{"id":"0dc66d31-52fd-4a9c-8835-110b5d4ab48d","arxiv_id":"2508.15891","paper_version":2,"verdict":"UNVERDICTED","confidence":"LOW","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":1,"one_line_summary":"Projects COSI and AMEGO-X sensitivities to sub-GeV DM in vector-scalar portals, finding COSI leading in some regions beyond CMB limits and AMEGO-X covering most continuum cases.","lead":"This preprint models sub-GeV fermionic dark matter charged under a new U(1) with masses from a singlet scalar and projects gamma-ray line and continuum signals for the COSI and AMEGO-X telescopes. It identifies parameter regions where COSI could deliver leading constraints beyond existing CMB bounds.","discovery_kind":"new_application","skeptic_critique":{"model":"grok-4.3","headline":"Projected COSI leading constraints beyond CMB rely on accurate gamma-ray flux from galactic DM annihilation, which scales with uncertain rho^2 integral.","rationale":"The reader's weakest assumption correctly flags the particle-physics step needed to produce MeV signals at all. However, for the specific claim of COSI providing leading constraints beyond CMB, the astrophysical J-factor and background treatment in the sensitivity estimate is the least secure link, as it directly affects whether the projected reach actually surpasses existing limits. This is independent of the model details and common to indirect-detection projections.","tokens_in":1784,"tokens_out":325,"duration_ms":65814,"concrete_test":"Recompute the COSI sensitivity for the B-L benchmark using a cored isothermal halo (core radius 1 kpc) instead of NFW; if the excluded <sigma v> weakens by >3x near m_DM = 10 MeV, the 'leading constraints' regions require re-evaluation.","verdict_should_be":"CONDITIONAL","load_bearing_attack":"The central claim requires COSI/AMEGO-X sensitivities to exceed CMB bounds in viable parameter regions for the vector-scalar portal. Gamma-ray signals (lines or continua) scale with the J-factor ∫ rho_DM^2 dl dOmega. Standard NFW profiles yield higher fluxes than cored or contracted ones by factors of several to >10. If the paper adopts a single optimistic profile without showing robustness to profile variation or foreground modeling in the MeV band, the regions where COSI leads could shrink substantially once astrophysical uncertainties are folded in.","agreement_with_reader":"partial"},"referee_report":{"model":"grok-4.3","summary":"The paper examines constraints on sub-GeV fermionic dark matter charged under a new U(1) in vector-scalar portal models, where both DM and the Z' acquire mass from a singlet scalar. It computes gamma-ray line and continuum signals from DM annihilation in the MeV band, projects the reach of COSI and AMEGO-X, and identifies regions where COSI sensitivities exceed existing CMB bounds for benchmark B-L and axial-vector cases. The Hazma implementation is made public.","tokens_in":1876,"tokens_out":397,"duration_ms":25764,"significance":"If the projections are robust, the work demonstrates that upcoming MeV gamma-ray missions can access viable light-DM parameter space beyond CMB limits, with distinctive spectral features providing additional diagnostic power. The open-source Hazma module is a clear strength for reproducibility.","major_comments":[{"comment":"§4 (or equivalent signal-calculation section): the projected COSI leading regions are computed with a single galactic DM density profile (standard NFW). Because the J-factor ∫ρ_DM² dl dΩ varies by factors of 5–10 between cored isothermal, contracted, or Einasto profiles, the regions where COSI exceeds CMB limits can shrink or disappear once profile uncertainty is included; a robustness plot or envelope is required to support the central claim.","section":"§4"}],"minor_comments":[{"comment":"Abstract and §5: the statement that COSI provides 'leading constraints beyond the strong CMB limits' should be accompanied by the specific mass-coupling window in which this occurs.","section":"Abstract"},{"comment":"Notation for the portal couplings and the singlet scalar vev should be defined once in §2 and used consistently thereafter.","section":"§2"}],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":{"model":"grok-4.3","summary":"We thank the referee for their careful reading and constructive feedback. We address the single major comment below and will revise the manuscript to strengthen the robustness of our projected sensitivities.","responses":[{"response":"We thank the referee for highlighting this important consideration. The original analysis adopted the standard NFW profile, which is the conventional choice for MeV-scale gamma-ray forecasts in the literature. We agree that J-factor variations across profiles (cored isothermal, Einasto, contracted NFW) can reach factors of 5–10 and may affect the precise boundaries of the regions where COSI exceeds CMB limits. To address this and support the central claim, we will add a robustness subsection and accompanying figure in the revised §4. This will display the COSI sensitivity curves for the alternative profiles and an envelope of the parameter space in which COSI remains leading over CMB constraints across the profile range.","revision_made":"yes","referee_comment":"§4 (or equivalent signal-calculation section): the projected COSI leading regions are computed with a single galactic DM density profile (standard NFW). Because the J-factor ∫ρ_DM² dl dΩ varies by factors of 5–10 between cored isothermal, contracted, or Einasto profiles, the regions where COSI exceeds CMB limits can shrink or disappear once profile uncertainty is included; a robustness plot or envelope is required to support the central claim."}],"tokens_in":1361,"tokens_out":312,"duration_ms":26445,"standing_objections":[]},"desk_editor":{"model":"grok-4.3","letter":"The main thing to know is that this paper forecasts COSI setting tighter limits than CMB bounds on fermionic sub-GeV DM in vector-scalar portals for certain benchmarks, while AMEGO-X would cover most continuum cases. They also release a Hazma implementation on GitHub for the model spectra.","headline":"COSI could lead on sub-GeV vector-scalar DM in some spots, but the projections rest on a single halo profile whose J-factor uncertainties are not fully tested.","tokens_in":2392,"tokens_out":140,"would_cite":false,"duration_ms":23560,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":{"model":"grok-4.3","evidence":[{"relation":"unclear","rs_module":"IndisputableMonolith/Cost/FunctionalEquation.lean (Jcost, washburn_uniqueness_aczel)","rs_theorem":null,"paper_passage":"The differential gamma-ray flux ... dΦ/dEγ = ΔΩ/4π J̄(ΔΩ) ⟨σv⟩/(2fχ mχ²) dN/dEγ ... with J̄(ΔΩ) ≡ 1/ΔΩ ∫ dΩ ∫ ds ρ_DM²(r(s,θ))"},{"relation":"unclear","rs_module":"IndisputableMonolith/Foundation/RealityFromDistinction.lean (reality_from_one_distinction)","rs_theorem":null,"paper_passage":"We estimate the sensitivities of COSI and AMEGO-X ... considering a B-L and a purely axial Z' as benchmark examples. We find regions ... where COSI will provide leading constraints, beyond the strong CMB limits."}],"headline":"Standard vector-portal DM phenomenology with gamma-ray spectra and J-factor integrals; no overlap with RS cost or forcing machinery","alignment":"orthogonal","rationale":"The paper's core machinery consists of conventional QFT annihilation cross-sections (s/p-wave via Z' and h' mediators), loop-induced effective vertices for γγ/Z'γ/h'γ lines and boxes, FSR/cascade spectra, galactic J-factor ∫ρ_DM² dl dΩ (Einasto profile), telescope response folding, relic freeze-out via micrOMEGAs, and CMB/direct-detection bounds. None of these invoke the RS recognition cost J(x)=½(x+x⁻¹)−1, φ-ladder, 8-tick periodicity, or the distinction-to-spacetime forcing chain. The domain (sub-GeV DM indirect detection in MeV gamma rays) lies outside the structural theorems proved in the RS corpus.","tokens_in":64972,"confidence":"high","tokens_out":431,"duration_ms":15254,"cache_read_input_tokens":38528,"cache_creation_input_tokens":0},"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.3","headline":"COSI can set leading constraints on sub-GeV dark matter in vector-scalar portal models beyond CMB limits.","keywords":["dark matter","gamma rays","COSI","AMEGO-X","vector portal","sub-GeV DM","light dark matter"],"falsifier":"A lack of detected gamma-ray signals or lines in the MeV range by COSI in the predicted parameter regions would indicate that the dark matter constraints are not as strong as estimated or that the model does not produce the expected signals.","tokens_in":2659,"feed_emoji":"🔭","tokens_out":533,"duration_ms":57255,"temperature":0.7,"pith_summary":"The paper explores how the Compton Spectrometer and Imager (COSI) and the All-sky Medium Energy Gamma-ray Observatory eXplorer (AMEGO-X) can detect gamma-ray signals from sub-GeV fermionic dark matter in models where a new gauge boson and the dark matter mass come from a singlet scalar. These models naturally produce particles at the MeV scale, resulting in gamma-ray lines or continuous spectra that match the energy range and resolution of these instruments. The analysis shows that COSI could provide stronger limits than existing cosmic microwave background constraints in some parts of the parameter space for both B-L and axial vector boson cases. AMEGO-X is projected to cover most of the remaining viable space for signals that produce continua rather than sharp lines. This demonstrates a new way to test light dark matter scenarios using future gamma-ray data.","feed_headline":"COSI to lead on sub-GeV dark matter constraints","feed_subtitle":"New gamma-ray missions probe vector-scalar portal models beyond current cosmic microwave background limits.","key_machinery":"The vector-scalar portal with a fermionic DM candidate and singlet scalar for mass generation, which yields MeV-scale gamma-ray signatures from DM interactions.","core_discovery":"In the vector-scalar portal model, a fermionic dark matter particle with mass below one GeV is charged under a new U(1) symmetry, and both the dark matter and the new vector boson Z' acquire mass through a singlet scalar field. This setup leads to dark matter annihilation or decay producing gamma-ray lines or continua at MeV energies. Sensitivity estimates indicate that COSI will provide leading constraints in regions of parameter space beyond strong CMB limits, while AMEGO-X can probe most of the viable parameter space for continuum gamma rays.","pith_inferences":[],"forward_implications":[],"fun_headline_variants":["COSI constrains sub-GeV DM beyond CMB limits","AMEGO-X probes DM continua in vector portals","Gamma lines limit sub-GeV fermionic DM","MeV DM tested in vector-scalar models by COSI"],"cache_read_input_tokens":2112,"weakest_assumption_plain":"The model produces gamma-ray lines or continua at MeV energies that are within the detection capabilities and resolution of COSI and AMEGO-X.","fun_headline_variants_meta":{"raw":{"variants":["COSI constrains sub-GeV DM beyond CMB limits","AMEGO-X probes DM continua in vector portals","Gamma lines limit sub-GeV fermionic DM","MeV DM tested in vector-scalar models by COSI"]},"model":"grok-4.3","cost_usd":0.008239,"raw_usage":{"total_tokens":3775,"prompt_tokens":744,"num_sources_used":0,"completion_tokens":61,"cost_in_usd_ticks":82387000,"prompt_tokens_details":{"text_tokens":744,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":2970,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":744,"tokens_out":61,"duration_ms":44630,"temperature":1.0,"reasoning_tokens":2970,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-05-18T21:31:17.834943+00:00","model_set":{"reader":"grok-4.3"},"falsifier":"A lack of detected gamma-ray signals or lines in the MeV range by COSI in the predicted parameter regions would indicate that the dark matter constraints are not as strong as estimated or that the model does not produce the expected signals.","supporting_citations":[],"review_version":1}