Bootstrap model: Difference between revisions

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In [[physics]], the term '''bootstrap model''' is used for a class of theories that use very general [[consistency]] criteria to determine the form of a quantum theory from some assumptions on the spectrum of particles.

In the 1960s and '70s, the ever-growing list of [[strong interaction|strongly interacting]] particles — [[meson|mesons]]s and [[baryon|baryons]]s — made it clear to physicists that none of these particles are elementary. [[Geoffrey Chew]] and others went so far as to question the distinction between [[composite particle|composite]] and [[elementary particle|elementary particles]]s, advocating a "nuclear democracy" 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]], 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 perturbatively through field theory, but this method does not allow for particles of spin greater than 1 and without the then undiscoved phenomenon of [[confinement]], it is naively inconsistent with the observed Regge behavior of hadrons.