Last Tuesday I was in Mantova, a pleasant little town in northern Italy, rich of monuments and treasures like the Palazzo Ducale, which hosts a vast collection of paintings and frescoes from reinassance artists. But I was not there for a private visit; I was in fact invited to comment and provide answers to questions that the audience of a movie, "The Hunt for the Higgs", were invited to ask after seeing it.
The host of the event was the "Cinema del Carbone", a small movie theater near the center of the town. The organizers called me there because they knew me from my previous participation to last years' Festivaletteratura, a literature festival which takes place yearly in September, where authors of books and other media get in touch with their public.
"We haven't the foggiest idea what drives the new high-temperature
superconductors, or what makes a snowflake, or how the mind or the
economy works. What is more, nothing high energy physics can do will ever be of the slightest direct help in solving these overwhelmingly hard problems"
Philip Anderson, The Case Against the SSC, 1987(Anderson was one of the theorists who are credited for discovering the "Higgs mechanism" in the early 1960s. He is a 1977 Nobel laureate in Physics for his studies of the electron structure of magnetic systems)
It has taken 19.5 years to Italy to sanate a wound to its democratic fabric, one which made the country look like a sort of Banana republic, where a tycoon could acquire consensus through his mediatic power, rule unchallenged, and break the law without punishment. But finally we got around it yesterday afternoon, where a vote of the Senate of Republic has decreed that Silvio Berlusconi is unfit to hold a seat in the Parliament.
The top quark is the most massive elementary particle that we have so far discovered at particle accelerators. One usually describes this by saying that the top mass is about 185 times larger than the mass of a whole proton; but since the proton is a composite object, it is not the best comparison stone; I would prefer to compare the top mass to the mass of the lightest quark, which we only roughly know to be in the range of a 2 to 5 MeV. Then one gets a more dramatic picture: the up quark and the top quark are both elementary particles, but the latter is 50,000 times larger than the former. Can that be true ?
In
a paper appeared a few days ago on the Cornell Arxiv Campbell, Ellis and Williams discuss how the LHC experiments have a chance to obtain information on the Higgs boson width by studying four-lepton events at masses much above the 126 GeV region where they cluster when produced by Higgs boson decays. Here I am going to show the graph that is at the source of this idea, and the general conclusions that the theorists reach on the precision that ATLAS and CMS can obtain on that parameter.
First of all let me explain to outsiders what is the Higgs boson width. In order to do so I need to make a short digression.
It happens in 1995, toward the end of Run 1B of the Fermilab Tevatron, in the middle of a otherwise anonymous store. The CDF detector is taking good data, and the shift crew in the control room take care of the usual business - a look at the colourful monitors that plaster the walls, a check at trigger rates, the logging of a few standard warnings issued by the data acquisition system, and the occasional browsing of e-mails.
Letter To A Demanding PhD Supervisor
Letter To A Future AGI
Living At The Polar Circle
