Transitioning from Perturbative to Non-Perturbative Power Counting in the 1S0 Channel of NN Scattering*

The Pionless Effective Field Theory (EFT) for the 1S0 channel of the two-nucleon system is effective primarily around the threshold. Consequently, there have been efforts to extend Pionless EFT to higher momenta by incorporating either higher-order operators or a dibaryon field non-perturbatively. In this presentation, I will discuss a method that allows for starting with a perturbative power counting approach for certain low-energy constants at higher momenta, which remains effective non-perturbatively at lower momenta, including the threshold region.