Bootstrap model: Difference between revisions

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==Overview<!--'Nuclear democracy' redirects here-->==

In the 1960s and '70s, the ever-growing list of [[strong interaction|strongly interacting]] particles &mdash; [[meson]]s and [[baryon]]s &mdash; made it clear to physicists that none of these particles isare elementary. [[Geoffrey Chew]] and others went so far as to question the distinction between [[Composite particle|composite]] and [[elementary particle]]s, advocating a "'''nuclear democracy'''"<!--boldface per WP:R#PLA--> in which the idea that some particles were more elementary than others was discarded. Instead, they sought to derive as much information as possible about the strong interaction from plausible assumptions about the [[S-matrix]], which describes what happens when particles of any sort collide, an approach advocated by [[Werner Heisenberg]] two decades earlier.

The reason the program had any hope of success was because of [[Crossing (physics)|crossing]], the principle that the forces between particles are determined by particle exchange. Once the spectrum of particles is known, the force law is known, and this means that the spectrum is constrained to bound states which form through the action of these forces. The simplest way to solve the consistency condition is to postulate a few elementary particles of spin less than or equal to one, and construct the scattering [[Perturbation theory (quantum mechanics)|perturbatively]] through [[Quantum field theory|field theory]], but this method does not allow for composite particles of spin greater than 1 and without the then undiscovered phenomenon of [[Color confinement|confinement]], it is naively inconsistent with the observed Regge behavior of [[hadron]]s.

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''[[Bootstrapping]]'' here refers to 'pulling oneself up by one's bootstraps,' as particles were surmised to be held together by forces consisting of exchanges of the particles themselves.

In 2017 ''[[Quanta Magazine]]'' published an article in which ''bootstrap'' was said to enable new discoveries in the field of quantum theories. Decades after bootstrap seemed to be forgotten, physicists have discovered novel "bootstrap techniques" that appear to solve many problems. The bootstrap approach is said to be "a powerful tool for understanding more symmetric , perfect theories that, according to experts, serve as 'signposts' or 'building blocks' in the space of all possible quantum field theories".<ref>{{Cite web |last=Wolchover |first=Natalie |date=23 February 2017 |title=Physicists Uncover Geometric 'Theory Space' |url=https://www.quantamagazine.org/using-the-bootstrap-physicists-uncover-geometry-of-theory-space-20170223/ |work=Quanta magazine |access-date=1 October 2021 }}</ref>

==See also==