Is the "RG-invariant EFT'' for few-nucleon systems cutoff independent?

Understand

We consider nucleon-nucleon scattering using the formulation of chiral effective field theory which is claimed to be renormalization group invariant.

• The cornerstone of this framework is the existence of a well-defined infinite-cutoff limit for the scattering amplitude at each order of the expansion, which should not depend on a particular regulator form.
• Focusing on the $^3P_0$ partial wave as a representative example, we show that this requirement can in general not be fulfilled beyond the leading order, in spite of the perturbative treatment of subleading contributions to the amplitude.
• Several previous studies along these lines, including the next-to-leading order calculation by Long and Yang [Phys.