Feasibility of measuring nonanalytic QED coupling from pair creation in strong fields

In the quasistatic regimes of nonlinear Breit-Wheeler and trident pair creation, the rates can exhibit a nonanalytic dependency on the fundamental coupling of quantum electrodynamics, in a form similar to Schwinger vacuum pair creation. To reach this tunneling regime requires satisfying competing requirements: a high-intensity but low quantum strong-field parameter with sufficient pair creation to be observed. Using a locally monochromatic approach, we identify the parameter regime where tunneling pair creation could be measured in experiment. Studying several scenarios of collisions with focused Gaussian pulses, including a bremsstrahlung and an inverse Compton source for nonlinear Breit-Wheeler and a Gaussian electron beam for nonlinear trident, we find the position of the tunneling parameter regime to be well defined and robust.