A Quantum Diaries Survivor

The DZERO experiment is one of the two multi-purpose detectors that have collected 1.96 TeV proton-antiproton collisions at the Fermilab Tevatron collider until two years ago, when the machine was decommissioned. Experiments of this kind out-live the demise of the hardware, since the extraction of precise physics measurements from the large datasets accumulated may take several years to complete. And in fact, it is not a surprise to see two new preprints in the Arxiv (here and here) which describe in detail the experimental techniques that the collaboration uses to extract jet physics results from the data.

In 1989 the CDF experiment was sitting on its first precious bounty of proton-antiproton collisions, delivered by the Tevatron collider at the unprecedented energy of 1.8 TeV. One of the first measurements that was produced was the measurement of the mass of the Z boson, which was at the time known with scarce precision by the analysis of a handful of candidates produced by the CERN SppS collider, at a third of the Tevatron energy. 

No, this is not an article about top models. Rather, the subject of discussion are models that predict the existence of heavy partners of the top quark.

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.

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.

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.

The results of the LUX experiment are out - and they are negative: no dark matter signal has been spotted by the extra sensitive detector. This is a normal day for you and me, but a gloomy day for those that counted on the neutralino to be the first supersymmetric particle to show up and redeem decades of claims.

Do you remember the dijet bump at 140 GeV that CDF published in March 2011 ? This was a surprising excess in the mass distribution of pairs of jets found in events containing a leptonic W boson decay.

Yesterday evening I chanced to attend, invited by a friend, the opening of the 2013-2014 academic year of the university of Venice "Ca' Foscari", which was held at the Malibran theater. It was the first time I attended one such event, since technically (and practically) I am not an academic, but a researcher at the INFN, the Italian National Institute of Nuclear Physics. I do occasionally teach university courses (I just took a break from doing so after 5 years of teaching a course of subnuclear physics for 5th year undergraduates); but I do that for the university of Padova, not Venice - my office is at the department of physics of the university of Padova. Besides, Venice does not have a course of laurea in Physics.

Please note: spoiler information in this article!

The recent movie "Gravity", featuring the two hollywood stars George Clooney and Sandra Bullock, is a very interesting experiment in film-making.I can hardly recall other movies with just two characters, so this must clearly be a rare occurrence and one which shows that the movie treads in largely unexplored territory. Can people be entertained by one-man shows ? Well, yes, if the story is an extraordinary one. Tom Hanks does excellently in "Cast Away", for instance. "Gravity" is similar in the use of the loneliness of the protagonist and the large odds against her survival. But it is more radical in the total absence of other human figures, except Clooney of course.

The president Fernando Ferroni sent today an open, touching message to the personnel of the National Institute of Nuclear Physics, the Italian research organization he directs. The INFN contributed to the discovery of the Higgs boson by participating to the CMS and ATLAS experiments at CERN, providing funding and personnel -administrative staff, technicians, and researchers who are active members of the two big collaborations and who gave critical contributions to the discovery.