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Data from ATLAS are the black dots that follow a relatively smooth curve. Excited quarks would appear as bumps that are illustrated by the three coloured curves. (Courtesy: PRL)
By Hamish Johnston
Unlike most people, particle physicists can get very excited about seeing absolutely nothing.
Indeed, one of the world’s most prestigious journals has published a letter from the ATLAS collaboration at the Large Hadron Collider (LHC) about how the multibillion-euro facility has found no evidence for an “excited quark” or any other unexpected particles.
And furthermore, it’s done a much better job at not finding an excited quark than its less energetic competitor, Tevatron at Fermilab in the US.
In the Standard Model of particle physics, quarks are fundamental particles. This means that they have no internal structure and therefore no excited states. By failing to find excited quarks (or other surprise particles) at masses up to 1.26 TeV, the ATLAS team have provided invaluable guidance to physicists who are developing theories beyond the Standard Model.
Tevatron had previously excluded excited quarks to about 0.87 TeV, which required 3500 times more data than the ATLAS measurement. This performance bodes well, and we can look forward to the LHC not finding many more particles – and who knows, it might even manage to find a new particle or two.
But what’s really incredible about this paper in Physical Review Letters is the author list, which begins with G Aad and ends with V Zutshi. Normally, letters are restricted to four pages, but this one stretches to 19 pages to include all the authors and their organizations. I gave up counting authors (I think there are about 3000), but there are 177 organizations listed.
Sadly, 19 authors passed away before seeing ATLAS’s first publication of results in PRL.
The letter is published at Phys. Rev. Lett. 105 161801.
You were close. According to my R script, there were
Total authors: 3173
There will be more than a little stir when they can’t find the Higgs.
Then some really interesting alternatives will emerge.
After experimenting with my home-made ELHC (Even Larger Hadron Collider), it appeared to me that it might be a fundamental error to infer from the fact that, after the forced out head-on collision of two stable nucleons, some ephemeral quarks appear in the cloud chamber, that a nucleon is de facto constituted by the very same sub-particles. It might be just as much of a fundamental error as if it would be held that all radioactive elements with alpha-active decays contain helium, electrons, positrons, neutrinos, mesons, bosons, gamma-rays and what have you in their nuclei as standard constituents, all to be released as such at the occasion of a natural reaction. It is much more likely that the products of a forceful destruction would originate out of the energy liberated at the instant of the process and serve only for the spatial disposal of the concentrated energy involved, dissolving consequently into e-m radiation.