{"paper":{"title":"Observation of excited states in $^{20}$Mg sheds light on nuclear forces and shell evolution","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["nucl-th"],"primary_cat":"nucl-ex","authors_text":"A. A. Chen, A. Chester, A. Shotter, B. Davids, C. Andreoiu, C. Barnes, C. Burbadge, D. Burke, D. Kisliuk, E. McGee, E. Padilla-Rodal, G. Christian, G. Hackman, G. Hagen, G. R. Jansen, I.J. Thompson, J. D. Holt, J.Even, J. Henderson, J. Liang, J. Lighthall, J. Measures, J. S. Randhawa, J. Turko, M. Alcorta, M. Holl, M. Keefe, M. Moukaddam, M.Williams, O. Workman, P. Jassal, P. Navratil, R. Kanungo, R. Krucken, S. Cruz, S. Ishimoto, S. Kaur, S. R. Stroberg","submitted_at":"2019-01-07T10:38:06Z","abstract_excerpt":"The exotic Borromean nucleus $^{20}$Mg with $N$ = 8, located at the proton drip-line provides a unique testing ground for nuclear forces and the evolution of shell structure in the neutron-deficient region. We report on the first observation of proton unbound resonances together with bound states in $^{20}$Mg from the $^{20}$Mg($d$,$d'$) reaction performed at TRIUMF. Phenomenological shell-model calculations offer a reasonable description. However, our experimental results present a challenge for current first-principles nuclear structure approaches and point to the need for improved chiral fo"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1901.01741","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}