{"id":"ed2b23e3-3289-4e5f-b21c-f45ed3bddfa4","arxiv_id":"2411.16784","paper_version":3,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":2,"one_line_summary":"Lattice QCD on the PACS10 superfine ensemble yields nucleon axial, induced pseudoscalar, and pion-nucleon couplings consistent with experiment and prior lattice results, with no strong lattice-spacing dependence.","lead":"Using supercomputer simulations of quarks and gluons on a very fine grid, the PACS Collaboration measured three quantities that control how protons and neutrons interact weakly with neutrinos. Their results agree with experiment and with other simulations, but the finest-grid results are still preliminary.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The g*_P and g_piNN results rest entirely on the unreleased time-derivative method in Ref. [21]; 'complete removal' of the leading piN contamination is asserted in Sec. 4.2 but never derived or validated here.","rationale":"Good-faith reading: this is a proceedings report from PACS; the main new data are the superfine (256^4, a=0.04 fm) results, and the headline is that the F_P problem is solved by a new time-derivative correlator. What has to be true for the central claim to hold: (i) the method of Ref. [21] actually removes the leading piN contamination; (ii) the residual systematic from the method and from Z_A is under control; (iii) the lattice-spacing dependence is small enough at three points. The weakest condition is (i), because the paper presents no derivation or cross-check. The reader's weakest_assumption is the same. I give credit: the paper labels the superfine results preliminary, shows only statistical errors for them, and explicitly says continuum extrapolation is future work; the coarse and fine results have been published in Refs. [19,20] with systematics. But those published works do not establish the new method [21]. One might counter that a proceedings is allowed to cite an in-preparation method paper; however, the claim of 'complete removal' is not a standard analysis choice and the numerical output depends on it. The secondary concern about transferring Z_A from Ref. [20] to the new ensemble is real but less load-bearing, since it would affect all three couplings coherently and the paper compares with experiment. Verdict: CONDITIONAL is right; my concern does not change the reader's verdict, so UNCHANGED. The proposed re-analysis would settle it.","tokens_in":8870,"tokens_out":5035,"duration_ms":58178,"concrete_test":"Re-analyze the same F_P three-point data from the 160^4 and 256^4 ensembles with a standard two-state fit that includes the leading piN excited state explicitly (as in Refs. [18,20]), and compare the resulting z-expansion values of g*_P and g_piNN with the time-derivative-method values. Agreement within combined statistical errors would validate the removal; any significant disagreement, or a residual t_sep slope in the time-derivative F_P values at fixed q^2, would show the removal is not complete.","verdict_should_be":"UNCHANGED","load_bearing_attack":"Section 4.2 and the Summary make a strong version of the central claim: after 'careful tuning of the smearing parameters', the new time-derivative correlator method of Ref. [21] 'completely remov[es] the leading piN contribution from the analysis of the F_P data', and the resulting g*_P and g_piNN are accurate and show no strong lattice-spacing dependence. This is the load-bearing step for the two pseudoscalar couplings: F_P is the only input to the z-expansion that produces them, and any residual piN contamination enters g*_P and g_piNN directly. The paper does not describe the method, derive the removal, or show a validation on synthetic or cross-check data; Ref. [21] is cited only as 'in preparation'. The word 'completely' requires more than a shift in the effective plateau: it requires that the derivative procedure eliminates the entire leading excited-state term. The paper is not internally inconsistent, and it is honest about being preliminary, but as written the central numerical result for F_P cannot be independently checked. The superfine points carry only statistical errors and the continuum extrapolation is explicitly not performed, so the 'no strong lattice-spacing dependence' conclusion also rests partly on this unvalidated method.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This manuscript reports lattice QCD calculations of the isovector nucleon axial-vector coupling g_A, the induced pseudoscalar coupling g*_P, and the pion-nucleon coupling g_piNN using PACS10 ensembles at three lattice spacings (0.09, 0.06, 0.04 fm) with a physical pion mass and a spatial extent of about 10 fm. The axial form factor is extracted with a plateau method, while the induced pseudoscalar form factor F_P is analyzed with a z-expansion including the pion-pole factor, using a new time-derivative correlator method (Ref. [21], in preparation) that is claimed to completely remove the leading piN excited-state contamination. Results for the three couplings are compared with experimental values and with other lattice QCD determinations. The superfine results are explicitly labeled preliminary and are shown with statistical errors only; no continuum extrapolation is performed.","tokens_in":42,"tokens_out":5981,"duration_ms":111867,"significance":"If the new F_P method performs as claimed, the paper would demonstrate that the long-standing piN excited-state contamination problem for the induced pseudoscalar form factor can be overcome at the physical point, and the observed consistency across three lattice spacings would support the prospect of a controlled continuum extrapolation of g_A, g*_P, and g_piNN. The work has notable strengths: physical-point ensembles with large volume, the use of AMA, nonperturbative O(a) improvement, Schrödinger functional renormalization, and comparison with multiple independent lattice and experimental determinations. The central caveat is that the decisive F_P technique is not documented or validated in this manuscript, so the two pseudoscalar couplings currently cannot be independently checked by the reader. The paper is internally consistent and appropriately hedged about the preliminary nature of the superfine results.","major_comments":[{"comment":"The claim that the new time-derivative correlator method (Ref. [21], 'in preparation') completely removes the leading piN contribution from the F_P data is the load-bearing step for the g*_P and g_piNN results. The manuscript gives no derivation, algorithmic description, or validation of this method, and no estimate of the residual contamination after the removal. Since F_P(q^2) is the sole input to the z-expansion that determines g*_P and g_piNN, any residual piN contamination biases these couplings directly. The authors should either include the method and demonstrate its effectiveness (for example on synthetic correlators with known piN contamination, or by a comparison with an independent extraction technique), or replace 'completely removes' with a quantitatively bounded residual-estimate statement. As written, the two pseudoscalar couplings cannot be independently assessed by the reader.","section":"Section 4.2 and Summary (Ref. [21])"},{"comment":"The renormalization constants Z_A and Z_V are said to be determined by the Schrödinger functional method, with a pointer to Appendix E of Ref. [20]. It is not stated whether the Z_A value used for the new superfine (beta=2.20) ensemble was computed directly at beta=2.20, interpolated from lower beta, or assumed unchanged, nor how the associated uncertainty is propagated. Because the reported g_A is proportional to Z_A, this point must be documented before the g_A agreement with experiment can be evaluated. Please report the Z_A values and their scale/beta dependence explicitly.","section":"Section 3 (renormalization)"},{"comment":"The statement that 'no strong dependence on the lattice spacing is observed' for the three couplings is not supported by a controlled continuum extrapolation. The superfine results in Fig. 2 carry only statistical errors, are shown at two separate tsep values without a combined analysis, and no correlated fit in the lattice spacing is performed. The text is mostly careful in calling the results preliminary, but the Summary phrase 'there is no strong dependence on the lattice spacing in our results' should be qualified to say that this is a qualitative consistency check within current large uncertainties, not an established continuum behavior.","section":"Section 4.2 and Summary (lattice-spacing dependence)"}],"minor_comments":[{"comment":"The phrase 'Combining the results obtained from the all of our coarse, fine and superfine lattices' is ungrammatical and overstates the analysis, since no combined fit is actually presented; please rephrase to refer to a comparison of results from the three ensembles.","section":"Abstract"},{"comment":"The caption says 'Two open triangle symbols represent the preliminary results... with tsep = 0.8 fm (the upper value...) and tsep = 1.2 fm (the lower value...)', but it is not immediately clear in the figure which symbol corresponds to which tsep; please add explicit labels to the figure.","section":"Figure 2 caption"},{"comment":"The z-expansion fit used for F_P is not specified in terms of truncation order, number of coefficients, priors, or treatment of correlations; a sentence giving these details or an explicit pointer to the exact implementation in Ref. [20] would improve reproducibility.","section":"Section 4.2"},{"comment":"Since the new time-derivative correlator method is central to the paper, please add a footnote or short appendix outlining its key idea even if the full derivation is deferred to Ref. [21].","section":"Section 2"},{"comment":"The phrase 'Needless to say' is informal for a journal article and should be replaced with a more neutral formulation.","section":"Section 5"},{"comment":"Reference [9] appears to cite a preprint from 2016; please check whether a published version is available and update the citation if so.","section":"References"}],"recommendation":"major_revision","confidential_remarks":"The decisive technique for the pseudoscalar couplings is contained in a companion paper that is still in preparation. If the venue treats this as a proceedings-style contribution where a forward reference to an upcoming paper is acceptable, a minor revision might be considered; for a regular journal article, the missing method description and validation (or a strong quantitative caveat) is a substantive gap. I see no indication of circular reasoning or internal inconsistency, and the authors are transparent that the superfine results are preliminary. The paper is likely publishable after the requested revisions."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Short version: this is a normal LATTICE proceedings from the PACS Collaboration, and the genuinely new item is the superfine (a=0.04 fm, 256^4) data for the three nucleon isovector couplings. The g_A part is standard and credible. The two pseudoscalar couplings, g*_P and g_piNN, depend on a new time-derivative correlator method that is only cited as 'in preparation' (Ref. [21]) and is neither described nor validated here. That is the whole ballgame for those two numbers.\n\nWhat the paper does well: it is honest about its status. The superfine points are labeled preliminary, carry statistical errors only, and the text explicitly says no continuum extrapolation has been performed. The dispersion-relation check is a sensible sanity test, and the three ensembles at physical pion mass on a 10 fm box give a useful look at spacing dependence within one framework. The z-expansion with pion-pole factor is standard. The plots comparing against experiment and other collaborations are useful.\n\nThe soft spot is exactly what the stress-test note flags. F_P is the only input for g*_P and g_piNN, and the claim in Sec. 4.2 that the new method 'completely remov[es] the leading piN contribution' is a strong assertion. The reader cannot check it from this proceedings. The word 'completely' is doing real work; a shift in the plateau does not by itself prove the whole excited-state term is gone. I do not see internal inconsistency or circularity, but I do see an unreleased method carrying the central result. A smaller, distinct concern is that the Schrödinger functional Z_A from Ref. [20] is transferred to the new ensemble without discussion; that may be fine at these settings, but it is an assumption. And with only two t_sep values for the superfine lattice, the 'no strong lattice spacing dependence' statement is a preliminary observation, not a conclusion.\n\nBottom line: this is a progress report for lattice practitioners and anyone tracking the status of g_A, g*_P, and g_piNN from lattice QCD. It deserves a serious referee, because the superfine data point is new and the method, if it works, would be important. But the referee should put the burden on the authors: either the method paper is available for scrutiny, or the F_P results stay provisional. For a proceedings this may be acceptable; for a full journal article it would not be. My recommendation: engage with it, but do not treat g*_P and g_piNN as established until Ref. [21] is public.","headline":"New superfine PACS10 data are a genuine step, but the g*_P and g_piNN results rest on an unshown 'complete removal' of piN contamination, so treat this as a progress report, not a definitive calculation.","tokens_in":9727,"tokens_out":4472,"would_cite":false,"duration_ms":38826,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["12.38.Gc","14.20.Dh"],"model":"deepseek-v4-flash","headline":"The paper claims that a time-derivative correlator method removes the leading pion-nucleon contamination from the induced pseudoscalar form factor, and that on the PACS10 superfine lattice the nucleon axial-vector, induced pseudoscalar…","keywords":["lattice QCD","nucleon axial-vector coupling","induced pseudoscalar coupling","pion-nucleon coupling","PACS10 ensembles","excited-state contamination","time-derivative correlator method","physical point"],"falsifier":"Apply the time-derivative correlator method to $F_P$ on the superfine ensemble at several source-sink separations beyond the current $t_{\\mathrm{sep}}/a = 20, 29$ and check whether $g_P^*$ and $g_{\\pi NN}$ stay constant; a visible drift with $t_{\\mathrm{sep}}$, or an analysis with a variational basis that disagrees with the new-method result, would show that the leading $\\pi N$ contribution was not completely removed.","tokens_in":8640,"feed_emoji":"⚛️","tokens_out":12421,"duration_ms":104700,"temperature":0.7,"pith_summary":"This paper is a lattice QCD determination of three couplings that control the weak axial structure of the nucleon: the axial-vector coupling $g_A$, the induced pseudoscalar coupling $g_P^*$, and the pion-nucleon coupling $g_{\\pi NN}$. The authors use the PACS10 ensembles at three lattice spacings (0.09, 0.06, and 0.04 fm) on a volume with large spatial extent of about 10 fm and physical quark masses, and they report that all three couplings are consistent across spacings and agree with experiment and with other lattice QCD results. The central technical claim is that a newly proposed time-derivative correlator method completely removes the leading pion-nucleon excited-state contamination from the induced pseudoscalar form factor $F_P$, which has long blocked accurate values of $g_P^*$ and $g_{\\pi NN}$. The results for the superfine lattice are explicitly preliminary, and no continuum extrapolation is attempted; instead the paper argues that the absence of strong lattice-spacing dependence makes the three-spacing comparison a controlled start toward one. If the claim holds, precision lattice values of these couplings could feed neutrino oscillation experiments and the neutron lifetime puzzle.","feed_headline":"Three nucleon couplings reproduce experiment on superfine lattice","feed_subtitle":"Axial-vector, induced pseudoscalar and pion-nucleon couplings agree with experiment across three lattice spacings.","key_machinery":"The load-bearing object is the time-derivative correlator method for $F_P$ (Ref. [21], in preparation), a correlator-based technique the paper says removes the leading pion-nucleon excited-state contribution once the exponential smearing parameters are tuned; the paper does not derive it, so the method itself carries the $g_P^*$ and $g_{\\pi NN}$ results. Around it stand the PACS10 ensembles with the six stout-smeared $O(a)$-improved Wilson-clover quark action and Iwasaki gauge action at $\\beta=1.82$, $2.00$, $2.20$; all-mode averaging for statistics; the Schr\\\"odinger functional renormalization factor $Z_A$; and the $z$-expansion parametrization of $(q^2+m_\\pi^2)F_P(q^2)$, which factors out the pion pole before the couplings are read off.","core_discovery":"On the PACS10 ensembles, the authors compute the nucleon two- and three-point functions with exponentially smeared interpolating operators and all-mode averaging, extract $g_A$ from the axial form factor at zero momentum transfer, and extract $g_P^*$ and $g_{\\pi NN}$ from $F_P(q^2)$ at seven momentum transfers using a $z$-expansion of $(q^2+m_\\pi^2)F_P(q^2)$ that factors out the pion pole. Their main stated result is that, with careful tuning of the smearing parameters, the new time-derivative correlator method (Ref. [21], in preparation) 'completely removes the leading $\\pi N$ contribution' from the $F_P$ analysis, so that the two pseudoscalar couplings can be determined accurately. At the three lattice spacings the nucleon dispersion relation deviates from the continuum relation by at most 1.1%, and the three couplings show no strong dependence on the lattice spacing; $g_A$, $g_P^*$, and $g_{\\pi NN}$ agree with the experimental values and with other lattice QCD results within the quoted uncertainties. The superfine data are still preliminary, so the paper stops short of a continuum extrapolation.","pith_inferences":["If the time-derivative method really removes all leading $\\pi N$ contamination, the same idea could be applied to other nucleon matrix elements (scalar, tensor, vector) whose plateaus suffer from excited-state contamination; the paper does not discuss this extension.","Because the decisive method is cited as 'in preparation' and is not validated here, the stability of the $g_P^*$ and $g_{\\pi NN}$ results cannot be independently checked until Ref. [21] appears; that single reference is the fastest possible falsifier.","The apparent absence of lattice-spacing dependence between 0.09 and 0.04 fm suggests the remaining discretization errors are below the statistical noise; if so, adding statistics on the superfine lattice will matter more than further action improvement.","A simple testable consequence is that the new method should make the $F_P$ plateau strictly independent of the source-sink separation; any residual $t_{\\mathrm{sep}}$ drift would indicate the leading contamination is suppressed rather than completely removed."],"forward_implications":["A controlled continuum extrapolation of $g_A$, $g_P^*$, and $g_{\\pi NN}$ becomes a statistics-limited exercise on the existing coarse, fine, and superfine ensembles rather than a search for new analysis methods.","The two least well-known axial couplings, $g_P^*$ and $g_{\\pi NN}$, can be produced at physical quark mass with the leading excited-state contamination under control, removing a known source of lattice systematic error.","Reliable values of these couplings can be used as inputs to neutrino-nucleus cross-section calculations for long-baseline oscillation experiments, where the axial form factor is a significant uncertainty.","The $g_A$ result at all three spacings serves as a benchmark that the same ensembles and analysis reproduce a well-measured experimental quantity, supporting the credibility of the less well-known pseudoscalar results.","Combining the three spacings with proper systematic errors should allow a continuum limit with controlled discretization uncertainty, since the observed spacing dependence is already smaller than current statistical errors."],"supporting_citations":[{"why":"Supplies the experimental value of $g_A = 1.2756(13)$ that the lattice results are compared against.","marker":"[7]"},{"why":"Supplies the muon-capture experimental value used to benchmark $g_P^*$.","marker":"[8]"},{"why":"One of the two pion-nucleon scattering analyses used for the experimental isospin-averaged $g_{\\pi NN}$.","marker":"[9]"},{"why":"The other pion-nucleon scattering analysis entering the experimental isospin average for $g_{\\pi NN}$.","marker":"[10]"},{"why":"The lattice QCD review that collects the other lattice results and provides the comparison values.","marker":"[11]"},{"why":"Earlier PACS result for the axial-vector coupling that anchors the coarse-lattice comparison and systematic error treatment.","marker":"[14]"},{"why":"Earlier PACS coarse-lattice computation whose results are compared with the fine and superfine data to expose lattice-spacing effects.","marker":"[19]"},{"why":"PACS fine-lattice paper that supplies the notation, Schr\\\"odinger functional $Z_A$, the $z$-expansion prescription, and the systematic error treatment used throughout.","marker":"[20]"},{"why":"In-preparation companion paper describing the time-derivative correlator method that the claim of complete removal of leading $\\pi N$ contamination depends on.","marker":"[21]"},{"why":"Introduces the $z$-expansion used to parameterize $(q^2+m_\\pi^2)F_P(q^2)$ without model assumptions.","marker":"[22]"}],"fun_headline_variants":["Nucleon couplings match experiment on 10 fm lattice","Three nucleon couplings agree with experiment","PACS10 lattice: gA, gP*, gPiNN match data","Superfine lattice reproduces nucleon weak couplings","10-fm quark grid captures axial and pion couplings"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The load-bearing premise is that the unpublished time-derivative correlator method removes the entire leading pion-nucleon excited-state contamination from the $F_P$ data, rather than merely reducing it, so that the residual time dependence is negligible.","fun_headline_variants_meta":{"raw":{"variants":["Nucleon couplings match experiment on 10 fm lattice","Three nucleon couplings agree with experiment","PACS10 lattice: gA, gP*, gPiNN match data","Superfine lattice reproduces nucleon weak couplings","10-fm quark grid captures axial and pion couplings"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000372,"raw_usage":{"total_tokens":2020,"prompt_tokens":1005,"completion_tokens":1015,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":621,"completion_tokens_details":{"reasoning_tokens":936}},"tokens_in":621,"tokens_out":1015,"duration_ms":7460,"temperature":1.0,"reasoning_tokens":936,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-12T13:27:06.450118+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Apply the time-derivative correlator method to $F_P$ on the superfine ensemble at several source-sink separations beyond the current $t_{\\mathrm{sep}}/a = 20, 29$ and check whether $g_P^*$ and $g_{\\pi NN}$ stay constant; a visible drift with $t_{\\mathrm{sep}}$, or an analysis with a variational basis that disagrees with the new-method result, would show that the leading $\\pi N$ contribution was not completely removed.","supporting_citations":[{"cited_title":"Measurement of the Formation Rate of Muonic Hydrogen Molecules","cited_arxiv_id":"1502.00913","evidence_quote":"Supplies the muon-capture experimental value used to benchmark $g_P^*$."},{"cited_title":"Study of the Pion-Nucleon Coupling Constant Charge Dependence on the Basis of the Low-Energy Data on Nucleon-Nucleon Interaction","cited_arxiv_id":"1604.02912","evidence_quote":"One of the two pion-nucleon scattering analyses used for the experimental isospin-averaged $g_{\\pi NN}$."},{"cited_title":"Limkaisang, K","cited_arxiv_id":null,"evidence_quote":"The other pion-nucleon scattering analysis entering the experimental isospin average for $g_{\\pi NN}$."},{"cited_title":"Yamazaki (PACS) (2024), in preparation","cited_arxiv_id":null,"evidence_quote":"In-preparation companion paper describing the time-derivative correlator method that the claim of complete removal of leading $\\pi N$ contamination depends on."}],"review_version":1}