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Abstract It is shown that contrary to claims of Lebiedowicz et al. (Phys Rev D 105(1):014022, 2022) the formulated in the proper physical variables Low theorem (Low in Phys Rev 110(4):974–977, 1958) for soft photon emission does not require any modification. We also reject the criticism in Lebiedowicz et al. (2022) of the papers (Burnett and Kroll in Phys. Rev. Lett. 20:86–88,1968; Lipatov in Nucl Phys B 307:705–720, 1988). At the same time, we identify some inaccuracies in Burnett and Kroll (1968) in the presentation of the soft-photon theorem for the case of spin-one-half particles. We also point out shortcomings in consideration of the Low theorem in the classic textbooks (Berestetskii et al. in Quantum electrodynamics. Pergamon Press, Oxford, 1982; Lifshitz and Pitaevsky in Relativistic quantum theory, part 2, Fizmatlit, 2002).

Abstract We analyse the cross-section of events with Large Rapidity Gaps observed in proton–lead collisions by the CMS Collaboration ( arXiv:2301.07630 ). The role of the transverse size of elementary pN amplitude is discussed. We emphasize that the cross-section of incoming proton dissociation caused by the photon radiated off the lead ion is close to the value of $$d\sigma /d\Delta \eta ^F$$ d σ / d Δ η F measured by the CMS, and it is not clear why there is no room in the data for the Pomeron-induced contribution