Non-trivial effects of sourceless forces for spinors: toward an Aharonov–Bohm gravitational effect? Luca Fabbri, Flora Moulin and Aurélien Barrau Eur. Phys. J. C, 79 10 (2019) 875 Published online: 24 October 2019 DOI: 10.1140/epjc/s10052-019-7380-5