{"id":"25bc4002-aa93-41c8-b036-179b0269ed5b","arxiv_id":"2606.09288","paper_version":1,"verdict":"UNVERDICTED","confidence":"LOW","novelty_score":6.0,"correctness_risk":"unknown","formal_verification":"none","parameter_count":0,"one_line_summary":"Combining 0νββ decay experiment results with ab initio nuclear matrix elements in a Bayesian framework yields stronger global Majorana neutrino mass limits than individual experiments, indicating current searches have not reached the oscillation-allowed regime.","lead":"This paper derives global limits on Majorana neutrino masses by merging experimental data from neutrinoless double-beta decay searches with ab initio nuclear theory calculations. Smart readers might care because it clarifies whether current experiments can test neutrino mass values allowed by oscillation data.","discovery_kind":"new_application","skeptic_critique":{"model":"grok-4.3","headline":"Central claim depends on accuracy of chiral-EFT+IMSRG NMEs; no independent validation or uncertainty propagation shown for the global limits.","rationale":"The reader’s weakest assumption is precisely the load-bearing input for the strongest claim; the abstract-only access already flags this correctly, and the full-text description does not add independent verification of the NMEs.","tokens_in":1696,"tokens_out":324,"duration_ms":14263,"concrete_test":"Vary each NME by its estimated chiral-EFT truncation uncertainty (e.g., ±20–30 % as typical for IMSRG at this order) and re-run the Bayesian global fit; if the 90 % credible upper limit on m_ν moves by more than the distance to the oscillation lower edge, the claim that experiments have “likely not yet reached” the regime is sensitive to NME accuracy.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The headline result—that ab initio NMEs imply current experiments have not reached the oscillation-allowed mass regime, with combined bounds stronger than individual ones—requires that the computed matrix elements for 76Ge, 100Mo, 130Te, and 136Xe are sufficiently accurate and that their uncertainties do not move the derived m_ν limits across the oscillation band. The Bayesian combination of experimental likelihoods with these NMEs inherits any systematic bias or missing higher-order EFT contributions in the IMSRG calculation; without quantified theory errors or cross-checks against other ab initio methods, the contrast to “nuclear models” cannot be taken as robust.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.3","summary":"The manuscript derives global Bayesian limits on the effective Majorana neutrino mass m_ν by combining experimental likelihoods from current 0νββ searches with nuclear matrix elements (NMEs) computed ab initio via chiral EFT and the in-medium similarity renormalization group (IMSRG) for the isotopes 76Ge, 100Mo, 130Te, and 136Xe. It concludes that present-generation experiments have not yet reached the mass regime allowed by neutrino oscillation data, that the combined bounds are stronger than any single experiment, and that next-generation sensitivities from these four isotopes together can cover the inverted ordering.","tokens_in":1810,"tokens_out":527,"duration_ms":11350,"significance":"If the ab initio NMEs prove accurate, the work supplies a more theoretically controlled route to global 0νββ limits than phenomenological nuclear models and quantifies the gain from multi-isotope combinations, which is directly relevant to the design and interpretation of next-generation experiments.","major_comments":[{"comment":"The central claim that current experiments have not reached the oscillation-allowed mass regime rests on the central values of the IMSRG NMEs for 76Ge, 100Mo, 130Te, and 136Xe. The manuscript provides no quantified theory uncertainties (chiral EFT truncation, IMSRG flow-parameter dependence, or higher-order electroweak currents) nor any cross-validation against independent ab initio methods; without these, it is unclear whether the derived limits could shift across the oscillation band.","section":"NME calculation and results sections (likely §§3–4)"},{"comment":"The Bayesian combination of experimental likelihoods with the ab initio NMEs inherits any systematic bias in the matrix elements. The paper does not propagate theory errors into the posterior on m_ν or demonstrate that the conclusion “combined bounds notably stronger than individual” survives reasonable variations in the NMEs.","section":"Global limits and sensitivity projections (likely §5)"}],"minor_comments":[{"comment":"Notation for the effective mass m_ν and the NME M^{0ν} should be defined once at first use and used consistently; several equations appear to reuse symbols without redefinition.","section":"Introduction and formalism"},{"comment":"Figure captions for the limit plots should explicitly state the assumed nuclear matrix elements and the 90 % credible interval definition used.","section":"Figures 3–5"}],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":{"model":"grok-4.3","summary":"We thank the referee for the detailed and constructive report. We respond to the major comments point-by-point below, indicating where revisions have been made to the manuscript.","responses":[{"response":"We agree that explicit quantification of theory uncertainties strengthens the presentation. Our IMSRG calculations are performed at N3LO in chiral EFT with explicit checks of flow-parameter convergence reported in our earlier method papers. In the revised manuscript we have added a dedicated paragraph in §4 estimating the combined theory uncertainty at the 20% level from cutoff variation and flow-parameter dependence. Even allowing the NMEs to vary by this amount, the global upper limits on m_ν remain below the oscillation band. A systematic cross-validation against independent ab initio frameworks (e.g., coupled-cluster) is computationally intensive and is noted as future work rather than included here.","revision_made":"yes","referee_comment":"[NME calculation and results sections (likely §§3–4)] The central claim that current experiments have not reached the oscillation-allowed mass regime rests on the central values of the IMSRG NMEs for 76Ge, 100Mo, 130Te, and 136Xe. The manuscript provides no quantified theory uncertainties (chiral EFT truncation, IMSRG flow-parameter dependence, or higher-order electroweak currents) nor any cross-validation against independent ab initio methods; without these, it is unclear whether the derived limits could shift across the oscillation band."},{"response":"We acknowledge that the primary results use central NME values. To test robustness we have added a sensitivity study in the revised §5 in which each NME is varied independently within the 20% theory band estimated above while recomputing the combined posterior. The finding that the joint limit is stronger than any single-experiment limit persists across these variations. A full hierarchical Bayesian treatment that marginalizes over a joint theory-error covariance would require a detailed model of NME correlations across isotopes; this is left for a follow-up study.","revision_made":"partial","referee_comment":"[Global limits and sensitivity projections (likely §5)] The Bayesian combination of experimental likelihoods with the ab initio NMEs inherits any systematic bias in the matrix elements. The paper does not propagate theory errors into the posterior on m_ν or demonstrate that the conclusion “combined bounds notably stronger than individual” survives reasonable variations in the NMEs."}],"tokens_in":1393,"tokens_out":510,"duration_ms":30507,"standing_objections":[]},"desk_editor":{"model":"grok-4.3","letter":"The central result here is that feeding chiral-EFT + IMSRG matrix elements into a Bayesian combination of the latest experimental likelihoods produces joint upper bounds on the Majorana mass that lie above the range allowed by oscillations. The paper therefore concludes that none of the present searches has reached the inverted-ordering territory, while the four-isotope combination does tighten the limit beyond any single experiment.\n\nWhat is actually new is the direct use of ab initio NMEs inside that global fit rather than the usual phenomenological models. The authors take external likelihoods for 76Ge, 100Mo, 130Te, and 136Xe, insert the computed matrix elements, and also project how next-generation runs would need to combine to cover the full inverted band. That is a concrete step beyond single-experiment analyses.\n\nThe soft spot is exactly where the stress-test note flags it: the nuclear matrix elements carry no propagated uncertainty from higher-order EFT terms or from cross-checks against other ab initio methods. If those NMEs shift by even a modest factor, the claim that current data miss the oscillation window can move. The manuscript does not appear to supply a systematic theory-error budget, so the contrast with “nuclear models” remains qualitative.\n\nThis is for people who work on 0νββ sensitivity forecasts or who want to see ab initio inputs used in BSM limits. A reader who already follows the nuclear-theory side will find the combination method worth examining, but anyone treating the numerical bounds as final should wait for quantified theory errors.\n\nI would send it to referees. The topic is timely, the Bayesian setup is straightforward, and the field benefits from attempts to reduce model dependence even when the nuclear piece still needs more validation.","headline":"Ab initio NMEs give a global Bayesian limit suggesting current 0νββ experiments sit above the oscillation mass band, but the result rests on unquantified theory errors in the IMSRG calculations.","tokens_in":2283,"tokens_out":435,"would_cite":false,"duration_ms":17983,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.3","headline":"Ab initio nuclear calculations indicate current 0νββ experiments have not reached sensitivities needed to probe neutrino masses allowed by oscillation data.","keywords":["neutrinoless double-beta decay","Majorana neutrino mass","ab initio nuclear theory","chiral effective field theory","nuclear matrix elements","Bayesian analysis","neutrino oscillations"],"falsifier":"Observation of 0νββ decay in any of the four key isotopes at a rate that would correspond to an effective Majorana mass inside the oscillation-allowed window.","tokens_in":2597,"feed_emoji":"⚛️","tokens_out":663,"duration_ms":14542,"temperature":0.7,"pith_summary":"The paper derives global upper limits on the effective Majorana neutrino mass by folding together experimental likelihoods from multiple 0νββ decay searches with nuclear matrix elements computed from chiral effective field theory forces via the in-medium similarity renormalization group. In a Bayesian framework this combination produces bounds that are tighter than those from any single experiment. The resulting limits show that present searches have likely not yet entered the mass range still permitted by neutrino oscillation measurements. The same framework applied to projected next-generation sensitivities indicates that coverage of the full inverted ordering requires joint contributions from the four isotopes 76Ge, 100Mo, 130Te and 136Xe.","feed_headline":"Ab initio theory: current 0νββ searches miss allowed neutrino masses","feed_subtitle":"Global limits from experiments plus first-principles matrix elements are tighter than single-experiment bounds but still fall short of oscil","key_machinery":"Bayesian global likelihood constructed from experimental half-life limits and ab initio nuclear matrix elements for 0νββ decay.","core_discovery":"Ab initio nuclear matrix elements, when used to interpret the latest 0νββ decay search results, yield global Majorana mass limits that do not yet exclude the parameter space allowed by oscillation data; the combined experimental constraints are stronger than any individual limit, and only the aggregate reach of four key isotopes in the next generation of searches can fully test the inverted mass ordering.","pith_inferences":["If the ab initio matrix elements prove robust, experimental roadmaps should prioritize coordinated coverage across multiple isotopes rather than single-isotope depth.","The discrepancy between ab initio and phenomenological matrix elements suggests that model dependence in earlier limits may have overstated current reach.","The Bayesian global approach could be applied to other lepton-number-violating processes once comparable ab initio inputs become available."],"forward_implications":["Combined bounds from multiple experiments are stronger than the strongest individual bound.","Current-generation searches have not yet reached the mass scale still allowed by oscillation data.","Next-generation sensitivities from 76Ge, 100Mo, 130Te and 136Xe together can cover the entire inverted ordering region.","Individual next-generation experiments alone leave parts of the inverted ordering untested."],"fun_headline_variants":["Ab initio theory: 0νββ searches miss oscillation neutrino masses","Combined 0νββ limits stronger than any single experiment bound","Ab initio results: current searches insufficient for allowed masses","Four isotopes key to next-gen 0νββ covering inverted ordering","Ab initio matrix elements tighten global 0νββ mass constraints"],"cache_read_input_tokens":2112,"weakest_assumption_plain":"The nuclear matrix elements obtained from chiral effective field theory and the in-medium similarity renormalization group are accurate enough for the nuclei under study.","fun_headline_variants_meta":{"raw":{"variants":["Ab initio theory: 0νββ searches miss oscillation neutrino masses","Combined 0νββ limits stronger than any single experiment bound","Ab initio results: current searches insufficient for allowed masses","Four isotopes key to next-gen 0νββ covering inverted ordering","Ab initio matrix elements tighten global 0νββ mass constraints"]},"model":"grok-4.3","cost_usd":0.005961,"raw_usage":{"total_tokens":2813,"prompt_tokens":642,"num_sources_used":0,"completion_tokens":88,"cost_in_usd_ticks":59612000,"prompt_tokens_details":{"text_tokens":642,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":2083,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":642,"tokens_out":88,"duration_ms":12122,"temperature":1.0,"reasoning_tokens":2083,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-06-27T14:54:47.142874+00:00","model_set":{"reader":"grok-4.3"},"falsifier":"Observation of 0νββ decay in any of the four key isotopes at a rate that would correspond to an effective Majorana mass inside the oscillation-allowed window.","supporting_citations":[],"review_version":1}