* In their original scheme Gell-Mann, Fritzsch, and Bardeen called them red, white, and blue (inspired by the French national flag). However, it soon became clear that the three primary colours would work better as, when blended, they produce the colour white. To avoid confusion I have adopted the currently accepted terminology from the outset.
* The energies of cosmic ray particles are typically between 10 MeV and 10 GeV, but very occasionally particles of incredibly high energies are recorded. On 15 October 1991 a cosmic ray particle was detected in Utah with an energy of approximately 300 million TeV. This was referred to as the ‘Oh-My-God’ particle, thought to be a proton accelerated to speeds very close to that of light.
* These were rather inaccurately reported as experiments which ‘split the atom’.
* Electromagnetic separation was not the only technique used. A huge gaseous diffusion plant (K-25) and a thermal diffusion plant were also constructed at Oak Ridge.
* This was renamed the Organisation Européenne pour la Recherche Nucléaire (European Organization for Nuclear Research) when the provisional Council was dissolved. However, the acronym OERN was judged to be clumsier than CERN, so the original acronym was retained.
* Gell-Mann was unimpressed. He called them ‘put-ons’. In truth, ‘partons’ are not just quarks – they can be both quarks and the gluons that transmit the colour force between them.
* It was named for the mother of the giant Gargantua, from French Renaissance author Francois Rabelais’ sixteenth-century novels The Life of Gargantua and Pantagruel.
* This was renamed the Fermi National Accelerator Laboratory (Fermilab) in 1974.
* The CERN physicists had also by this time found a single ‘gold-plated’ weak neutral current event among some of the older photographs from Gargamelle. This involved the interaction of a muon anti-neutrino with an electron, a much rarer process but one that is free from background contamination. It was unambiguous evidence, but it was still only one photograph. Eventually, after searching through almost one and a half million photographs, only three such events were found.
* The ratio of muon neutrinos and anti-neutrinos in the NAL experiments was of the order of two to one. The weighted average of the CERN ratios for muon neutrinos and anti-neutrinos is therefore 0.29.
* Think about your childhood experience of pushing the north poles of two bar magnets together. The resistance you feel increases as you push the magnets closer together.
* In fact, ’t Hooft had already concluded that Yang–Mills gauge theories could show this counter-intuitive behaviour, but he was busy working on renormalization at this time and did not follow it up.
† Massless gluons? What about the claims of Heisenberg and Yukawa, that the carriers of the strong force should be large, massive particles? This would indeed be a requirement if the strong force were like gravity or electromagnetism, but it’s not. The asymptotically free colour force can be quite happily carried by massless particles. Like the quarks, these are confined inside hadrons, which is why they are not as ubiquitous as photons.
* Analogies of this kind are colourful (no pun intended) but remain speculative. To this day, confinement remains a problem in QCD that has yet to be resolved.
* These quark mass data are taken from C. Amsler et al., Physics Letters B, 667 (2008), p. 1.
* If the mass of the proton is taken to be 938 MeV, then these correspond to about 88 and 100 times the proton mass, respectively.
* Martinus Veltman wrote, of Rubbia: ‘When he was Director of CERN, he changed secretaries at the rate of one every three weeks. This is less than the average survival time of a sailor on a submarine or destroyer in World War II…’ See Veltman, p. 74.
* Wilson had run into problems with the funding for Fermilab and had quit in frustration. As it turned out, after an exhaustive review of the options in November 1978, Lederman decided that the risks associated with using the existing facility as a proton–anti-proton collider were too great. He was not prepared to gamble in the way that van Hove was, and decided to throw his weight behind a renewed effort to secure funding for the Tevatron.
* More recent evaluation puts this energy somewhere in the region of two hundred thousand billion GeV.
† Although ‘grand’ and ‘unified’, GUTs do not seek to include the force of gravity. Theories that do so are often referred to as Theories of Everything, or TOEs.
* Liquid water can be supercooled to temperatures up to 40 degrees below freezing.
† These experiments involved searching for a single proton decay event from a large volume of protons shielded from cosmic rays. As Carlo Rubbia explained: ‘…just put half a dozen graduate students a couple of miles underground to watch a large pool of water for five years.’ Quoted in Woit, p. 104.
* These tiny temperature variations have since been measured in even more exquisite detail by the Wilkinson Microwave Anisotropy Probe (WMAP). Results reported in February 2003, March 2006, February 2008, and January 2010 have helped to confirm and refine the standard, so-called lambda-CDM (cold dark matter) model of the universe in which inflation plays a crucial part. According to the most recent WMAP data, the universe is 13.75±0.11 billion years old.
* Strictly speaking, this is not quite true. A class of ‘technicolour’ theories introduce new extra-strong forces which can also drive electro-weak symmetry-breaking. These theories can also account for the masses of the W and Z particles, but struggle to predict the quark masses correctly. For this reason, the Higgs mechanism is more favoured. Steven Weinberg, personal communication, 24 February 2011.
* To put this in perspective, in 2011 Britain’s contribution to the CERN budget was 15 per cent, or £109 million ($174 million), less than £2 per year for every UK citizen. ‘That’s literally peanuts,’ said ATLAS physicist and TV presenter Brian Cox, ‘In fact, we spend more here on peanuts than we do on the LHC.’ (Sunday Times, 27 February 2011).
* Aleph stands for Apparatus for LEP Physics.
† Delphi stands for Detector with Lepton, Photon, and Hadron Identification.
* Neutralinos are formed from combinations of photinos, zinos, and neutral higgsinos. See Kane, p. 158.
* There was obviously no such statistical measure for the rumour itself…
* The luminosity is a measure of the number of particles that can be squeezed into the collision point, and hence the number of potential collisions. Not all particles in the collision point will actually collide. Nevertheless, the luminosity gives the likelihood that a number of collisions will occur.
* The shutdown was judged to be necessary in order to open up some 27,000 interconnections between the main superconducting magnets, repair them, and clamp them together so that they would support the higher currents necessary to deliver 7 TeV per beam.
* This is based on recommendations for collision energies of 7 TeV reported by the LHC Higgs Cross Section Working Group. The calculated cross sections for Higgs production from gluon-gluon fusion processes vary depending on the mass of the Higgs, from about 18 picobarns at 115 GeV to around 3 picobarns at 250 GeV. The average in this Higgs mass range is about 9 picobarns.
* The leptons and neutrinos are produced in combinations. For example, a W− particle will decay into an electron or a muon and a corresponding anti-neutrino, a W+ particle will decay into a positron or anti-muon and a corresponding neutrino.
† Again, the leptons are produced in combinations: electrons with positrons, muons with anti-muons.
* The phrase ‘Raffiniert ist der Herr Gott. Aber Boshaft ist Er Nicht’ is carved in stone above the fireplace in a room in Fine Hall, Princeton University, in memory of Einstein.
* Although the particle he predicted didn’t become widely known as the Higgs boson until 1972.
† Sadly, Robert Brout died in May 2011, after a long illness. The Nobel Prize is not awarded posthumously, and each Prize can only be shared by three individuals.
* OPERA stands for Oscillation Project with Emulsion-tRac
king Apparatus and is a collaboration between CERN and the Laboratori Nazionali del Gran Sasso (LNGS).
* Kibble had other commitments that day. Higgs, Englert, Guralnik and Hagen all attended the seminar.
Higgs:The invention and discovery of the 'God Particle' Page 24
