top quark

The top quark is the heaviest known elementary particle, as small as an electron but 340,000 times more massive! We don’t know how small those particles are, only that they are smaller than 1/1000th the size of a proton which itself is 1/100,000th the size of the smallest atom, hydrogen. Millionths, billionths, … soon we’re talking small numbers!

Twenty-five years ago, scientists on the CDF and DZero particle physics experiments at Fermilab announced one of history’s biggest breakthroughs in particle physics: the discovery of the long-sought top quark. The collaborations on the two experiments jointly made the announcement on March 2, 1995, to much fanfare. We take a look back on this day in Fermilab history a quarter-century ago.

From CERN, Oct. 7, 2019: The CMS collaboration has measured for the first time the variation, or “running,” of the top quark mass. The theory of quantum chromodynamics predicts this energy-scale variation for the masses of all quarks and for the strong force acting between them. Observing the running masses of quarks can therefore provide a way of testing quantum chromodynamics and the Standard Model.