Where Do You Go When You’ve Made it to the Top?

What a difference a year can W make—especially when almost a thousand physicists spend that year in single‐minded pursuit of a goal. The goal in this case was the discovery of the top quark, which one year ago sat at the threshold of statistical respectability. (See PHYSICS TODAY, June 1994, page 17.) Since then, the Collider Detector Facility group and the DO group at Fermilab’s Tevatron have steadily improved their statistics and their analyses until the question of whether they have in fact seen the top quark is no longer a subject of controversy. CDF sees 56 top candidates over a predicted background of 23.1, for a statistical significance of 4.8 standard deviations. DO sees 17 events over a predicted background of 3.8, for a statistical significance of 4.6 standard deviations. Perhaps equally significant, all subsequent analyses of the kinematic, production and decay properties of the top samples are consistent between the two experiments and support the hypothesis that the excess events over background are indeed due to top production. The focus of debate now seems to have passed from whether the top has been discovered to how significant the discovery will be for particle physics. On the subject of significance, there seem to be two main camps.