Can the Strong Interactions between Hadrons Be Determined Using Femtoscopy?

In the last decades, femtoscopic measurements from heavy-ion collisions have become a popular tool to investigate the strong interactions between hadrons. The key observables measured in such experiments are the two-hadron momentum correlations, which depend on the production mechanism of hadron pairs and the final-state interactions. Given the complexity of ultrarelativistic collision experiments, the source term describing the production mechanism can be modeled phenomenologically only based on numerous assumptions. The commonly employed approach for analyzing femtoscopic data relies on the Koonin-Pratt formula, which relates the measured correlation functions with the relative wave function of an outgoing hadron pair and a source term that is assumed to be universal. Here, we critically examine this universality assumption and show that, for strongly interacting particles such as nucleons, the interpretation of femtoscopic measurements suffers from a potentially large intrinsic uncertainty. We also comment on the ongoing efforts to explore three-body interactions using this experimental technique.