Below is a clip from a chapter of my book where I describe the story of the silicon microvertex detector of the CDF experiment. CDF collected proton-antiproton collisions from the Tevatron collider in 1985, 1987-88, 1992-96, and 2001-2011. Run 1A occurred in 1992, and it featured for the first time in a hadron collider a silicon strip detector, the SVX. The SVX would prove crucial for the discovery of the top quark.

Yesterday I was in Rome, at a workshop organized by the Italian National Institute for Nuclear Physics (INFN), titled "What Next". The event was meant to discuss the plan for basic research in fundamental physics and astrophysics beyond the next decade or so, given the input we have and the input we might collect in the next few years at accelerators and other facilities.

If I look back at the first times I discussed the important graph of the top quark versus W boson mass, nine years ago, I am amazed at observing how much progress we have made since then. The top quark mass in 2005 was known with 2-3 GeV precision, the W boson mass with 35 MeV precision, and we did not know where the Higgs boson was, or if there was one.

The mass of the top quark is a very important parameter of the standard model: using its value together with other no less fundamental ones (the W boson mass, the Higgs mass, and many parameters describing the properties of Z bosons) it is possible to study in great detail the predictions of the theory. In particular, due to the way heavy particles influence the Higgs field, one may verify the consistence of the standard model by looking at a graph where the top quark mass is in the x axis and the W boson on the y axis: different hypotheses for the Higgs boson mass then lie on different parallel curves. One example of such a graph is shown below. It is too complex to discuss it in detail here, but if you are curious I can supply more information in the comments thread.

Now that we know that the Higgs boson has a mass of 125 GeV and displays all the properties that a regular standard model Higgs boson should have, one question you could ask is, is it possible that a top quark decays into a Higgs boson ?

The question is a legitimate one since the top quark has a mass 40% larger than the Higgs, so in principle a decay could be allowed. For instance, one could imagine that the top "fluctuates" into a bottom quark - W boson combination, then that the W boson emits a Higgs particle, and finally the bottom quark and W boson fuse themselves into a charm quark. Or, once the top fluctuates into a Wb pair, it is the bottom quark which emits the Higgs boson before rejoining with the W creating a charm quark. The diagrams are shown below.