{"id":"ae9e08af-ad4d-409c-804f-a0b5bc93920a","arxiv_id":"2412.13349","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"Axial non-standard neutrino interactions can mimic or be disentangled from nucleon form-factor effects in neutral-current quasi-elastic and resonance scattering, and tau-flavor couplings may already be bounded by KamLAND atmospheric data.","lead":"This paper studies how non-standard neutrino interactions (NSI) would show up in quasi-elastic and resonant neutral-current scattering of neutrinos off nuclei, once the poorly known nucleon form factors are taken into account. It finds that poorly constrained axial NSI couplings could produce large, identifiable deviations in argon cross sections, and sketches two new ways to detect them.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Missing 2p-2h nuclear contribution in the SM baseline undermines the summary's '>30% excess implies isoscalar axial NSI' criterion.","rationale":"This is the single most load-bearing concern because it targets the paper's central quantitative interpretation, not an ancillary estimate. The KamLAND-bound estimate is explicitly labeled an over-simplification and is not needed for the argon cross-section results; the alpha-factorization in Eq. (34) was checked at the 10% level and concerns only the propagation of form-factor uncertainties. In contrast, the 2p-2h omission changes the SM baseline itself, and the summary's '>30% excess implies isoscalar NSI' criterion has no caveat for this known missing channel. The authors cite Refs. [43-46] showing 2p-2h is significant and can be included, so the omission is a limitation of the present illustrative calculation rather than a fundamental obstruction; this is why the verdict should remain conditional rather than reject or accept. Agreement with the reader is partial: the reader identified the KamLAND scaling as the weakest assumption and mentioned nuclear effects only as a qualifier, whereas we locate the most fragile point in the missing 2p-2h contribution.","tokens_in":22926,"tokens_out":17920,"duration_ms":164193,"concrete_test":"Recompute the SM QE NC cross-section band for argon with 2p-2h switched on in GiBUU, using the same form-factor inputs and QE-like event selection as Figs. 2 and 3. If the central SM prediction rises by more than about 15% anywhere in the E_nu = 0.5-4 GeV range, the 30% NSI threshold must be re-derived; if the shift is below 5%, the criterion is robust.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The paper's summary states that 'an excess of more than 30% can be interpreted as axial isoscalar NSI' (Section VI). This threshold is derived from the GiBUU QE cross-section bands in Section V, where the authors explicitly say 'we omit the contribution from two particles-two holes (2p-2h) excitations' (Refs. [43-45]). 2p-2h processes are not a form-factor uncertainty; they are known to contribute at the tens-of-percent level to QE-like NC cross sections in argon at the energies considered. Because the SM baseline in Figs. 2 and 3 contains no 2p-2h, a measured NC QE-like rate could sit more than 30% above that baseline even in the absence of NSI. The isovector deficit argument is less affected, but the isoscalar signature (excess only) is directly contaminated. The abstract's phrase 'distinct from the uncertainties induced by the form factors' remains true, but the stronger interpretation in the summary overreaches until the SM baseline includes 2p-2h.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper examines how neutral-current non-standard interactions (NSI) of neutrinos with quarks affect quasi-elastic (QE) and resonant neutrino-nucleus scattering, with emphasis on axial couplings. It rewrites the NC hadronic current in the presence of NSI in terms of shifted nucleon form factors, identifies the isoscalar axial combination (epsilon^Au + epsilon^Ad) that enters through the octet form factor F_8^(A), and uses the GiBUU event generator to compute cross sections for argon targets. It also presents two new probes: reinterpretation of a future measurement of F_1^s ~ 0.01 as vector NSI, and a rough rescaling of the KamLAND g_s^A extraction to bound isoscalar axial NSI. The main quantitative results are the QE cross-section bands for representative NSI values, the conclusion that isoscalar axial NSI produces only excesses while isovector NSI can produce excesses or deficits, and the summary-level criterion that a >30% excess can be interpreted as isoscalar axial NSI.","tokens_in":23208,"tokens_out":10551,"duration_ms":92651,"significance":"If the cross-section results hold, the paper provides a useful framework for interpreting NC QE and resonance measurements in the presence of axial NSI: the form-factor replacement formulas (Eqs. 24-27) correctly reduce to the SM limit, and the identification of the isoscalar combination entering through F_8^(A) is an instructive observation. The use of an external event generator and the public availability of the modified code (github.com/dehpour/NC-NSI-GiBUU) are strengths. However, the two headline new probes are not yet quantitatively supported: the KamLAND bound rests on an explicitly oversimplified statistical scaling, and the 30% excess criterion uses a SM baseline without 2p-2h contributions. The paper is a useful contribution to the discussion but needs revision before the claims can be accepted at face value.","major_comments":[{"comment":"The summary states that 'an excess of more than 30% can be interpreted as axial isoscalar NSI' (Section VI), but the SM baseline in Figs. 2 and 3 is computed omitting 2p-2h excitations, as explicitly stated in Section V ('For the illustrative purposes, we omit the contribution from two particles-two holes (2p-2h) excitations'). Since 2p-2h processes are known to contribute at the tens-of-percent level to QE-like NC cross sections in argon at these energies, a measured excess over this baseline could arise from standard-model nuclear physics rather than NSI. The authors should either include 2p-2h in the baseline (they note GiBUU can do so, Ref. [46]) or explicitly quantify its shift on the bands before making the 30% diagnostic claim.","section":"Section V and Section VI"},{"comment":"The estimate that KamLAND can already constrain |epsilon^Au_tautau + epsilon^Ad_tautau| at the ~0.3 level is obtained by assuming the ±0.25 uncertainty in g_s^A from Ref. [37] is purely statistical, scaling it by 1/sqrt(N) assuming 1/4 of the events are nu_tau, and mapping the result linearly through Eqs. (26)-(27). The paper itself labels this 'of course an over-simplification.' Without a spectral fit and without separating statistical and systematic errors (flux, detector response, nuclear model), this rescaling does not constitute a quantitative bound. The abstract's statement that KamLAND data 'can already constrain' the tau axial NSI is therefore too strong; the authors should either provide a proper analysis or clearly present this as an order-of-magnitude illustration and soften the abstract and summary wording.","section":"Section IV.A"},{"comment":"The method for obtaining the QE cross-section bands relies on the factorization dsigma/dQ2|_{GiBUU} = alpha(Q2,E_nu) dsigma/dQ2|_{free} and on the assumption that alpha is independent of the form-factor variations. The only support is the statement that varying tilde F_A 'of order 1' changes alpha by less than 10%. For the isoscalar NSI case with epsilon = ±0.5, the relevant variation of tilde F_A includes the F_8^(A) term and is not obviously covered by the 'order 1' check; moreover, the 10% alpha variation itself is not shown. If alpha depends on the form factors at the level of 10%, the widths of the bands in Figs. 3 and 5 would be underestimated. Please document the alpha extraction more fully and test the independence over the actual range of tilde F_A and tilde F_i used in the figures.","section":"Section V, Eq. (34)"}],"minor_comments":[{"comment":"In the vector NSI discussion, the text refers to 'Eqs. (26, 27)' when giving the combinations 2 epsilon^Vu_mumu + epsilon^Vd_mumu and epsilon^Vu_mumu + 2 epsilon^Vd_mumu; these are the vector form-factor replacements and the correct references are Eqs. (24, 25).","section":"Section IV.A"},{"comment":"The statement 'For E_nu < 1 GeV, the oscillation length of nu_mu -> nu_tau is shorter than 350 km' is not correct over the whole range: with Delta m^2 ~ 2.5e-3 eV^2, L_osc ~ 2.48 E/Delta m^2 km, which gives about 992 km at E = 1 GeV and falls below 350 km only for E < 0.35 GeV. The flavor-composition estimate should be revised accordingly.","section":"Section IV.A"},{"comment":"The entry for g_s^A lists the value as '-0.15 +/- 0.09 Nominal'; the word 'Nominal' appears to be a typo for 'Nominal' or should be replaced by an explanation of the chosen central value and uncertainty band.","section":"Table I"},{"comment":"In the discussion of lepton-flavor-violating NSI, the text says 'epsilon^Au_alpha beta = -epsilon^Au_alpha beta|_{alpha != beta}'; one of the superscripts should be d, i.e., epsilon^Au_alpha beta = -epsilon^Ad_alpha beta.","section":"Section V"},{"comment":"The abstract contains 'E_nu < GeV' with a missing value; presumably it should read 'E_nu < 1 GeV' as in Section IV.A.","section":"Abstract"}],"recommendation":"major_revision","confidential_remarks":"The paper's central cross-section framework is interesting and the code availability is a plus, but the two new quantitative claims (KamLAND bound and the >30% excess diagnostic) are not yet supported at the level stated in the abstract and summary. Both can be addressed within the scope of the manuscript: include 2p-2h in the SM baseline or explicitly quantify its effect, and either perform a real KamLAND fit or clearly demote the bound to a qualitative illustration. The oscillation-length error in Section IV.A should also be corrected because it affects the flavor-composition estimate behind the KamLAND scaling."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Colleague,\n\nThe one thing to know: this is a genuinely useful paper on axial NC NSI, not a dud, but the headline diagnostic '>30% excess implies isoscalar axial NSI' is not as clean as the summary makes it sound. The 2p-2h omission in the GiBUU baseline is the reason.\n\nWhat's new: the paper works out how axial NSI enters QE and resonance NC scattering, including the isoscalar F_A^(8) form factor, which is usually dropped. The replacement formulas (24)-(27) are consistent with the SM limit and isospin relations, and the analysis showing that isovector axial NSI uncertainties cancel on argon while isoscalar ones do not is a real observation. The reinterpretation of KamLAND's g_s^A extraction as a bound on epsilon_tau tau^Au + epsilon_tau tau^Ad is new, and so is the point that a future F_1^s ~ 0.01 would be a vector-NSI signal. I also credit the public GiBUU modifications in the repo; that's reproducible work.\n\nSoft spots, in order. First, the 30% excess criterion. The SM baseline in Figs. 2 and 3 omits 2p-2h, and the text says so. At argon QE energies, 2p-2h is known to add tens of percent to the rate. A measured excess above that baseline therefore does not uniquely point to isoscalar axial NSI. This is a genuine overreach in the summary; the differential shape and the isovector deficit logic are less affected. Second, the KamLAND bound is a back-of-envelope scaling of ±0.25 uncertainty on g_s^A with 1/sqrt(N) and a 1/4 nu_tau fraction. The authors themselves call it 'of course an over-simplification.' It's an interesting suggestion, not a demonstrated constraint, so the abstract's 'can already constrain' should be read with that in mind. Third, the alpha(Q^2,E_nu) factorization of nuclear effects is tested at the 10% level only; the quoted cross-section bands inherit that systematic.\n\nThese are real but mostly acknowledged limitations. The central formalism is sound, the new probes are well motivated, and the paper is honest about most of its cuts. It deserves a serious referee, and a revision that either includes 2p-2h in the baseline or qualifies the 30% claim would substantially strengthen it. For anyone working on NSI phenomenology at DUNE, JUNO, or T2HK, this is worth reading. I'd bring it to the group.","headline":"Solid axial-NSI phenomenology with two genuinely new probes, but the headline '30% excess' criterion and the KamLAND bound are softer than they look.","tokens_in":23726,"tokens_out":2077,"would_cite":true,"duration_ms":18340,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"The paper argues that axial neutral-current non-standard interactions can produce >30% deviations in quasi-elastic neutrino-nucleus scattering that are separable from form-factor uncertainties, and that KamLAND atmospheric data may…","keywords":["non-standard interactions","neutral-current scattering","quasi-elastic neutrino scattering","axial form factors","strange form factor","neutrino-nucleus interactions","KamLAND atmospheric neutrinos","resonance scattering"],"falsifier":"A full spectral re-fit of the KamLAND atmospheric neutrino sample used in Ref. [37], with $(\\epsilon^{Au}_{\\tau\\tau}+\\epsilon^{Ad}_{\\tau\\tau})/2$ as a free parameter, settles the claimed O(0.3) bound: if the 95% allowed interval for the NSI combination remains wider than about 0.3 under that fit, the paper's scaling estimate is not a real constraint.","tokens_in":22709,"feed_emoji":"⚛️","tokens_out":13560,"duration_ms":111111,"temperature":0.7,"pith_summary":"The paper asks whether neutral-current non-standard interactions (NSI) of neutrinos with quarks, specifically the poorly constrained axial couplings, can be extracted from quasi-elastic and resonant neutrino-nucleus scattering rather than being buried in nucleon form-factor uncertainties. It argues that the isoscalar axial combination $(\\epsilon^{Au}_{\\tau\\tau}+\\epsilon^{Ad}_{\\tau\\tau})/2$, which can be of order one, dramatically changes the $\\nu_\\tau + N \\to \\nu_\\tau + N$ cross section, and that an excess above about 30% in the quasi-elastic neutral-current cross section off argon would be a clean signature of such isoscalar axial NSI. It also shows that isovector axial NSI can produce excesses or deficits up to about 30%, and that the $\\Delta$ resonance, which only feels isovector currents, can serve as a discriminator. On the extraction side, the paper argues that two existing or near-term probes, KamLAND atmospheric neutrinos used to determine $g_A^s$ and a future precision measurement of the vector strange form factor $F_1^s$, can already bound, or be misled by, these couplings. A sympathetic reader would care because these axial NSI parameters are among the least constrained new-physics couplings and could be probed by data that already exist.","feed_headline":"Axial NSI can shift neutrino cross sections by more than 30%","feed_subtitle":"In argon, an excess over 30% in quasi-elastic neutral-current scattering would single out isoscalar axial NSI.","key_machinery":"The central object is the NSI-shifted axial nucleon form factor $\\widetilde{F}_A^N$: in the quasi-elastic amplitude the axial current of the proton and neutron is replaced by combinations of the Standard Model axial form factor $F_A$, the strange axial form factor $F_A^s$, and the octet form factor $F_A^{(8)}$, with coefficients set by the axial NSI parameters $\\epsilon^{Au}_{\\alpha\\beta}$, $\\epsilon^{Ad}_{\\alpha\\beta}$, and $\\epsilon^{As}_{\\alpha\\beta}$. This object carries the argument because all quasi-elastic sensitivity to axial NSI is filtered through it, and because proton and neutron contributions to scattering off an almost-isoscalar nucleus like argon cancel for isovector NSI but add for isoscalar NSI, which is why the two cases have different signatures and different form-factor-error sensitivities. The companion machinery is the nuclear-correction factor $\\alpha(Q^2,E_\\nu)$, defined as the ratio of the nuclear cross section to the free-nucleon cross section and treated as independent of the axial form factors, which lets cross-section shifts computed for free nucleons be carried over to scattering off argon.","core_discovery":"The paper's central claim is that axial neutral-current NSI leave a recognizable imprint in neutrino-nucleus scattering once form-factor information from lattice QCD, charged-lepton scattering, and $\\beta$ decay is used as independent input. In the quasi-elastic channel, every axial NSI coupling enters through redefined axial form factors $\\widetilde{F}_A^p$ and $\\widetilde{F}_A^n$; the isoscalar combination $\\epsilon^{Au}_{\\alpha\\alpha}+\\epsilon^{Ad}_{\\alpha\\alpha}$ brings in the octet form factor $F_A^{(8)}$, whose lattice value is used as input. The paper finds that for argon an isoscalar axial NSI at the present O(1) bounds produces an excess in the quasi-elastic neutral-current cross section that can exceed 30%, while the allowed isovector axial NSI can at most produce roughly a 30% excess or deficit; hence a >30% excess singles out isoscalar axial NSI. Because the $\\Delta$ resonance current is purely isovector, the $\\nu+N\\to\\nu+\\Delta$ reaction is blind to isoscalar axial NSI and can break the remaining ambiguity. The paper also claims that the KamLAND atmospheric sample already constrains $\\epsilon^{Au}_{\\tau\\tau}+\\epsilon^{Ad}_{\\tau\\tau}$ at about 0.3, and that a future $\\nu_\\mu$ quasi-elastic measurement returning $F_1^s\\sim 0.01$ would be a sign of vector NSI couplings $\\epsilon^{Vu}_{\\mu\\mu}$ or $\\epsilon^{Vd}_{\\mu\\mu}$ near 0.01 rather than genuine strangeness.","pith_inferences":["Editorial extension: the argon cancellation that suppresses sensitivity to $g_s^A$ and $\\epsilon^{As}$ relies on $Z \\simeq A/2$, so a target with visible neutron excess or a free-proton target should lift the cancellation and give a cleaner probe of the strange-axial and isoscalar-axial combinations than the argon curves alone.","Editorial extension: the claimed KamLAND bound could be checked without new data by re-fitting the published atmospheric sample with $(\\epsilon^{Au}_{\\tau\\tau}+\\epsilon^{Ad}_{\\tau\\tau})/2$ as a free parameter; a full spectral fit would either confirm the 0.3-level bound or reveal that the paper's scaling estimate was optimistic.","Editorial extension: because isoscalar axial NSI produces only an excess while isovector axial NSI can produce either sign, the sign and size of a single high-statistics deviation divides the possible new-physics parameter space into disjoint regions, providing a quick model-discrimination rule for future exposures."],"forward_implications":["A quasi-elastic neutral-current cross-section measurement off argon at a long-baseline detector that finds an excess above about 30% over the Standard Model would be evidence for isoscalar axial NSI rather than a form-factor artifact.","An observed deficit in the same channel must stay below about 30% if it is to be explained by axial NSI; a larger deficit requires new physics beyond these couplings.","The $\\Delta$ resonance channel can act as a control: isoscalar axial NSI leave it unaffected, so a large quasi-elastic excess with no corresponding shift in the resonance channel selects the isoscalar interpretation.","A future precise $\\nu_\\mu$ neutral-current quasi-elastic measurement returning $F_1^s \\sim 0.01$ would indicate $\\epsilon^{Vu}_{\\mu\\mu}$ and/or $\\epsilon^{Vd}_{\\mu\\mu}$ at the $10^{-2}$ level, close to existing oscillation and coherent-scattering bounds.","A re-analysis of KamLAND atmospheric neutrino data with $E_\\nu < 1$ GeV could set a bound $|\\epsilon^{Au}_{\\tau\\tau}+\\epsilon^{Ad}_{\\tau\\tau}| \\lesssim 0.3$, stronger than current limits on that combination."],"supporting_citations":[{"why":"Supplies the published $g_s^A=-0.14\\pm0.25$ from KamLAND atmospheric neutrinos; scaling its uncertainty to the one-quarter $\\nu_\\tau$ sub-sample yields the paper's headline NSI bound.","marker":"[37]"},{"why":"Provides the lattice-QCD values of $g_A^{(8)}$, $M_A^{(8)}$, and $F_A^{(8)}(Q^2)$ needed to predict how isoscalar axial NSI shifts the quasi-elastic cross section.","marker":"[20]"},{"why":"Sets out the current global bounds and the SNO-based constraints on $\\epsilon^{Au}-\\epsilon^{Ad}$, defining which axial NSI combinations are still allowed and the $J^\\mu_{\\rm had}\\to-J^\\mu_{\\rm had}$ degeneracy.","marker":"[8]"},{"why":"Gives the toy model with $\\epsilon^{Au}_{\\tau\\tau}=\\epsilon^{Ad}_{\\tau\\tau}\\sim1$ that motivates treating O(1) isoscalar axial tau NSI as a live possibility.","marker":"[10]"},{"why":"The nuclear event generator that accounts for nuclear medium effects in the argon cross-section computation; the paper modifies it to include neutral-current NSI.","marker":"[42]"},{"why":"MiniBooNE-based analysis constraining $F_1^s(Q^2)$, the comparison level against which a future $F_1^s\\sim0.01$ signal would be read as vector NSI.","marker":"[25]"},{"why":"Extraction of the axial mass $M_A$ used as an input parameter whose uncertainty contributes to the quasi-elastic cross-section error bands.","marker":"[29]"},{"why":"The authors' earlier far-detector analysis of neutral-current deep inelastic scattering, which motivates the flavor-mixing treatment used for mixed neutrino fluxes.","marker":"[9]"}],"fun_headline_variants":["Axial NSI leaves >30% excess in argon QE NC scattering","Isoscalar axial NSI uniquely flagged by argon rate excess","KamLAND already bounds tau axial NSI from atmospheric data","Vector NSI could mimic strange form factor in nu-mu scattering","Resonance channel breaks ambiguity left by QE for axial NSI"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The estimate that KamLAND can already bound $\\epsilon^{Au}_{\\tau\\tau}+\\epsilon^{Ad}_{\\tau\\tau}$ at about 0.3 rests on assuming the published $g_s^A$ uncertainty is purely statistical, scales as $1/\\sqrt{N}$ when only about a quarter of the events are $\\nu_\\tau$, and maps linearly onto the NSI combination; the paper itself labels this an over-simplification.","fun_headline_variants_meta":{"raw":{"variants":["Axial NSI leaves >30% excess in argon QE NC scattering","Isoscalar axial NSI uniquely flagged by argon rate excess","KamLAND already bounds tau axial NSI from atmospheric data","Vector NSI could mimic strange form factor in nu-mu scattering","Resonance channel breaks ambiguity left by QE for axial NSI"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000686,"raw_usage":{"total_tokens":3235,"prompt_tokens":1197,"completion_tokens":2038,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":813,"completion_tokens_details":{"reasoning_tokens":1946}},"tokens_in":813,"tokens_out":2038,"duration_ms":13730,"temperature":1.0,"reasoning_tokens":1946,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-11T13:13:54.917610+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A full spectral re-fit of the KamLAND atmospheric neutrino sample used in Ref. [37], with $(\\epsilon^{Au}_{\\tau\\tau}+\\epsilon^{Ad}_{\\tau\\tau})/2$ as a free parameter, settles the claimed O(0.3) bound: if the 95% allowed interval for the NSI combination remains wider than about 0.3 under that fit, the paper's scaling estimate is not a real constraint.","supporting_citations":[{"cited_title":"Intermediate-Energy Semileptonic Probes of the Hadronic Neutral Current","cited_arxiv_id":"nucl-th/9307022","evidence_quote":"Supplies the published $g_s^A=-0.14\\pm0.25$ from KamLAND atmospheric neutrinos; scaling its uncertainty to the one-quarter $\\nu_\\tau$ sub-sample yields the paper's headline NSI bound."}],"review_version":1}