Renormalized coupling (${\lambda }_R(\mu )$)

A renormalized coupling is an interaction parameter defined by a specified finite renormalization condition or subtraction scheme at a scale $\mu$. Observables remain independent of that arbitrary scale when its running and the loop corrections are included consistently. The coupling itself, and higher-order coefficients in its renormalization-group beta function, can depend on the scheme; they should not be identified without qualification with a regulator-independent bare coefficient.