47 Chapter 2: Motivation Figure 2.11: Chew-Frautschi plot of the Regge trajectories α ( M $^{2}$) for the Λ and Σ hadrons. Poles at half-integer values of α correspond to the masses of the narrow resonances. Figure adapted from [314]. strap model, in which the hadrons themselves are exchanged to create the bind- ing strong force; in a self-consistent way the hadrons create the force which allows their existence. This model implied a duality: the poles in the s and t channels would be identical. Unlike a Feynman-like calculation, including all channels would in this case result in double counting. Then in 1968 Veneziano [315] proposed an actual formula for scattering amplitudes with all the required analytic and duality properties that also had