Professor Rinaldo Baldini-Ferroli, a senior scientist of the BESIII International Collaboration, passed away on the evening of February 21, 2026, in Rome, Italy. Rinaldo was affiliated with the Laboratori Nazionali di Frascati in Frascati, Italy, and joined the BESIII International Collaboration in 2008 as a representative of the institution. Rinaldo was also a trailblazer in China-Italy high-energy physics cooperation.

Rinaldo was an exceptional scientist and a deeply valued member of the BESIII collaboration. He made pioneering contributions to several key areas of BESIII physics, most notably in baryon electromagnetic form factors and hadron structure. His insight, dedication, and enthusiasm greatly advanced our understanding in these fields and have left a lasting impact on the BESIII physics program.

Currently, the study of the time-like electromagnetic form factors of baryons and antibaryons is one of the key research directions of BESIII Collaboration. A series of representative papers have been published, which hold significant scientific importance for understanding the mechanisms of hadron formation. As an example, in 2021, the BESIII collaboration measured the Born cross section of electron–positron annihilation reactions into a neutron and anti-neutron pair over a wide four-momentum transfer range from 4.0 to 9.5 GeV². For the first time, BESIII observed damped oscillatory behavior in the effective electromagnetic form factor (as shown in the figure below, published as a cover article in Nature Physics 17, 1200–1204 (2021). https://doi.org/10.1038/s41567-021-01345-6). The results imply that there is some not yet understood intrinsic dynamics responsible for these nearly orthogonal oscillations. Possible explanations include interference effects from final-state rescattering or the influence of a resonant structure.

Fig. 1 Deviation of the effective form factors from dipole law, indicating a periodic oscillatory behavior for both protons and neutrons.

Professor Rinaldo Baldini-Ferroli was one of the early advocates for these related measurements at BESIII and also one of the earliest Italian representatives in the BESIII collaboration, helping to pioneer new research directions in BESIII physics.

By the end of 2025, the BESIII experiment had published over 750 papers, establishing significant international influence in the fields of hadron spectroscopy, production and decay of charm hadrons, and baryon and hyperon physics.

The passing of Professor Rinaldo Baldini-Ferroli is a tremendous loss to the BESIII Collaboration. His scientific spirit and outstanding contributions to China-Italy scientific exchanges will forever be remembered in our hearts. We will carry forward his legacy, continue to deepen cooperation between China and Italy in particle physics.