à la SLT,” by reconstructing low-momentum muons contained within hadronic jets; hence it was at a marked disadvantage versus CDF. On the other hand, while CDF had refused to use the kinematical information in W+jets events for significance calculations, DZERO could in principle decide to exploit something similar to overtake its rival. And indeed, DZERO was using two kinematical variables constructed out of jet energies to enhance the top content of their selected data. Using Run 1A data the competitors had published a slight excess of events (nine, when 3.8 were expected), as well as a spectacular dilepton candidate which had for a while brought some collaborators to caress the idea of publishing a top discovery claim based solely on that event.
In the end DZERO had only produced a 131 GeV lower limit on the top quark mass, and a 1.9-standard deviations excess; but in their paper they noted that their sensitivity to the top quark was similar to that of CDF.
So now the tension was breaking a record high across the ring, and the idea that DZERO could grab the prize of a definitive top discovery in the final rush, after the feet-on-the-ground decision of CDF to only put forth a solid, well-justified and unassailable claim of three-sigma evidence a few months before, was nothing short of a nightmare to the CDF members.
Of course, with two experiments working only a mile apart, whose members shared tables in the cafeteria of the Wilson Hall, there was a secrecy issue. CDF and DZERO members who worked at the top search were under big pressure, and lunch time was one of the few moments of their daily routine when they could exchange a relaxed word with colleagues about their work. This entailed the danger of involuntarily leaking information to the members of the competing collaboration, who might be sitting a few feet away.
The researchers were careful: it was against their interest to inform the competition on the status of the ongoing analyses. But despite the care, words spread quickly in the lab. Fermilab theorists, who often shared lunch tables with experimentalists from the two collaborations, craved for any hint about how the searches were going. They sometimes ended up acting as messengers between the two otherwise non-interacting groups, as they traded in small bits of information acquired from chats with DZERO when they asked for hints from CDF, and vice versa.
Among those most worried by the possibility of leaks was Alvin Tollestrup, the patriarch of CDF. His office was close to the one of Brenna Flaugher, who was married with Tom Diehl, a DZERO member. Crossing Brenna in the hall every day kept reminding Alvin of the impending danger. One day he could not hide his worries with her.
“Brenna, there’s one thing I would like to ask you – you know, your husband works in DZERO, and I am wondering whether you are paying enough attention to avoid giving out information on the status of our top searches...”
“Oh, we never discuss internal information among us, we have much more fun talking about the people. And besides, you can find out more at lunch tables in the cafeteria than by direct contacts with the other collaboration’s members.”
“Are you sure? I mean, you never let go any secrets about our analyses? I might imagine that during bedtime chats, for instance...”
Brenna was so surprised by Alvin’s insistence that she figured he must be kidding, so she decided to play along, by telling a lie so blatantly false that the argument would be forcefully closed.
“No, not at all. In fact, we started sleeping in different rooms as soon as this top search stuff got so intense.”
“Ah, that’s quite wise! Quite wise! Thanks, that’s reassuring.” Brenna was then not so sure that Alvin was really kidding, but she could not figure out how to explain his behavior. At least this is what she remembers, 20 years later.