Saturday, October 27, 2012

Preons are dead, but prequarks are fully alive

In an article at ( ), it wrote, “The latest Scientific American has a cover story about particle physics … . It’s called “The Inner Life of Quarks” and discusses models in which quarks and other elementary particles of the standard model are composites of more elementary objects called “preons”. The fact that the papers on the subject it refers to are from 1979 should make one suspicious: an idea that hasn’t had major developments in 33 years is a dead idea. Besides the overwhelming experimental evidence against preons (with the LHC bringing in many new much stronger negative results), the idea has huge inherent problems. The main issue is that one is trying to put together composites with masses as small as MeVs (or lower, if you try to do this with neutrinos) while the data says that things are point-like up to TeV scales, with just the forces you know about up to such scales.

The following is the summary of Scientific American’s article.
1.       In 1869 Dmitri Mendeleev created the periodic table of chemical elements by noticing that elements' properties fit into a repeating pattern, which physicists later explained as a consequence of atomic structure. A similar story may be playing out in particle physics again today.

2.       The 12 known elementary particles have their own repeating patterns, suggesting they are not truly fundamental but actually tiny balls containing smaller particles, which physicists tentatively call preons.

3.       Other evidence argues against this possibility. The Large Hadron Collider at CERN, along with several lesser-known experiments, may finally settle the question.

There are major differences between the preons and the prequarks. The details are available at .