(en) Four point amplitudes in open strings and superstrings are shown to factor in an infinite number of ways as Euler products of p-adic amplitudes. All these “adelic” formulae follow from the functional equation for Dirichlet L-functions.
Ruelle, P., Thiran, E., Verstegen, D., & Weyers, J. (1989). Adelic string and superstring amplitudes. Modern Physics Letters A, A4, 1745. https://doi.org/10.1142/S0217732389001970 (Original work published 1989)