We map the physically realizable subspace of the parametrized post-Einsteinian (ppE) framework by imposing ghost-freedom, causality, unitarity, and EFT naturalness conditions. Only ~34% of the ppE parameter space currently explored by LIGO is physically realizable. EFT-informed priors yield constraints equivalent to ~3x more events and reduce computational cost by ~66%, corresponding to ~300 MWh savings per GWTC-3-scale analysis campaign. Part II of a trilogy on the S-sector EFT
Kenneth Cairampoma (2026) studied this question.