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.
As I mentioned a few months ago, lately I have been writing a science book for laymen. The idea is to focus on the history of CDF, a particle physics experiment that collected data from 1985 to 2011 at the Fermilab laboratory near Chicago.
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.
I received the following comment from Bo Thide', one of the authors of
the paper where Fabrizio Tamburini and collaborators explain their novel
method to multiply the transmission of information via EM waves (see here
). I think his points are of interest to many so I decided to elect his comment to a independent posting here.
By the way, Bo Thide' is a Swedish professor at the Uppsala department of Physics and Astronomy. For his CV see here
----From Bo Thide':
At 125 GeV of mass, the Higgs boson is a very heavy particle; yet its natural width is predicted to be of just 4.15 MeV in the standard model, a value much smaller than that of particles of similar mass. The top quark, for instance, has a width of 1.5 GeV; and the Z boson has a width of 2.5 GeV: three orders of magnitude larger.