Bootstrap model: Difference between revisions

Revision as of 18:21, 11 April 2008

Revision as of 19:05, 18 September 2008

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Chew and followers believed that it would be possible to use crossing symmetry and [[Regge theory|Regge behavior]] to formulate a consistent S-matrix for infinitely many particle types. The Regge hypothesis would determine the spectrum, crossing and analyticity would determine the scattering amplitude--- the forces, while unitarity would determine the self-consistent quantum corrections in a way analogous to including loops. The only fully successful implementation of the program required another assumption to organize the mathematics of unitarity--- the narrow resonance approximation. This meant that all the hadrons were stable particles in the first approximation, so that scattering and decays could be thought of as a perturbation. This allowed a bootstrap model with infinitely many particle types to be constructed like a field theory--- the lowest order scattering amplitude should show Regge behavior and unitarity would determine the loop corrections order by order. This is how [[Gabriele Veneziano]] and many others, constructed [[string theory]], which remains the only theory constructed from general consistency conditions and mild assumptions on the spectrum.

Many in the bootstrap community believed that field theory, which was plagued by problems of definition, was fundamentally inconsistent at high energies. Some believed that there is only one consistent theory which requires infinitely many particle species and whose form can be found by consistency alone. This is nowadays known not to be true, since there are many theories which are nonperturbatively consistent, each with their own S-matrix. Without the narrow-resonance approximation, the bootstrap program did not have a clear expansion parameter, and the consistency equations were often complicated and unweildyunwieldy, so that the method had limited success. It fell out of favor with the rise of [[quantum chromodynamics]], which described mesons and baryons in terms of elementary particles called [[quarks]] and [[gluons]].

More generally, "bootstrapping" refers to any method of reaching higher understanding by building on lower foundations. The name derives from the fictional [[Baron Munchausen]], one of whose many tall tailstales involved lifting himself off the ground by pulling on the laces of his own boots.

== References ==