Interpretation of infrared scales in experimentally relevant EFT bounds

Determine whether effective-field-theory bounds intended for comparison with experiment should be formulated as purely mathematical bounds independent of infrared scales or as detector-level bounds that incorporate an experimental infrared resolution.

Background

The paper distinguishes between mathematical unitarity bounds for an isolated long-range quantum system and bounds extracted from finite experimental setups. The former need not contain an infrared scale, whereas detector environments, finite observation times, external fields, and absorption can introduce experimentally relevant infrared resolutions.

The authors leave unresolved which type of bound should be compared with experiment in general. They emphasize that, for the solvable Coulomb plus inverse-square model, the infrared dependence generated by naive short-range perturbation theory is an artifact rather than genuine detector dependence, but they do not settle the broader question for general effective field theories.

References

It is not clear to us whether, in general, the EFT bounds that should be compared with experiment are the purely mathematical bounds, independent of infrared scales, or bounds formulated directly for detector-level observables, which necessarily involve an experimental infrared resolution.

— Unitarity and the Forward Direction in Theories with Long-Range Forces  (2609.16896 - Lippstreu, 15 Sep 2026) in Section 'Conclusions', subsection 'Should EFT bounds contain IR scales?'