A Unified Framework for Effective Theories:Reconstructing Nine Adjacent Theories through the OS Model

This paper proposes a unified structural framework for nine major effective-theory–related formalisms, including Effective Field Theory (EFT), Wilsonian Renormalization Group, Heavy Quark Effective Theory, Soft-Collinear Effective Theory, and others. Using the OS Model---a hierarchical, observer-directional, and open/closed-system framework---we reconstruct each theory in a common coordinate system. This approach clarifies the characteristic domain, structural assumptions, and limitations of each theory, and demonstrates how the OS Model resolves or generalizes these limitations. The result is a higher-level theoretical structure that encompasses all nine theories as special parameter choices.