Reggeons
Reggeons are theoretical particles or more precisely, trajectories of particles, that arise in the context of Regge theory. This theory was developed in the early 1960s by Tullio Regge to describe the scattering of hadrons, which are composite particles made of quarks, such as protons and neutrons. Instead of treating individual hadrons as fundamental entities, Regge theory views them as excitations on these Reggeon trajectories.
Reggeon trajectories are characterized by their spin and their mass. In Regge theory, the scattering amplitude
The concept of Reggeons has been crucial in understanding the behavior of strong interactions at high energies.