Resolution of the factor-of-two discrepancy in the subleading soft waveform

Resolve the factor-of-two discrepancy between the Self-Force EFT prediction and the classical soft-graviton-theorem prediction for the \(\omega\log^2\omega\) term in the massless-massless gravitational-scattering waveform.

Background

The paper compares the soft-frequency expansion of the 1SF waveform with predictions from classical soft-graviton theorems. The linear-memory 1/ω1/\omega term and the log⁡ω\log\omega tail agree with the external prediction, but the coefficient of the subleading ωlog⁡2ω\omega\log^2\omega term differs by an overall factor of two.

The authors do not resolve whether the discrepancy arises from the Self-Force calculation, the soft-theorem prediction, conventions, or an omitted contribution. The issue is therefore left as an explicitly unresolved consistency problem.

References

To date, we have not been able to resolve this discrepancy.

— Gravitational Radiation from Shockwave Scattering in the Self-Force EFT  (2609.09378 - Rosi, 8 Sep 2026) in Section 4, subsection “All-orders Post-Minkowskian series,” footnote following Eq. (soft-waveform-memory-tails); reiterated in Section 5, Conclusions