We consider four scalar mesons scattering in large-Nc QCD. Using the worldline formalism we show that the scattering amplitude can be written as a formal sum over Wilson loops. The AdS/CFT correspondence maps this sum into a sum over string worldsheets in a confining background. We then argue that for well separated mesons the sum is dominated by flat space configurations. Under additional assumptions about the dual string path integral we obtain the Veneziano amplitude.
Armoni, A. (2016). Large-N QCD and the Veneziano amplitude. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 756, 328–331. https://doi.org/10.1016/j.physletb.2016.03.045