2025/12/21 by Shuang Zhang, Serdar Elhatisari, Zhang, Shuang +3
Earth and Planetary Sciences · Physics and Astronomy · #Cold Fusion and Nuclear Reactions #FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Phenomenology (hep-ph) #Nuclear Experiment (nucl-ex) #Nuclear Physics and Applications #Nuclear Theory (nucl-th) #Nuclear physics research studies
paper · doi:10.48550/arxiv.2512.18849
openalex publication_date 2025/12/21 · openalex created_date 2025/12/24 · openalex updated_date 2026/07/28
The quest to understand multi-neutron systems has a long history, and recent experimental efforts aim to probe candidate four-neutron configurations in neutron-rich light nuclei such as 8He and 7H via quasi-free knockout reactions. However, the ground-state energies of the hydrogen isotopes 6H and 7H are not yet well constrained, with substantial discrepancies across experimental analyses and theoretical predictions. Using ab initio nuclear lattice effective field theory with an ensemble of 282 chiral two- and three-nucleon forces, we perform a Bayesian uncertainty-quantified analysis of the ground-state energies of 6H and 7H. The marginal posteriors suggest single-neutron separation energy Sn(7H)=0.35+0.32-0.32 MeV, which kinematically disfavors sequential decay via 6H+n and thereby makes multi-neutron emission channels comparatively more relevant. Intrinsic densities indicate triton- and α-like clusters in 7H and 8He, respectively. By computing two-body and reduced four-body correlation functions, we find that the valence neutrons in the surface region of these systems form compact dineutrons that predominantly organize into approximately symmetric dineutron-dineutron configurations, with only a small but non-negligible fraction assembling into more compact tetraneutron-like substructures. In 7H, these components account for roughly 95% and 5% of the sampled four-neutron configurations, respectively, and 8He exhibits a similar hierarchy. For these configurations, we also extract the corresponding spatial and angular correlation patterns among the nucleons. These results provide nuclear-structure insights into the debate surrounding four-neutron clusters and complement ongoing experimental searches for tetraneutron signatures in light nuclei.