Hagedorn Temperature - The Statistical Bootstrap Model (SBM)

The Statistical Bootstrap Model (SBM)

Hagedorn next addressed the experimental fact that resonance formation dominates the scattering cross section and proposed the Statistical Bootstrap Model (SBM). To put SBM in a nutshell one may say that each of the many resonant state into which hadrons can be excited through a collision is itself a constituent of a still heavier resonance, while being also composed of lighter ones. In this way, a matter cluster consisting of hadron resonances becomes a constituent cluster when compressed to its natural volume: fireballs going into fireballs living on fireballs forever and all in a logically very consistent way. Hagedorn obtained within the SBM approach to a strongly interacting system an exponential rising mass spectrum of resonant states. Experimental results for hadronic level counting can now be followed up to nearly 5000 cataloged resonances. They agree beautifully with theoretical SBM expectations. As our knowledge has increased, the observed mass spectrum has become a better exponential. As time has gone by, the understanding of particle production process brought about by Hagedorn has grown in significance. Hagedorn's article which introduces the statistical bootstrap model of particle production, and places the maximum temperature in the particle physics vocabulary has found a place among the most cited physics papers.