{"id":"8f605328-7180-45b9-94fd-b9139851073f","arxiv_id":"2512.20454","paper_version":3,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"Adding the quark-mass-dependent F2 three-nucleon force does not improve ab initio medium-mass predictions; its main effect is to shift short-range couplings rather than add new physics.","lead":"Adding a newly predicted quark-mass-dependent three-nucleon force, F2, to ab initio nuclear calculations does not systematically improve predicted energies and radii of medium-mass nuclei. The main effect of F2 is to shift other fitted short-range couplings, so the study finds no evidence to promote F2 to lower order in Weinberg power counting.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"F2 no-promotion conclusion depends on dimensional regularization; under spectral-function regularization the counterterm structure changes, so the empirical null result may not transfer to Weinberg power counting.","rationale":"The reader identified dimensional regularization as the weakest assumption, and this is the most load-bearing issue for the central claim. The paper's empirical null result is obtained entirely within DR, but the Weinberg power-counting question is about the renormalized interaction; if the counterterm structure changes under a more physical regularization, the fitted cD/cE and the apparent smallness of the direct F2 contribution may change. The authors explicitly acknowledge this in Sec. I, which is why I do not call it an overlooked flaw, but it still limits the strength of the Sec. V conclusion. The convergence issue is secondary: without quantified many-body truncation errors, the null result is less definitive, but the central claim is already phrased as 'no direct evidence' rather than a rigorous exclusion. Overall, the paper is careful and internally consistent in its numerical execution, so I would not change the reader's CONDITIONAL verdict; the conditional status is exactly what the regulator dependence warrants.","tokens_in":9910,"tokens_out":9094,"duration_ms":101397,"concrete_test":"Recompute the F2 interaction matrix elements and repeat both fitting strategies (GT and 16O) using spectral-function regularization with a cutoff around 450–500 MeV, adding the counterterms identified by Cirigliano et al. [28]. Compare the resulting cD, cE, ground-state energies and charge radii for 16O, 40Ca, and 48Ca with the dimensional-regularization results. If the differences exceed the estimated IMSRG truncation error, the no-promotion conclusion should be restricted to DR; if they agree within uncertainties, the conclusion is robust.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central Sec. V conclusion — no direct evidence justifying promotion of F2 in Weinberg power counting — is conditional on a regulator choice that the authors themselves flag in Sec. I: with spectral-function regularization the F2 term shows a linear cutoff divergence, so related short-range 3N couplings would need to be promoted as counterterms, whereas all calculations here use dimensional regularization. Promotion decisions in an EFT should be regulator-independent statements about the renormalized theory. If the physical regulator introduces additional counterterms that mix with cD and cE, then the fitted LEC values and the apparent 'reparametrization' of F2 could be DR artifacts. The paper's own Fig. 4 shows a non-negligible direct F2 expectation value in 3H, so the later statement that 'the contributions of the new F2 interaction itself always remain small' is not uniformly supported; what remains small may be specific to the DR scheme and to the observables studied. The authors are appropriately cautious in the introduction, but the Sec. V claim is stated without carrying this caveat, and the cited [29] support is an independent preprint rather than a settled result.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper investigates the impact of the quark-mass-dependent three-nucleon (3N) interaction characterized by the coupling F2 on the ground-state energies and charge radii of medium-mass nuclei. The authors combine the EMN 450 chiral NN interaction at N2LO and N3LO with established 3N forces and the new F2 term, using both bare and SRG-evolved interactions. Two fitting strategies are explored: one constrained by the 3H half-life and one additionally by the 16O ground-state energy and charge radius. Many-body calculations are performed with IMSRG(2) and Hartree-Fock decompositions are used to isolate the F2 contribution. The main conclusion is that F2 mainly acts by changing the short-range 3N couplings cD and cE during refitting, while the direct F2 contribution remains small for medium-mass nuclei; the authors find no systematic improvement from including F2 and therefore no direct evidence to promote F2 to lower order in Weinberg power counting.","tokens_in":10220,"tokens_out":4113,"duration_ms":40152,"significance":"If the no-promotion conclusion is robust, this is a valuable negative result for chiral EFT: it would redirect attention away from premature promotion of the quark-mass-dependent F2 force in Weinberg power counting. The paper is technically sound in its internal logic: the Hartree-Fock decomposition cleanly isolates the F2 effect, two complementary fit strategies are used, and the results are tested across a wide range of doubly closed-shell nuclei. The use of public many-body codes and explicit LEC fits adds to reproducibility. However, the central claim is weakened by the acknowledged regulator dependence of the F2 interaction and by the absence of convergence or truncation-error quantification, so the significance is conditional on these gaps being addressed.","major_comments":[{"comment":"The no-promotion conclusion is stated for Weinberg power counting, but all calculations use dimensional regularization. The authors themselves note in Sec. I that with spectral-function regularization the F2 term shows a linear cutoff divergence and related short-range 3N couplings would need to be promoted as counterterms [28]. Since promotion decisions in an EFT should be regulator-independent statements about the renormalized theory, the empirical null result presented here does not, by itself, constrain Weinberg power counting. Either the conclusion should be explicitly restricted to 'within the dimensional-regularization-based framework used here', or a regulator-variation analysis should be provided to show that the conclusion is not an artifact of DR.","section":"Sec. V and Sec. I"},{"comment":"No convergence checks or chiral-truncation uncertainties are shown. The IMSRG(2) calculations use a fixed basis e_max=14, E3max=24, and a single harmonic oscillator frequency (omega=16 MeV for most nuclei, 12 MeV for 120,132Sn). The differences between the F2=0 and F2=0.05 results in Figs. 5 and 6 are at the 1-2% level, but without an estimate of the many-body truncation error or the chiral truncation uncertainty it is not possible to determine whether the observed deviations from experiment are significant. Please add e_max/E3max convergence checks for at least one representative nucleus and estimate the truncation uncertainty before concluding that F2 does not improve the description of medium-mass nuclei.","section":"Sec. II and Sec. IV"},{"comment":"The 16O fit strategy uses cD=5.0 for the evolved interactions, but the text states that the cD value is only loosely constrained and that all blue points for F2=0.05 reproduce the experimental 16O observables within chiral uncertainties. The medium-mass results in Fig. 6 use this single cD value, so the conclusion that F2 mainly acts by shifting the short-range couplings may be sensitive to the arbitrarily chosen cD. Please propagate the cD uncertainty from the 16O fit to the medium-mass observables, or at least show the sensitivity of the conclusions to the cD range.","section":"Sec. III B and Sec. IV"},{"comment":"There is an internal inconsistency in the characterization of F2 contributions. Section III C states that the expectation value of the F2 interaction 'for light systems can be significant', while Sec. V concludes that 'the contributions of the new F2 interaction itself always remain small'. This is not necessarily a logical contradiction if 'small' is meant only for medium-mass nuclei, but the wording is misleading. More importantly, Fig. 4 shows a non-negligible F2 expectation value in 3H (around 0.5 MeV for the refitted interaction), so the supporting claim that F2 contributions are always small is not uniformly supported by the paper's own results. Please clarify the statement and distinguish the direct F2 contribution in light systems from that in medium-mass nuclei.","section":"Sec. III C and Sec. V"}],"minor_comments":[{"comment":"The use of ħω=12 MeV for 120,132Sn is mentioned only in the figure caption; give a brief justification in the text and state the oscillator frequency used for the other nuclei.","section":"Sec. II or Fig. 6 caption"},{"comment":"The caption states that E3max=16 is used for the Hartree-Fock calculations of 16O, whereas E3max=24 is used for the IMSRG(2) calculations. Clarify whether this difference affects the comparison of the HF decomposition with the full results.","section":"Fig. 4 caption"},{"comment":"The N3LO rows list F2=0.15 for the bare interaction and F2=0.05 for the evolved interaction, but the text in Sec. III B states that the optimal bare F2 is 0.15 and the evolved F2 is 0.05. This is consistent, but the table would benefit from a column or note indicating which entries are 'bare' and which are 'evolved' to avoid confusion.","section":"Table I"},{"comment":"Reference [28] is cited as 'private communication' but is used to support a load-bearing caveat about the spectral-function-regularization divergence. If this result is publicly available in a preprint or proceedings, please cite that version; otherwise include the derivation in an appendix.","section":"Ref. [28]"}],"recommendation":"major_revision","confidential_remarks":"The paper addresses an important question and the internal calculations appear consistent. The main issue is that the central no-promotion conclusion is stated more strongly than the evidence supports, given the acknowledged regulator dependence and the absence of convergence/truncation uncertainties. With a softened conclusion and additional uncertainty quantification, this could become a publishable paper. I do not see grounds for rejection, but the current version requires major revision."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Read this if you work on chiral EFT Hamiltonians. The paper tests the new quark-mass-dependent 3N force F2 [26] in medium-mass nuclei with IMSRG(2), using EMN 450 at N2LO/N3LO, and finds that adding F2 does not improve agreement with experiment across oxygen, calcium, and tin. The interesting part is not the null result itself but the decomposition: a Hartree-Fock analysis shows F2's main effect is to shift the short-range LECs cD/cE during refits, while the direct F2 contribution in medium-mass nuclei is small. That is a useful, clean message for Hamiltonian builders.\n\nThe paper is honest. It uses established machinery (NuHamil, imsrg++), fits two strategies (GT endpoint vs 16O), and reports the expected correlations. The authors explicitly note in the introduction that spectral-function regularization changes the counterterm structure, and that their calculation is conditional on dimensional regularization. They also note the cD value in the 16O fits is loosely constrained. Good.\n\nNow the soft spots. First, the headline conclusion—\"no direct evidence to justify promoting F2\"—is weaker than the paper's framing suggests. If the physical regulator requires additional short-range counterterms, the fitted cD/cE values and the reparametrization picture could change. The authors flag this in Sec. I, but the Sec. V conclusion is stated without the caveat, and the cited [29] is an independent preprint. The conclusion should be rephrased as conditional on DR.\n\nSecond, the claim that \"the contributions of the F2 interaction itself always remain small\" is not uniformly supported. In Fig. 4, the direct F2 expectation value in 3H looks non-negligible (the text even says it can be \"significant\" for light systems). What is small is the contribution in heavier nuclei like 16O. The sentence should be qualified.\n\nThird, there are no convergence checks or chiral-truncation uncertainty estimates. The paper argues F2 does not improve agreement because the changes are uniform and within a few percent, but without quantifying IMSRG truncation errors it's hard to know how much of that is meaningful. A missing uncertainty estimate for a null result is more than cosmetic.\n\nFourth, the 16O fit strategy makes the 16O agreement partly by construction; the authors acknowledge this implicitly through the loose cD constraint. The medium-mass trends are still informative, but this should be stated more directly.\n\nOverall, the core calculation is sound and the negative result is a useful data point. It belongs in the literature and deserves a serious referee, but it needs a revised conclusion that carries the regulator caveat and qualified \"small F2\" claim. If I were the editor I'd send it to review.","headline":"A careful, honest numerical study showing F2 mostly shifts short-range 3N LECs in medium-mass nuclei, but the headline no-promotion conclusion is regulator-dependent and the no-improvement claim lacks uncertainty quantification.","tokens_in":10681,"tokens_out":3219,"would_cite":true,"duration_ms":32330,"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 the new quark-mass-dependent F2 three-nucleon interaction changes medium-mass nuclei mainly by shifting fitted short-range couplings, and finds no evidence to promote it to lower order in the standard chiral power coun","keywords":["three-nucleon forces","chiral effective field theory","quark mass dependence","ab initio nuclear structure","medium-mass nuclei","charge radii","power counting","IMSRG"],"falsifier":"Repeat the calculation with spectral-function regularization and the required promoted counterterms, refit cD/cE/F2 to the same observables, and test the resulting Hamiltonian on the oxygen and calcium chains; if the direct F2 expectation value in 16O becomes sizable or the refitted interaction systematically improves the 48Ca–52Ca charge-radius difference to the experimental 0.530 fm^2, the paper's central conclusion is wrong.","tokens_in":9816,"feed_emoji":"⚛️","tokens_out":5695,"duration_ms":54213,"temperature":0.7,"pith_summary":"The paper asks whether a newly identified quark-mass-dependent three-nucleon force, the F2 term, should be treated as a leading correction to nuclear forces. It combines this term with standard chiral interactions and fits the low-energy couplings two ways: to few-body observables alone, or additionally to the ground-state energy and radius of 16O. The central finding is that F2's direct contribution stays small; its apparent impact on medium-mass nuclei comes almost entirely from shifting the fitted short-range couplings cD and cE. Across oxygen and calcium isotopes, including F2 does not systematically improve agreement with experiment and does not explain the large charge-radius jump from 48Ca to 52Ca. The authors conclude there is no evidence to promote F2 to lower order in the standard chiral power counting.","feed_headline":"No evidence to upgrade quark-mass three-nucleon force","feed_subtitle":"Its apparent effects in medium-mass nuclei come from refitted short-range couplings, not from the new interaction itself.","key_machinery":"The load-bearing tool is an expectation-value decomposition: for 16O, Hartree-Fock energies are linear in each low-energy constant, so the contributions of c1, c3, c4, cD, cE, and F2 can be cleanly separated without interference. This decomposition shows the F2 term's direct contribution stays small, while F2 strongly correlates with cE in fits to the 3H binding energy, effectively sliding the short-range couplings. The paper also notes that the F2 interaction was implemented with dimensional regularization; with spectral-function regularization it would have a linear cutoff divergence, which would require promoting additional short-range counterterms.","core_discovery":"The central claim is that F2 acts as a reparametrization of the existing short-range three-nucleon interaction rather than a new physical effect. By decomposing the energy into individual 3N contributions using 3H Faddeev wave functions and Hartree-Fock 16O wave functions, the authors show that the expectation value of F2 itself is small in both systems, while adding F2 changes the fitted values of cD and cE—especially cE—which then alters the observables of heavier nuclei. This holds at N2LO and N3LO, and for bare and SRG-evolved interactions. Consequently, the paper does not find direct evidence that would justify promoting F2 to lower order in the chiral expansion in the standard power co","pith_inferences":["A corollary left implicit: claims about the strength of F2 derived from nuclear matter under an alternative power counting and dimensional regularization may not indicate its role in finite nuclei under standard power counting with a finite cutoff.","The correlation between F2 and cE suggests that few-body fits alone cannot disentangle quark-mass-dependent physics from short-range three-nucleon physics; observable combinations beyond energies and radii may be needed.","A testable extension: implement F2 with spectral-function regularization and the promoted counterterms, then check whether the direct F2 contribution stays small in 16O or whether the fitted couplings and finite-nucleus predictions shift.","Because the direct F2 contribution is small, the reparametrization view predicts that F2 will have negligible impact on observables insensitive to the fitted cD/cE combination—such as certain isotope shifts or ratio observables—which could be checked in future experiments."],"forward_implications":["F2 should not be promoted to a lower order in the standard chiral EFT power counting; no finite-nucleus observable studied here requires it.","The large F2 contributions seen in nuclear matter do not imply improved finite-nucleus predictions; they are largely absorbed into refit cD and cE values.","Fit strategies that constrain cD using 16O observables can mask F2 effects, making the new interaction hard to detect in bulk properties alone.","The unexplained charge-radius increase from 48Ca to 52Ca persists even when F2 is added as an additional fit parameter.","Tests of new three-nucleon forces in finite nuclei must separate direct interaction effects from reparametrization of existing low-energy constants."],"fun_headline_variants":["New 3N force just refits short-range couplings","No gain from quark-mass 3N force in heavier nuclei","Quark-mass 3N force fails to improve medium-mass nuclei","F2 interaction: no upgrade just refitted couplings"],"cache_read_input_tokens":2304,"weakest_assumption_plain":"The conclusion rests on using dimensional regularization for F2; with a spectral-function regulator the F2 term would have a linear cutoff divergence, so new short-range three-nucleon counterterms would need to be promoted, and the fitted couplings—and hence the conclusion—could change.","fun_headline_variants_meta":{"raw":{"variants":["New 3N force just refits short-range couplings","No gain from quark-mass 3N force in heavier nuclei","Quark-mass 3N force fails to improve medium-mass nuclei","F2 interaction: no upgrade just refitted couplings"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000965,"raw_usage":{"total_tokens":3940,"prompt_tokens":736,"completion_tokens":3204,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":480,"completion_tokens_details":{"reasoning_tokens":3135}},"tokens_in":480,"tokens_out":3204,"duration_ms":21274,"temperature":1.0,"reasoning_tokens":3135,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-03T14:21:38.670807+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Repeat the calculation with spectral-function regularization and the required promoted counterterms, refit cD/cE/F2 to the same observables, and test the resulting Hamiltonian on the oxygen and calcium chains; if the direct F2 expectation value in 16O becomes sizable or the refitted interaction systematically improves the 48Ca–52Ca charge-radius difference to the experimental 0.530 fm^2, the paper's central conclusion is wrong.","supporting_citations":[],"review_version":1}