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.
"This time we're shooting through a brick!"
Larry Nodulman (during a discussion on the reconstruction of electrons in the CDF II detector, just refurbished with a new set of silicon microstrip layers (SVX'), more powerful and capable of identifying the impact parameter of charged tracks with a dozen micron accuracy, but also heavier and bulkier than its predecessor, and thus providing more material for multiple scattering of particles.)
A 1.1 metric Ton satellite will re-enter the earth's atmosphere in the next 48 hours, fragmenting into smaller pieces as it falls. The exact location of the fall is unknown, so you better watch out... Or not.
I was discussing this event with my daughter this morning, and it ended up being an instructive discussion on random events of very low probability. If we are totally oblivious of the satellite orbit, and forget different likelihood of earth surface points for the re-entry (the very north and south latitude are much less likely), we can try and compute how likely it is that one of, say, 50 large fragments of the satellite will end up falling within a 100 m^2 area around us -which would be frightening enough.
These days I am trying to reconstruct some stories from my old experiment, CDF. The CDF experiment was conceived in 1979 and constructed in the early eighties at the Fermi laboratories in Batavia, near Chicago. CDF took the first proton-antiproton collisions in 1985, and it collected data in1987-88, 1992-96, and 2001-2011, thus becoming the longest-lasting particle physics experiment in the history of science.