Speaker
Description
Neutron dark decays have been suggested as a solution to the discrepancy between bottle and beam experiments, providing a dark matter candidate that can be searched for in halo nuclei. The free neutron in the final state following the decay of $^{6}$He into $^{4}$He + n + χ provides an exceptionally clean detection signature when combined with a high efficiency neutron detector. We will report on on the results of an experiment performed at GANIL using the unique neutron detector TETRA and the high-intensity 6He+ beam. A search for a coincident neutron signal resulted in an upper limit on a dark decay branching ratio of Brχ ≤ 4.0 × 10$^{-10}$ (95% C.L.). Using the dark neutron decay model proposed originally by Fornal and Grinstein [1], we translate this into an upper bound on a dark neutron branching ratio of $\mathcal{O}$(10$^{-5}$), improving over global constraints by one to several orders of magnitude depending on mχ [2].
References
[1] B. Fornal and and B. Grinstein, Phys. Rev. Lett. 120 (2018) 191801.
[2] L. Lejoubioux et al., Phys. Rev. Lett. 132 (2024) 132501.
