Relationship between GW observational bounds and causality/EFT-bootstrap constraints on higher-curvature Wilson coefficients

Determine whether the constraints derived from gravitational-wave observations of merging black holes (specifically bounds on quartic and, by expectation, cubic Riemann curvature operators such as those reported by Sennett et al. 2019) provide new or distinct information compared to the causality and unitarity-based effective field theory bootstrap constraints (such as those of Caron-Huot et al. 2021, 2022) on the Wilson coefficients of the higher-derivative Riemann curvature operators in the gravitational effective action of general relativity.

Background

Within the effective field theory of gravity, deviations from general relativity in pure gravity arise only through higher-derivative operators built from the Riemann tensor. Recent analyses have produced two types of constraints on these operators: (i) observational bounds from LIGO/Virgo on quartic Riemann terms (and by expectation on cubic terms) at scales set by black hole mergers, and (ii) sharp causality and unitarity-based bounds from the EFT bootstrap approach that relate cubic and quartic coefficients and impose positivity conditions.

The authors highlight that it is unclear whether these two regimes—observational gravitational-wave constraints and theoretical causality/positivity constraints—yield complementary or new information about the Wilson coefficients governing higher-curvature operators. Clarifying this relationship is important for interpreting current and future constraints on deviations from general relativity within EFT.