Non-perturbative methods for NN singular interactions

Chiral Effective Field Theory ( $$\chi $$ EFT) has been extensively used to study the NN interaction during last three decades. In Theories (EFTs) renormalization is performed order by including necessary counter terms. Due strong character of a non-perturbative resummation needed. this work, we will review some methods proposed completely remove cut-off dependencies. The covered are with boundary conditions, one term in momentum space (or equivalently subtractive renormalization) and exact N/D method. equivalence between up condition be checked showing results system. method allows go beyond others, using toy model it shown how can renormalize singular repulsive interactions.