{"id":"3a215a9b-6c16-42a7-b851-1ae8dde227b0","arxiv_id":"1908.05729","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":2.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"A quark-diquark Faddeev model with QCD-kindred momentum dependence reproduces high-Q2 nucleon-to-resonance transition form factors and predicts Delta(1600) electroproduction form factors of definite sign over 0=2 and for the Delta demonstrates the essential role of momentum-dependent propagators and vertices. But the two frameworks are not varied along a single axis. Differences include: (i) the momentum dependence of the interaction; (ii) the current diagrams retained--the text states the CI 'suppresses two-loop diagrams'; (iii) diquark masses/content--QCD-kindred uses m0+=0.79 GeV, m1+=0.89 GeV, and in Fig. 6 these are changed to 0.85/0.85 to mimic meson-cloud; (iv) the dressed-quark anomalous magnetic moment, whose omission is shown in Fig. 5 (lower panels) to shift the REM zero. Because these ingredients change simultaneously, the agreement in Fig. 3 and Fig. 5 cannot be uniquely attributed to momentum dependence. The manuscript itself demonstrates the sensitivity to diquark content and DqAMM (Fig. 5 lower-right; Fig. 6 bottom panels), so the comparison is not a controlled probe of the running masses. The large MB-FSI mass shifts (0.2-0.3 GeV, Sec. II) and the inferred low-Q2 meson-cloud curves compound the issue: the claim that high-Q2 behaviour is unaffected by these omissions is assumed rather than demonstrated.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper presents a unified quark-diquark Faddeev-equation calculation of elastic and transition form factors for the nucleon, the Roper resonance N(1440), and the Delta(1232) and Delta(1600) resonances. It compares a 'QCD-kindred' framework, built with momentum-dependent propagators and vertices, against a symmetry-preserving contact-interaction (CI) framework in rainbow-ladder truncation. The central empirical claims are that the QCD-kindred results agree with CLAS data for the gamma* p -> N(1440) transition at x = Q^2/m_N^2 ≳ 2, that the CI framework fails there, and that the Delta(1232) magnetic transition form factor in the Ash convention is reasonably described by the QCD-kindred framework. The paper also makes predictions for the gamma* p -> Delta(1600) form factors at larger Q^2 and discusses the role of meson-cloud contributions at low x and of meson-baryon final-state interactions in the mass spectrum.","tokens_in":14834,"tokens_out":7324,"duration_ms":75519,"significance":"If the central claims hold, the paper supports the view that baryon electroproduction at large photon virtualities discriminates between momentum-dependent DSE kernels and contact interactions, and it provides testable predictions for CLAS12. The paper has clear strengths: the transition form factors are not fitted to the transition data, the inputs are taken from prior spectrum calculations, and the authors explicitly investigate sensitivity to the dressed-quark anomalous magnetic moment and to diquark content. They also label inferred meson-cloud contributions and normalized curves, which is honest. However, the significance is moderated by the fact that the main comparison does not isolate momentum dependence as the sole cause of the observed differences, and by the reliance on externally supplied meson-baryon mass shifts and inferred low-Q^2 contributions.","major_comments":[{"comment":"The statement that agreement with the CLAS data at x ≳ 2 'owes fundamentally to the QCD-derived momentum-dependence of the propagators and vertices' is a causal claim that the present comparison cannot establish. The QCD-kindred and contact-interaction calculations differ in at least four ways simultaneously: the momentum dependence of the kernel, the class of current diagrams retained (the text notes that the CI framework suppresses two-loop diagrams), the diquark masses and content (m0+ = 0.79 GeV, m1+ = 0.89 GeV in the main calculation, with m1+ changed to 0.85 GeV in Fig. 6), and the treatment of the dressed-quark anomalous magnetic moment, which Fig. 5 shows shifts the REM zero. Because these axes are not varied independently, the superiority of the QCD-kindred curves cannot be uniquely attributed to momentum dependence. I request either a controlled scan (for example, an interpolation between the two kernels with the current truncation and diquark content held fixed) or an explicit discussion of why the other differences cannot account for the observed discrepancy.","section":"Section III and Conclusions"},{"comment":"The identification of the computed Faddeev poles with the physical N(1440) and Delta(1600) relies on subtracting meson-baryon final-state-interaction mass shifts of 0.2–0.3 GeV that are taken from elsewhere, yet the manuscript does not show that the transition currents are insensitive to this subtraction or to the use of core versus physical masses in the kinematic factors of Eq. (2). Similarly, the low-x meson-cloud curves in Fig. 3 are inferred rather than derived, and the REM curve in Fig. 5 is rescaled by a factor of 1.34 to match the x = 0 datum, so those parts of the 'complete' curves are not predictions of the framework. The paper should state clearly which quantities are predictions and which are inputs, and should provide at least a crude estimate of the meson-baryon contamination at the x values used for the central comparison (x ≳ 2).","section":"Section II and Eq. (2)"},{"comment":"The Delta(1600) 'complete result' is presented alongside several variants (S-wave projections of the proton and Delta(1600), and an enhanced axial-vector diquark content obtained by setting m1+ = m0+ = 0.85 GeV), and the spread among these variants is large, especially for G_E^*. As written, the paper does not identify which curve is the actual prediction nor assign an uncertainty band, so the statement that CLAS12 data 'will allow us to test' the prediction is premature. A definite prediction, with the model spread quantified as a systematic uncertainty, should be specified before the comparison can be considered falsifiable.","section":"Section IV, Fig. 6"}],"minor_comments":[{"comment":"The listed masses (1.19, 1.73, 1.35, 1.79 GeV) are dressed-quark-core masses, not physical masses; a column heading or footnote making this explicit would prevent misreading.","section":"Section II, Table 1"},{"comment":"The role of the 1.34 factor should be stated explicitly: is it applied to REM itself or to G_E and G_M separately? As printed, it is unclear why a constant rescaling affects the reported zero locations.","section":"Fig. 5 lower-right panel"},{"comment":"The expressions 'x & 2' and similar should be typeset as x ≳ 2; the notation is ambiguous as rendered.","section":"Section III, text near Figs. 3 and 4"},{"comment":"The current decomposition in Eq. (5) uses several symbols (Λ+, R_λα, Σ_ΔN, λ±) that are only partially defined in the text; a one-sentence definition, or an explicit pointer to the appendix of Ref. [29], would improve readability.","section":"Eq. (5)"}],"recommendation":"major_revision","confidential_remarks":"This manuscript is largely a synthesis of results already published in Refs. [29, 37, 38, 75, 76]; the comparative discussion is useful, but the incremental content is modest. The editor may wish to consider whether the paper is best framed as a proceedings or review contribution, and whether the conclusions should be moderated along the lines of the major comments."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Quick take: this is a review-style paper that collects the authors' published Faddeev results into one narrative. It does not contain new computations, and it says so. What it does well: it gives a single coherent comparison of QCD-kindred and contact-interaction frameworks for the nucleon, Roper, Delta(1232), and Delta(1600) form factors, and it makes Delta(1600) predictions that CLAS12 can test. The figures appear consistent with the text: the QCD-kindred curves follow the CLAS data at higher Q2 for the Roper and for the Delta magnetic form factor, while the contact-interaction curves do not. The authors are transparent about the two big caveats: the Faddeev equation produces a dressed-quark core, not the full physical baryon, and meson-baryon final-state interactions plus meson-cloud effects are omitted or added by hand.\n\nThe soft spots are real but not fatal. First, the central claim that the agreement 'owes fundamentally to the QCD-derived momentum-dependence' is not established by the comparison. The two frameworks differ in more than the momentum dependence of propagators and vertices: the current truncation differs (the text says the contact-interaction suppresses two-loop diagrams), the diquark masses and content differ, and the dressed-quark anomalous magnetic moment is included in one framework and not the other. The paper itself shows that the DqAMM shifts the zero in REM and that changing diquark masses changes the Delta(1600) form factors, so the comparison is not a controlled single-axis probe. The claim should be softened to say the full QCD-kindred framework works better, not that momentum dependence is the demonstrated cause.\n\nSecond, there is some tuning. The 1.34 renormalization of REM and the m0+=m1+=0.85 GeV adjustment to mimic meson-cloud are clearly labeled, but they are not predictions. Third, no quantitative error bars are given for the theory curves, and the x in [6,12] extrapolations are based on analytic fits from x in [0,6]; the width of the band is a guess, not an uncertainty estimate. The citation pattern is fine — this is explicitly a summary of the authors' own prior peer-reviewed work, so self-citations are appropriate.\n\nWho is this for: hadron structure people who want a concise overview of the quark-diquark approach and its status against CLAS data. It is not a new research contribution. As a review, it deserves a serious referee if submitted to a venue that publishes such overviews; as a new research paper, an editor should probably desk-reject on novelty grounds. My recommendation: if it comes to you as a referee, take it, but ask the authors to reframe the momentum-dependence claim and clearly mark the tuned curves.","headline":"A clear, honest summary of the authors' quark-diquark program with testable Delta(1600) predictions, but the headline attribution to momentum dependence is not actually isolated by the comparison.","tokens_in":15439,"tokens_out":4080,"would_cite":false,"duration_ms":40719,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"A quark-diquark framework with QCD-kindred momentum dependence reproduces the measured Roper transition form factors at high momentum transfer, where a contact-interaction model fails.","keywords":["nucleon resonances","transition form factors","Roper resonance","Delta(1232)","Delta(1600)","quark-diquark Faddeev equation","Dyson-Schwinger equations","meson cloud"],"falsifier":"Measure the gamma* p to $\\Delta$(1600) transition form factors at momentum transfers between 2 and 5 $GeV^{2}$; if the electric or Coulomb quadrupole form factors show a zero crossing or sign change on that domain, the quark-core predictions are wrong. Alternatively, locating the zero of the $\\Delta$(1232) electric quadrupole ratio R_EM at a substantially different x than the framework predicts would show that orbital-angular-momentum or meson-cloud effects are not under control.","tokens_in":14330,"feed_emoji":"⚛️","tokens_out":10205,"duration_ms":94457,"temperature":0.7,"pith_summary":"This paper develops a unified description of the elastic nucleon form factors and the transition form factors for a photon exciting a proton into the N(1440) Roper resonance, the $\\Delta$(1232), and the $\\Delta$(1600), all from a single relativistic three-quark framework built on quark-diquark correlations. Its central claim is that the momentum dependence carried by QCD's dynamically generated quark and diquark masses is the decisive ingredient: the results obtained with QCD-kindred propagators and vertices reproduce the measured Roper transition form factors for x = $Q^{2}$/$m_N^{2}$ greater than about 2, while a symmetry-preserving contact-interaction model fails both quantitatively and qualitatively. The reason this matters is that it shows baryon electroproduction at large photon virtualities is a direct probe of how QCD's running masses and diquark correlations work inside hadrons. If the claim is right, the paper's predictions for the gamma* p to $\\Delta$(1600) form factors become concrete tests for the next generation of electron-scattering data.","feed_headline":"Roper data at high Q2 favor a running-mass quark-diquark model","feed_subtitle":"The same quark-diquark framework predicts Delta(1600) form factors that upcoming electron-scattering data can test.","key_machinery":"The load-bearing machinery is the Faddeev equation for a baryon as a relativistic bound state of a dressed quark and a non-pointlike diquark, with the diquark correlations continually breaking up and reforming. The key elements are the dressed-quark propagator, the diquark propagator, and the diquark Bethe-Salpeter amplitude; each baryon's wave function is expressed by eight scalar functions, and the electromagnetic current is a sum of six terms that probe the quarks and diquarks separately. The comparison that carries the argument is the contrast with a symmetry-preserving contact-interaction treatment: replacing QCD-kindred momentum dependence by a constant interaction in the same rainbow-ladder truncation makes the computed form factors too hard and removes some orbital-angular-momentum correlations. That contrast is what lets the authors attribute the high-x agreement to the momentum dependence of elementary quantities in QCD.","core_discovery":"On the paper's own terms, the discovery is that a Poincare-covariant Faddeev equation with fully dynamical, non-pointlike diquark correlations and interaction vertices whose momentum dependence follows QCD produces transition form factors that agree with experiment where a cruder scheme does not. Specifically, the gamma* p to N(1440) Dirac and Pauli form factors F*_1 and F*_2 are reported to agree with available data for x greater than about 2, with the low-momentum discrepancy attributed to meson-cloud contributions inferred separately; for the $\\Delta$(1232), the magnetic transition form factor in the Jones-Scadron convention is said to match the momentum dependence of the nucleon elastic form factors once the momentum transfer is high enough to pass the meson cloud; and for the $\\Delta$(1600), the paper offers predictions for magnetic dipole, electric quadrupole, and Coulomb quadrupole form factors that are consistent with the real-photon-point values and are presented as sensitive to the $\\Delta$(1600)'s wave function and deformation. The contact-interaction framework, by contrast, produces form factors that are too hard, curtails orbital angular momentum correlations, and suppresses two-loop current diagrams; comparing the two schemes identifies which observables are most sensitive to QCD's momentum-dependent elementary quantities.","pith_inferences":["The same comparison strategy could be extended to negative-parity excitations and heavier baryon multiplets; the paper's remark that other channels may contain additional diquark correlations suggests those sectors are where the framework would face its sharpest new tests.","If the Delta(1600) data do match the predictions, it would indicate that meson-baryon final-state interactions do not substantially reshape high-momentum transition currents, which would strengthen the case for extracting quark-core information directly from electroproduction data.","The analytic extrapolation used for x between 6 and 12 is an implicit prediction with stated confidence bands; when data reach that region, the width of those bands is itself a testable statement about how quickly the form factors approach their scaling behavior.","A natural extension is to apply the same machinery to the neutral-channel transitions, for which the paper shows projections and notes that no data exist; those would be independent tests of the isospin structure of the quark-diquark picture."],"forward_implications":["At x = Q^2/m_N^2 greater than about 2, the Roper transition form factors can be computed from the dressed-quark core alone, so future high-momentum-transfer data directly probe the running of QCD's quark masses.","The failure of the contact-interaction framework shows that measured form factors can discriminate between competing models of the quark-quark interaction; the data rule out a momentum-independent interaction.","The Delta(1232) magnetic transition form factor follows the same high-momentum dependence as the nucleon's elastic form factors, indicating that one dressed-quark core governs both.","The paper's Delta(1600) predictions, in which each form factor keeps a unique sign on the plotted domain, are testable with forthcoming electroproduction measurements and will be sensitive to the Delta(1600)'s wave function and deformation.","Higher partial waves in the baryon wave functions have a visible effect on all the transition form factors, with the electric quadrupole form factor most affected; hence that observable is a measure of orbital angular momentum correlations within baryons."],"supporting_citations":[{"why":"Supplies the Faddeev equation framework, the dressed-quark and diquark propagators, the diquark masses, and the six-term electromagnetic current used for all form factors.","marker":"[29]"},{"why":"Provides the large-Q^2 calculation and analytic extrapolation of the nucleon-to-Roper transition form factors that agree with data at x greater than about 2.","marker":"[37]"},{"why":"Provides the spectrum and Faddeev amplitudes for the N(1440) and Delta(1600) states used in the transition predictions.","marker":"[38]"},{"why":"Supplies the contact-interaction framework whose too-hard form factors are the comparison benchmark that highlights the role of momentum-dependent interactions.","marker":"[64]"},{"why":"Gives the meson-baryon final-state interaction mass shifts that justify treating the Faddeev results as the dressed-quark core.","marker":"[47]"},{"why":"Provides the measured Roper transition form factors to which the QCD-kindred results are compared on the high-x domain.","marker":"[11]"},{"why":"Provides the real-photon-point values of the Delta(1600) magnetic and electric transition form factors used to check the lowest-Q^2 predictions.","marker":"[12]"}],"fun_headline_variants":["Faddeev model matches nucleon-resonance data at high Q^2","Running-mass diquark framework predicts Delta(1600) form factors","QCD-kindred framework explains nucleon-transition form factors","Delta(1600) quadrupole predictions sensitive to wave function","Faddeev equation with running-mass diquarks matches data"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The calculation assumes that the missing meson-baryon interactions only change a resonance's mass and its low-momentum form factors, and do not reshape the high-momentum transition, which comes entirely from the three-quark core.","fun_headline_variants_meta":{"raw":{"variants":["Faddeev model matches nucleon-resonance data at high Q^2","Running-mass diquark framework predicts Delta(1600) form factors","QCD-kindred framework explains nucleon-transition form factors","Delta(1600) quadrupole predictions sensitive to wave function","Faddeev equation with running-mass diquarks matches data"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000574,"raw_usage":{"total_tokens":2735,"prompt_tokens":995,"completion_tokens":1740,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":611,"completion_tokens_details":{"reasoning_tokens":1645}},"tokens_in":611,"tokens_out":1740,"duration_ms":12509,"temperature":1.0,"reasoning_tokens":1645,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-14T13:28:19.377422+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure the gamma* p to $\\Delta$(1600) transition form factors at momentum transfers between 2 and 5 $GeV^{2}$; if the electric or Coulomb quadrupole form factors show a zero crossing or sign change on that domain, the quark-core predictions are wrong. Alternatively, locating the zero of the $\\Delta$(1232) electric quadrupole ratio R_EM at a substantially different x than the framework predicts would show that orbital-angular-momentum or meson-cloud effects are not under control.","supporting_citations":[{"cited_title":"Nucleon and ∆ elastic and transition form factors,","cited_arxiv_id":null,"evidence_quote":"Supplies the Faddeev equation framework, the dressed-quark and diquark propagators, the diquark masses, and the six-term electromagnetic current used for all form factors."},{"cited_title":"Nucleon-to-Roper electromagnetic transition form factors at large Q2,","cited_arxiv_id":null,"evidence_quote":"Provides the large-Q^2 calculation and analytic extrapolation of the nucleon-to-Roper transition form factors that agree with data at x greater than about 2."},{"cited_title":"Nucleon and Roper electromagnetic elastic and transition form factors,","cited_arxiv_id":null,"evidence_quote":"Supplies the contact-interaction framework whose too-hard form factors are the comparison benchmark that highlights the role of momentum-dependent interactions."},{"cited_title":"Disentangling the Dynamical Origin of P-11 Nucleon Resonances,","cited_arxiv_id":null,"evidence_quote":"Gives the meson-baryon final-state interaction mass shifts that justify treating the Faddeev results as the dressed-quark core."},{"cited_title":"Electroexcitation of nucleon resonances from CLAS data on single pion electroproduction,","cited_arxiv_id":null,"evidence_quote":"Provides the measured Roper transition form factors to which the QCD-kindred results are compared on the high-x domain."},{"cited_title":"Review of Particle Physics,","cited_arxiv_id":null,"evidence_quote":"Provides the real-photon-point values of the Delta(1600) magnetic and electric transition form factors used to check the lowest-Q^2 predictions."}],"review_version":1}