Assess whether perturbative loop corrections can resolve the soft-photon puzzle and clarify their non-perturbative connection

Determine whether perturbative loop corrections to soft theorems in QED and QCD can account for the experimentally observed anomalous soft-photon excess, and elucidate how these corrections relate to non-perturbative physics such as hadronization and long space-time scales in hadronic processes.

Background

The paper summarizes the infrared structure of QED and QCD at loop level, noting that while leading-power soft-photon theorems in QED remain uncorrected at loop level, subleading terms and certain massless limits do receive loop corrections (e.g., α_s^3/ω at three loops for photons and α_s log terms at next-to-leading power).

Despite these advances, the authors explicitly state that it is not clear whether such perturbative corrections can explain the anomalous soft-photon production observed in experiments, nor how these results interface with non-perturbative phenomena. This frames a concrete open question about the scope of perturbative corrections in resolving the soft-photon puzzle and their relation to non-perturbative QCD.