Document Type


Publication Date




Publication Title

Physical Review C






014001 (1-30)


The present work deals with e+−e pair production in the four-nucleon system. We first analyze the process as a purely electromagnetic one in the context of a state-of-the-art approach to nuclear strong-interaction dynamics and nuclear electromagnetic currents, derived from chiral effective field theory (χEFT). Next, we examine how the exchange of a hypothetical low-mass boson would impact the cross section for such a process. We consider several possibilities, that this boson is either a scalar, pseudoscalar, vector, or axial particle. The ab initio calculations use exact hyperspherical-harmonics methods to describe the bound state and low-energy spectrum of the A = 4 continuum, and they fully account for initial state interaction effects in the 3 + 1 clusters. While electromagnetic interactions are treated to high orders in the chiral expansion, the interactions of the hypothetical boson with nucleons are modeled in leading-order χEFT (albeit, in some instances, selected subleading contributions are also accounted for). We also provide an overview of possible future experiments probing pair production in the A = 4 system at a number of candidate facilities.


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Original Publication Citation

Viviani, M., Filandri, E, Girlanda, L., Gustavino, C., Kievsky, A., Marcucci, L.E., Schiavilla, R. (2022). X17 boson and the ³H(p, e⁺e⁻) ⁴He and ³He(n,e⁺e⁻) ⁴He processes: A theoretical analysis. Physical Review C, 105 (1), 1-30, Article 014001.