{"arxiv_id":"2611.15852","title":"The Dark Side of the Periodic Table: Theory and Signatures of Nuclear Atomic Dark Matter","abstract":"We study the theory and signatures of a Mirror Twin Higgs (MTH) scenario in which stable twin neutrons constitute most of the dark matter (DM), while a subdominant component of twin elements survives as nuclear atomic dark matter (naDM). This framework offers a solution to the $matter~coincidence~problem$ ($\\Omega_{\\rm DM}\\simeq5\\Omega_b$), as the twin $\\mathbb{Z}_2$ symmetry can correlate the visible and DM mass scales and their number densities. We analyze twin nucleon freeze-out and the onset of twin Big Bang nucleosynthesis (BBN) to estimate the total naDM abundance, and determine which elements in the dark periodic table could be populated. An appreciable but subdominant naDM component generally requires a fractional nucleon mass splitting near the percent level, with twin-BBN creating heavy elements up to twin carbon. Strong twin neutron-proton scattering allows nearly all of the dark matter, not only the atomic sub-component, to participate in $dark~acoustic~oscillations$ (DAO) at early times, giving rise to a characteristic two-stage DAO signature that may be detected with future cosmological probes. Interactions between the twin and visible sectors, including the irreducible Higgs portal, make this scenario a well-motivated target for future directional direct-detection searches, and the naDM sub-component is expected to exhibit highly exotic astrophysics. We outline a supersymmetric twin Froggatt-Nielsen realization in which spontaneous $\\mathbb{Z}_2$ breaking in the flavon sector can generate the required fermion spectrum and Higgs potential.","primary_cat":"hep-ph","cross_cats":["astro-ph.CO"],"submitted_at":"2026-11-11T19:00:01+00:00","latest_version":1,"source":"arxiv","source_label":"arXiv","source_url":null,"has_pdf":true,"has_source":false,"verdict":"CONDITIONAL","confidence":"HIGH","one_line_summary":"A model where twin neutrons dominate dark matter and a twin nuclear-atomic subcomponent arises, solving the coincidence problem and producing observable signatures.","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","upvotes":0,"downvotes":0,"pith_score":0,"inbound_count":0,"_links":{"html":"https://pith.science/paper/2611.15852","verdict":"/api/v1/verdicts/2611.15852"}}