We discuss in rather general terms the properties of space-like baryon transition form factors. In particular, we argue why these are necessarily complex-valued, what can be deduced from the respective phase motion, and why dealing with real-valued transition form factors in general leads to misleading results. For illustration, the transition form factors for the Roper resonance as derived in the Jülich–Bonn–Washington framework are discussed. Abstract Published by the Jagiellonian University 2026 authors
Hanhart et al. (Tue,) studied this question.