{"id":"586ec169-fc53-4380-89d3-1db48ee26bfe","arxiv_id":"2607.11876","paper_version":1,"verdict":"CONDITIONAL","confidence":"LOW","novelty_score":5.5,"correctness_risk":"medium","formal_verification":"none","parameter_count":2,"one_line_summary":"DESI DR1 full-shape plus Planck/ACT CMB constrain ultra-light axions to as little as 0.3% of matter density near 10^{-29} eV, more than doubling prior CMB-only reach.","lead":"New DESI DR1 full-shape galaxy clustering plus Planck and ACT CMB data tighten limits on ultra-light axions as a dark-matter subcomponent. For the lightest masses the joint analysis more than doubles the strength of CMB-only bounds, setting the tightest limits yet in that window.","discovery_kind":"extension","skeptic_critique":{"model":"grok-4.5","headline":"No significant objection identified beyond the abstract-only limitation already flagged by the Reader; the EFT-bias concern is correctly load-bearing but cannot be sharpened without the full text.","rationale":"The Reader’s weakest-assumption statement already isolates the single load-bearing condition for the strongest claim. With only the abstract in hand, no sharper technical flaw (e.g., an unstated prior, an inconsistent transfer-function treatment, or a misapplied mass-window approximation) can be diagnosed. The abstract’s language is standard for a data-driven constraint update, the improvement factor is stated quantitatively, and the mild LRG preference that disappears with CMB data is reported transparently. Therefore the CONDITIONAL / LOW-confidence verdict is appropriate and needs no adjustment. The concrete test above simply operationalizes the same EFT-bias concern so that it can be settled when the full analysis becomes available.","tokens_in":2110,"tokens_out":453,"duration_ms":3950,"concrete_test":"Once the full paper or public likelihoods appear, recompute the joint posterior for m_a ∼ 10^{-29} eV after (i) tightening the k_max cut by 20 % and (ii) floating an additional EFT counterterm; if the 95 % upper limit on f_a moves by more than ∼30 % relative to the published value, residual modeling systematics are contaminating the headline improvement.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The paper’s central claim (most stringent ULA subcomponent bounds from DESI DR1 full-shape + Planck/ACT, >2\times improvement at the lightest masses) rests on the assumption that the EFT of LSS modeling of the DESI galaxy power spectra remains unbiased across the quoted mass window and scale cuts. Because only the abstract is available, residual theoretical systematics that could artificially tighten or shift the reported f_a bounds cannot be inspected. The abstract itself flags that higher masses will require concurrent modeling improvements, confirming that the authors treat this as the limiting factor. No internal inconsistency or circularity is visible in the abstract; the concern is purely the unverified modeling fidelity that the Reader already identified.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.5","summary":"This manuscript reports updated constraints on ultra-light axions (ULAs) as a subcomponent of dark matter in the mass window 10^{-32}–10^{-24} eV, obtained from a joint full-shape analysis of DESI DR1 galaxy power spectra with Planck and ACT CMB data, using methods based on the Effective Field Theory of Large Scale Structure. The abstract claims that the joint analysis improves CMB-only bounds by more than a factor of two at the lightest masses, with ULAs limited to as little as 0.3% of the total matter density near m_a ∼ 10^{-29} eV, constituting the most stringent limits to date. A mild preference for a ULA subcomponent near m_a ≈ 10^{-26} eV in the DESI LRG sample is reported, mirroring earlier BOSS hints, but is stated to vanish upon combination with CMB data. The abstract notes that extending constraints to m_a ≳ 10^{-25} eV will require both smaller-scale data and concurrent improvements in theoretical modeling.","tokens_in":2267,"tokens_out":1071,"duration_ms":29160,"significance":"If the quantitative bounds and the claimed factor-of-two improvement hold under full scrutiny of the analysis pipeline, the work would deliver the tightest existing limits on ULA dark-matter fractions across a cosmologically important mass window and would illustrate the power of combining DESI full-shape clustering with CMB data for dark-sector constraints. Transparent reporting of a DESI-only preference that disappears with CMB is a methodological strength. The adoption of EFT-of-LSS methods is appropriate in principle for the scales involved, and the results would be of clear interest to both the cosmology and axion communities. Credit is due for framing the higher-mass regime as limited by modeling rather than data alone.","major_comments":[{"comment":"The central quantitative claims—more than a factor-of-two improvement over CMB-only constraints and f_a ≲ 0.3% of total matter density near m_a ∼ 10^{-29} eV—are load-bearing for the paper’s significance. With only the abstract available, these claims cannot be checked against the likelihood pipeline, scale cuts, covariance treatment, posterior contours, or direct CMB-only versus joint comparisons. The full manuscript must present these results with explicit figures and tables so that the improvement factor and the 0.3% bound can be independently assessed.","section":"Abstract"},{"comment":"The abstract correctly identifies that probing m_a ≳ 10^{-25} eV requires concurrent improvements in theoretical modeling. The claimed unbiased improvement across the full quoted window nevertheless rests on the assumption that EFT-of-LSS counterterms and the adopted scale cuts remain adequate at intermediate masses. Residual theoretical systematics that could artificially tighten or shift the reported f_a(m_a) bounds must be quantified (e.g., via mock-based validation, theory-error budgets, or explicit scale-cut stability tests); without that demonstration the ‘most stringent limits to date’ claim is not fully supported.","section":"Abstract (final sentence)"},{"comment":"The mild DESI LRG preference near m_a ≈ 10^{-26} eV that vanishes with CMB data is reported transparently, but the manuscript must show that this feature is not driven by unmodeled systematics in the DESI-only analysis (sample selection, multipole range, or EFT nuisance marginalization). A clear comparison of DESI-only versus joint posteriors, with nuisance-parameter diagnostics, is required to establish that the preference is statistical rather than systematic.","section":"Abstract"}],"minor_comments":[{"comment":"The abstract is clear and appropriately cautious. In the full manuscript the definition of the ULA fraction f_a (relative to total matter versus dark matter only) should be stated unambiguously at first use, and the precise DESI samples, redshift bins, and multipoles employed should be listed early.","section":"Abstract"},{"comment":"Without the full text it is not possible to assess figure clarity, notation consistency, or completeness of the reference list; these presentation items should be checked once the complete manuscript is available.","section":null}],"recommendation":"uncertain","confidential_remarks":"Only the abstract was supplied for this review. On that basis the science case appears free of circularity and the authors are transparent about both the vanishing DESI-only preference and the modeling ceiling at higher masses. A definitive recommendation (accept / minor_revision / major_revision) cannot be issued without the full analysis, figures, scale-cut tests, and EFT validation. If the full manuscript supplies those elements at the standard expected for DESI full-shape + CMB papers, the work is likely to be publishable after ordinary revisions; if the EFT systematics are left unquantified, major revision would be warranted."},"author_rebuttal":null,"desk_editor":{"model":"grok-4.5","letter":"The one thing you need to know is that this paper gives the first full-shape DESI DR1 constraints on ultra-light axions as a dark-matter subcomponent, and the joint run with Planck plus ACT improves the CMB-only limits by more than a factor of two for the lightest masses. Near 10^{-29} eV they push the allowed fraction down to 0.3 percent of total matter. That is a clean observational update if the pipeline holds.\n\nWhat is actually new is the data combination itself: DESI DR1 galaxy power spectra analyzed with current EFT-of-LSS methods, plus ACT and Planck. The mass window and the subcomponent framing are standard, but the quantitative improvement and the concrete numbers are not already in the literature. They also flag the mild DESI-only preference around 10^{-26} eV that mirrors earlier BOSS hints and then vanishes once CMB is added. That is reported without spin, which is useful.\n\nThe soft spot is exactly the one the abstract itself names: the EFT modeling of the galaxy spectra has to remain unbiased across the mass window and the scale cuts they chose. Higher masses will need smaller scales and better theory. Because we only have the abstract, we cannot inspect the likelihoods, covariances, or residual systematics, so the claimed tightening rests on that assumption. Nothing looks circular or forced.\n\nThis is for people who keep ULA bounds current or who run DESI full-shape pipelines. Anyone updating dark-sector constraints will want the numbers. It is important enough inside the field and uses the standard toolkit, so it deserves a serious referee rather than a desk reject. I would send it out.","headline":"First DESI DR1 full-shape ULA subcomponent bounds that tighten CMB-only limits by >2× at the lightest masses; the usual EFT modeling assumption is load-bearing and unchecked from the abstract alone.","tokens_in":2945,"tokens_out":453,"would_cite":true,"duration_ms":13559,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.5","headline":"Joint DESI DR1 full-shape and CMB data set the tightest limits yet on ultra-light axions as a dark-matter subcomponent across 10^{-32}–10^{-24} eV.","keywords":["ultra-light axions","dark matter","DESI DR1","full-shape analysis","CMB constraints","Effective Field Theory of LSS","galaxy power spectrum","cosmological parameters"],"falsifier":"A re-analysis of the same DESI DR1 spectra that employs a different set of scale cuts or an independent theoretical model of the galaxy power spectrum and finds an ultra-light-axion fraction bound that is weaker by a factor of two or more at m_a ∼ 10^{-29} eV would falsify the claimed improvement.","tokens_in":2978,"feed_emoji":"🌌","tokens_out":1045,"duration_ms":25382,"temperature":0.7,"pith_summary":"This paper claims that combining the full-shape DESI DR1 galaxy power spectra with Planck and ACT cosmic microwave background data produces the strongest existing upper bounds on the fraction of ultra-light axions that can contribute to the total matter density in the mass window 10^{-32} eV to 10^{-24} eV. The analysis relies on Effective Field Theory modeling of large-scale structure to extract information from the galaxy clustering spectra. At the lightest masses the joint data set improves on CMB-only limits by more than a factor of two; near 10^{-29} eV, for example, ultra-light axions are restricted to less than 0.3 percent of the total matter density. A mild preference for a small ultra-light-axion component around 10^{-26} eV appears in the DESI luminous red galaxy sample alone, but disappears once CMB measurements are included. The result therefore both tightens the allowed parameter space for these particles and shows that current hints of a detection do not survive the joint analysis.","feed_headline":"DESI and CMB cut lightest axion dark-matter share to 0.3%","feed_subtitle":"Joint full-shape analysis improves on CMB-only limits by more than a factor of two across 10^{-32}–10^{-24} eV.","key_machinery":"The full-shape analysis of the DESI DR1 galaxy power spectra performed with the Effective Field Theory of Large Scale Structure, jointly fitted with Planck and ACT CMB likelihoods; this supplies the additional late-time clustering information that tightens the ultra-light-axion fraction bounds.","core_discovery":"When DESI DR1 full-shape galaxy power spectra are analyzed jointly with Planck and ACT CMB data inside the Effective Field Theory of large-scale structure, the allowed fraction of ultra-light axions as a dark-matter subcomponent is reduced by more than a factor of two relative to CMB-only constraints at the lowest masses, reaching f_a ≲ 0.3 percent near m_a ∼ 10^{-29} eV and establishing the most stringent limits to date across the window 10^{-32}–10^{-24} eV.","pith_inferences":["The factor-of-two improvement at the lightest masses implies that forthcoming DESI data releases will begin to probe ultra-light-axion fractions below the 0.1 percent level if modeling systematics remain under control.","The disappearance of the BOSS-like preference once CMB data are added suggests that similar late-time clustering hints in other surveys are likely to be prior-volume or modeling artifacts rather than genuine signals.","Extending the same full-shape pipeline to smaller scales will test whether the current mass-window edge at 10^{-24} eV is a true physical boundary or merely a modeling limitation."],"forward_implications":["Ultra-light axions near 10^{-29} eV can constitute at most a few parts per thousand of the total matter density.","Any mild preference for an ultra-light-axion component around 10^{-26} eV seen in luminous red galaxy samples alone is erased by the addition of CMB data.","Future constraints at masses ≳ 10^{-25} eV will require both smaller-scale galaxy clustering and CMB lensing measurements and simultaneous advances in theoretical modeling.","CMB-only analyses are no longer the limiting factor for the lightest ultra-light axions once DESI full-shape information is included."],"fun_headline_variants":["DESI full-shape plus CMB halves lightest ULA dark-matter share to 0.3%","Joint DESI-Planck-ACT analysis cuts ULA fraction to 0.3% at 10^{-29} eV","DESI DR1 and CMB set tightest ultra-light axion limits across 10^{-32}-10^{-24} eV","ULA subcomponent capped at 0.3% of matter by DESI full-shape with ACT and Planck","Full-shape DESI spectra improve ULA bounds by factor >2 over CMB alone"],"cache_read_input_tokens":2304,"weakest_assumption_plain":"The Effective Field Theory modeling of the DESI galaxy spectra is assumed to remain free of residual theoretical bias across the mass window and scale cuts that are used, so that systematics do not artificially tighten or shift the reported bounds.","fun_headline_variants_meta":{"raw":{"variants":["DESI full-shape plus CMB halves lightest ULA dark-matter share to 0.3%","Joint DESI-Planck-ACT analysis cuts ULA fraction to 0.3% at 10^{-29} eV","DESI DR1 and CMB set tightest ultra-light axion limits across 10^{-32}-10^{-24} eV","ULA subcomponent capped at 0.3% of matter by DESI full-shape with ACT and Planck","Full-shape DESI spectra improve ULA bounds by factor >2 over CMB alone"]},"model":"grok-4.5","effort":"low","cost_usd":0.004296,"raw_usage":{"total_tokens":1370,"prompt_tokens":885,"num_sources_used":0,"completion_tokens":141,"cost_in_usd_ticks":42960000,"prompt_tokens_details":{"text_tokens":885,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":344,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":885,"tokens_out":141,"duration_ms":3456,"temperature":1.0,"reasoning_tokens":344,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-07-14T02:29:12.344593+00:00","model_set":{"reader":"grok-4.5"},"falsifier":"A re-analysis of the same DESI DR1 spectra that employs a different set of scale cuts or an independent theoretical model of the galaxy power spectrum and finds an ultra-light-axion fraction bound that is weaker by a factor of two or more at m_a ∼ 10^{-29} eV would falsify the claimed improvement.","supporting_citations":[],"review_version":1}