{"id":"8429c790-f71a-438c-8296-dd2c0c3d5cd9","arxiv_id":"2411.19843","paper_version":2,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"A general Wilson-coefficient fit to B->D(*)tau nu data with scale-and-power parametrization gives M_NP <~ 27 TeV and shows negative P_tau(D) occurs only for CVL+CSR or CVL+CSL+CT operators.","lead":"This paper fits possible new physics effects to B meson decays into D or D* plus a tau and a neutrino, using a very general parametrization of new interactions. It finds the new physics scale can reach up to about 27 TeV for ordinary new particles, and that a negative tau polarization would single out specific interaction structures.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The 2σ SM-exclusion claim is not reproducible because the paper never states the Δχ² threshold used for the confidence regions; if the figures use Δχ²=4, the quoted exclusion is substantially overstated.","rationale":"The reader's weakest assumption is the neglect of O_VR and the arbitrariness of the |A_j|≤100 scan range. Those are legitimate caveats, but neither is the most load-bearing element of the paper's central claim. Adding O_VR would enlarge the NP parameter space and can only decrease χ²_min, making the SM point no more likely to be included; scanning |A_j| larger shifts the 27 TeV bound but does not by itself decide whether the SM is excluded. The claim that makes the paper noteworthy is precisely a 2σ exclusion of the SM, and that claim is a pure statistical statement about the confidence regions. In the text and figure captions, no Δχ² threshold is specified. This is a common and consequential omission: using Δχ²=4 instead of 6.18 or 12.59 can turn a modest tension into an apparent 2σ exclusion. Since the same undefined contours underlie Figs. 1–8, the 27 TeV bound, the negative-Pτ(D) statements, and the model-compatibility remarks in Sec. III are all downstream of this issue. The paper is otherwise transparent: it gives the fit function, data table, correlations for R(D)–R(D*) where available, and explicitly acknowledges that larger |A_j| raises the scale bound. A simple statement of the threshold, or a p-value for the SM point, would resolve the concern. Because the verdict was already CONDITIONAL, the recommendation is UNCHANGED, but the acceptance condition should include this clarification.","tokens_in":10836,"tokens_out":11944,"duration_ms":119947,"concrete_test":"Re-run the scan and redraw Figs. 1–8 using explicit thresholds: Δχ²=6.18 for 2D projections and Δχ²=12.59 for the joint 6D parameter region (or report the p-value of the SM point from a profile likelihood). Also state the exact Δχ² value used in the submitted figures. If the SM point is excluded under these thresholds, the qualitative conclusion survives; if it is not, the abstract's '2σ' and 'finite NP must exist' statements must be weakened to a sub-2σ tension.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim that 'the SM where Cj=0 is not included in our allowed region at the 2σ' (Sec. III, Fig. 5) is a statement about confidence-level contours, but the paper nowhere defines the Δχ² cut used to draw any of the '2σ' regions in Figs. 1–8. Eq. (35) defines only the χ² function. The fitted parameter set is six-dimensional (α, M_NP, A_VL, A_SL, A_SR, A_T), and the plots are, at most, 2D projections of that space. The correct thresholds are Δχ²=6.18 for a 2D 95.45% region and Δχ²=12.59 for the 6D joint 95.45% region; a single-parameter 2σ cut of Δχ²=4 corresponds to a 1.5σ ellipse in 2D and to less than a 1σ volume in the 6D fit. If the figures were generated with Δχ²=4, the SM point may lie inside the true 95% region, so the conclusion 'finite NP effects must exist' would not follow at 2σ. This concern is independent of the O_VR neglect and the |A_j|≤100 scan range: it attacks the statistical meaning of the headline exclusion itself.","agreement_with_reader":"disagree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper performs a global χ² fit to the B→D(*)τν observables R(D), R(D*), Pτ(D*), and FL(D*) using a model-independent parametrization of new-physics Wilson coefficients, C_j = A_j (v/M_NP)^α times RG factors, with α, M_NP, and four couplings A_VL, A_SL, A_SR, A_T scanned over chosen ranges. The fit includes experimental correlations and imposes Br(B_c→τν)<0.3. The main claims are: (i) within the scan, the new-physics scale is bounded by M_NP ≲ 27 TeV for α=2; (ii) the SM point (all C_j=0) is not in the allowed region at 2σ, so finite NP must exist; (iii) negative Pτ(D) is possible only for certain operator combinations; and (iv) the sum rule for R(Λc) works well. The paper also presents predictions for R(J/Ψ) and R(Λc).","tokens_in":11109,"tokens_out":5856,"duration_ms":49670,"significance":"If the stated significance of the SM exclusion and the M_NP bound were robust, the paper would provide useful guidance for NP model building in b→cτν transitions. The analysis uses up-to-date formulae from Ref. [4], includes the available experimental correlations, and offers a convenient parametrization of the Wilson coefficients. The check of the R(Λc) sum rule is a nice consistency test. The main experimental finding—R(D*) lying above the SM—is visible in the fits, and the observation that negative Pτ(D) selects specific Lorentz structures is a potentially interesting phenomenological target. However, the central statistical claims are not presently reproducible because the χ² threshold for the reported confidence regions is not defined, and the impact of theory uncertainties and the neglected O_VR operator is not assessed. These issues must be fixed before the results can be taken at face value.","major_comments":[{"comment":"The paper never states the Δχ² threshold used to draw the '2σ' contours. Equation (35) defines only the χ² function. Because the fit has six free parameters (α, M_NP, A_VL, A_SL, A_SR, A_T) and the plots are at most two-dimensional projections, the 95.45% contour requires Δχ²=6.18 for a profiled two-dimensional region and Δχ²=12.59 for a joint six-dimensional region; if the contours were drawn with Δχ²=4 (the one-parameter 2σ cutoff), the claim that the SM point is excluded at 2σ and the α upper bound quoted in Sec. III (α ≲ 6.4, Fig. 2) would not hold at the stated confidence. The author should state the threshold explicitly and regenerate the contours with the correct threshold, or soften the exclusion claims accordingly.","section":"Section III, Figs. 1–8"},{"comment":"The numerical coefficients in the observable formulae (e.g., 1.01, 0.84, 1.49, 16.0, 5.17) are treated as exact, and the SM theory uncertainties quoted in Eqs. (4)–(8) are not propagated into the covariance matrix used in Eq. (35). Because the central claim is a finite-NP exclusion at the 2σ level, the effect of these theory uncertainties on the confidence regions must be quantified; otherwise the statistical significance is overestimated.","section":"Section II, Eqs. (20)–(26)"},{"comment":"The fit neglects the operator O_VR 'for simplicity,' but the abstract's phrase 'general and model-independent' and the operator-specific conclusions in Sec. III (e.g., that negative Pτ(D) arises only for (O_VL,O_SR) or (O_VL,O_SL,O_T)) are conditional on the chosen four-operator basis. If a right-handed vector current contributes, the fitted regions, the 2σ SM exclusion, and the M_NP bound all change. The paper should either extend the fit to include C_VR or explicitly state in the abstract and conclusions that the results apply only to the O_VL, O_SL, O_SR, O_T basis.","section":"Section II, after Eq. (19)"},{"comment":"The headline bound M_NP ≲ 27 TeV for α=2 depends on the arbitrary scan range |A_j| ≤ 100 and on the parametrization C_j = A_j (v/M_NP)^α. The text acknowledges the √k scaling for other coupling ranges, but the Abstract states the bound without this qualification. The bound is not a physical limit; it is a consequence of the chosen scan region. The Abstract and conclusions should report it as 'under the assumption |A_j| ≤ 100' or remove the unqualified number.","section":"Section III, Fig. 1 and Abstract"}],"minor_comments":[{"comment":"The caption lists panels with duplicated labels, '(a) CSL vs. C_VL, (b) C_SR vs. C_VL, (a) C_T vs. C_VL, (b) C_T vs. C_SL, and (e) C_SR vs. C_SL'; the panel labels (a)–(e) should be sequential and consistent.","section":"Fig. 5 caption"},{"comment":"The sentence 'Figure 3 (c) shows that most of Br(B_c → τν) values are safely less than ∼0.1' appears to reference the wrong panel; Fig. 3(d) shows Br(B_c → τν) as a function of α.","section":"Page 10, text after Fig. 3"},{"comment":"The sentence 'Among 4 Wilson coefficients C_VL,SL,SR,T in out analysis two or three of them can be zero' contains a typo ('out' for 'our') and is confusing; it should state that two or three of the coefficients can be nonzero (since not all of them vanish).","section":"Page 14, Sec. III"},{"comment":"The constraint Br(B_c → τν) < 0.3 is very weak compared with current bounds; the author should cite the latest experimental limit or justify the choice of the 'moderate' 30% bound.","section":"Section II, Eq. (34)"}],"recommendation":"major_revision","confidential_remarks":"The decisive issue is the undocumented Δχ² threshold for the confidence regions. I recommend requesting that the author state the threshold and, ideally, provide a table of Δχ² values for the best fit and the SM point, or share the fit code. The theory-uncertainty and O_VR-neglect issues are standard but should be addressed in a revision; they affect the reach of the claimed significance but are fixable within the manuscript's scope."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Quick take: this is a workmanlike, honest fit to R(D(*)) plus polarization data. The genuinely new result is the claim that negative Pτ(D) is reachable only with the operator combinations (C_VL, C_SR) or (C_VL, C_SL, C_T). The 27 TeV bound is tied to the arbitrary |A_j|≤100 scan range, but the author says so himself, twice, so that is not a hidden flaw. The real soft spot is statistical: the paper never states the Δχ² threshold used for any of its \"2σ\" contours, so the headline claim that the SM is excluded is not reproducible as reported.\n\nWhat the paper does well: it applies the (v/M_NP)^α parametrization, carried over from the author's R(K*) papers, to b→cτν with updated data; uses current formulas; includes experimental correlations in Table I; imposes the Bc→τν bound; and checks the R(Λc) sum rule. The negative-Pτ(D) operator-combination result is a genuinely useful discriminating observation that I did not find in the cited literature. The author is also transparent that the M_NP bound scales as √k with the coupling range, both in Sec. III and in the conclusions. Credit where it is due.\n\nSoft spots, in proportion. First and most important: the missing Δχ² definition. The fit is six-dimensional (α, M_NP, and four couplings), the plots are 2D projections, and \"2σ\" is never defined. If the contours were drawn with Δχ²=4, they correspond to a 1.5σ ellipse in 2D and less than a 1σ volume in the full fit; with a proper 6D 95% cut (Δχ²≈12.6) the SM point could sit inside. Since the SM-exclusion claim rests on the α upper bound, this has to be fixed before the statement means anything. The qualitative picture — R(D*) data are in tension with the SM — survives on the world average regardless. Second: O_VR is dropped \"for simplicity\" after Eq. (19); a right-handed operator would shift the fitted regions. Likely minor for the qualitative claims, but it deserves a quantitative comment. Third: the numerical coefficients in Eqs. (20)–(26) carry form-factor uncertainties that are not propagated into the χ², so the contours are optimistic.\n\nWho this is for: flavor theorists interpreting the R(D*) anomaly and model builders who want a quick compatibility check for leptoquark or charged-Higgs scenarios. It deserves a serious referee; I would send it to review with a request to state the contour thresholds, propagate theory errors, and comment on O_VR. The negative-Pτ(D) result is worth citing regardless.","headline":"A solid, honest R(D(*)) fit with one genuinely new observable result; the SM-exclusion claim needs its confidence thresholds stated before it can be taken at face value.","tokens_in":11673,"tokens_out":4655,"would_cite":true,"duration_ms":37260,"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":"The paper finds that the measured B→D(*)τν rates and polarizations exclude the Standard Model at the 2σ level, requiring finite new physics with a scale below about 27 TeV for ordinary tree-level mediators.","keywords":["B→D(*)τν decays","R(D) anomaly","tau polarization","Wilson coefficients","new-physics scale","b→c semileptonic transitions","leptoquarks","unparticles"],"falsifier":"Measure $P_\\tau(D)$ with high statistics: the Standard Model predicts $P_\\tau(D) = 0.331 \\pm 0.004$, while the paper finds that a significantly negative value requires new physics with either $\\{C_{VL}, C_{SR}\\}$ or $\\{C_{VL}, C_{SL}, C_T\\}$ active. A result of $P_\\tau(D) < 0$ at the $3\\sigma$ level would confirm the central claim and select the operator set; a result consistent with the SM prediction would undermine the case that finite new physics is needed.","tokens_in":10534,"feed_emoji":"⚛️","tokens_out":11155,"duration_ms":90202,"temperature":0.7,"pith_summary":"The paper asks whether the long-standing excess in $B \\to D^{(*)} \\tau \\nu$ decays can be explained by new physics and what that new physics would look like. It parameterizes every new-physics contribution by four Wilson coefficients with a common scale $M_{\\rm NP}$ and an adjustable power $\\alpha$, fits the world data on $R(D)$, $R(D^*)$, the $\\tau$ polarizations, and the $D^*$ longitudinal polarization, and imposes the $B_c \\to \\tau \\nu$ bound. The result is that the Standard Model point (all Wilson coefficients zero) lies outside the $2\\sigma$ allowed region, so a finite new-physics effect is required; for ordinary particles ($\\alpha = 2$) the scale is bounded by $M_{\\rm NP} \\lesssim 27$ TeV inside the scanned couplings. It also identifies the few operator combinations that can reverse the sign of the $\\tau$ polarization in $B \\to D$, a signature that would pin down the Lorentz structure of the new physics.","feed_headline":"B→D(*)τν data demand new physics below 27 TeV","feed_subtitle":"SM sits outside the 2σ fit; a negative τ polarization would expose the operator structure.","key_machinery":"The load-bearing object is the Wilson-coefficient parametrization $C_j(\\mu_b) = A_j (v/M_{\\rm NP})^\\alpha$ times renormalization-group factors, where $A_j$ collects the fermionic couplings, $M_{\\rm NP}$ is the new-physics scale, $v$ is the Higgs vacuum expectation value, and $\\alpha$ is a free exponent ($\\alpha=2$ for ordinary tree-level mediators, non-integer in the unparticle scenario). This single formula maps every new-physics model into a point in the five-dimensional parameter space, and the $\\chi^2$ fit then evaluates the analytic observable formulas. The argument is carried by the interference terms in the observable expressions: the signs of $\\mathrm{Re}[(1+C_{VL})(C_{SL}\\pm C_{SR})^*]$ and $\\mathrm{Re}[(1+C_{VL})C_T^*]$ decide whether $P_\\tau(D)$ can flip sign, and the large coefficients of $|C_T|^2$ keep the allowed tensor Wilson coefficient small.","core_discovery":"On its own terms, the paper establishes that the combined fit of $R(D)$, $R(D^*)$, $P_\\tau(D^*)$, and $F_L(D^*)$ — together with the $\\mathrm{Br}(B_c \\to \\tau \\nu) < 0.3$ constraint — excludes the Standard Model at the $2\\sigma$ level: the point $C_{VL}=C_{SL}=C_{SR}=C_T=0$ is not inside the allowed region ($\\chi^2_{\\rm min}/\\text{d.o.f.} \\approx 1.25$). Within the scanned parameter space ($-100 \\leq A_j \\leq 100$, $1\\text{ TeV} \\leq M_{\\rm NP} \\leq 100\\text{ TeV}$, $0 \\leq \\alpha \\leq 7$), the new-physics scale for ordinary tree-level mediators ($\\alpha=2$) satisfies $M_{\\rm NP} \\lesssim 27$ TeV, and the tension is concentrated in $R(D^*)$, which never overlaps the SM prediction in the fit. The polarization asymmetry $P_\\tau(D)$ can go negative only when the active operators are $\\{C_{VL}, C_{SR}\\}$ or $\\{C_{VL}, C_{SL}, C_T\\}$, and a large negative value would force $C_T \\neq 0$.","pith_inferences":["The bound $M_{\\rm NP} \\lesssim 27$ TeV is conditional on the four-operator basis; if the neglected right-handed vector interaction dominates the true new physics, both the fitted regions and the scale bound would shift.","The $\\sqrt{k}$ scaling of the mass bound gives a concrete search strategy: a few-TeV mediator with suppressed couplings is easier to test than a 27 TeV one, so future colliders should target small $|A_j|$.","The correlation lines $C_{SL} = +8.4 C_T$ and $C_{SL} = -8.9 C_T$ show that the fit prefers the latter, which acts as a model filter for leptoquark scenarios."],"forward_implications":["New physics must contribute at tree level to $b \\to c \\tau \\nu$: the SM point with all $C_j = 0$ is outside the $2\\sigma$ allowed region, so the data cannot be reproduced by the Standard Model alone.","For ordinary new particles ($\\alpha=2$) with $|A_j| \\leq 100$, the mediator mass is bounded by $M_{\\rm NP} \\lesssim 27$ TeV; weaker couplings lower the bound roughly as $\\sqrt{k}$.","If $P_\\tau(D)$ is measured negative, the active new-physics operators must be either $\\{C_{VL}, C_{SR}\\}$ or $\\{C_{VL}, C_{SL}, C_T\\}$, with a large negative value requiring $C_T \\neq 0$.","$R(\\Lambda_c)$ is predicted to stay above its SM value with no overlap in the allowed region, and the $R(\\Lambda_c)$--$R(D^{(*)})$ sum rule holds throughout the parameter space."],"supporting_citations":[{"why":"Provides the explicit leptoquark coupling combinations $A_{SL}$, $A_{VL}$ and the $\\mathrm{Br}(B_c \\to \\tau \\nu)$ formula used for constraints.","marker":"[3]"},{"why":"Supplies the updated numerical coefficients for the observable ratios in Eqs. (20)-(26), including $R(J/\\Psi)$ and $R(\\Lambda_c)$.","marker":"[4]"},{"why":"Provides the 2024 measured values of $R(D)$ and $R(D^*)$ that are the most recent experimental inputs in the fit.","marker":"[5]"},{"why":"Introduces the parametrization of new-physics Wilson coefficients by scale and couplings that Eq. (27) generalizes.","marker":"[10]"},{"why":"Supplies the explicit renormalization-group running factors for the scalar and tensor Wilson coefficients in Eqs. (29)-(30).","marker":"[14]"},{"why":"The earlier unparticle analysis that motivates letting $\\alpha$ be a free parameter and gives the $\\alpha \\geq 2$ or $4$ expectations.","marker":"[22]"},{"why":"The source of the $\\mathrm{Br}(B_c \\to \\tau \\nu) < 0.3$ bound imposed in the fit.","marker":"[32]"},{"why":"One source of the leptoquark-inspired correlation lines used as benchmarks in Fig. 5(d).","marker":"[45]"},{"why":"The other source of the leptoquark-inspired correlation lines used as benchmarks in Fig. 5(d).","marker":"[46]"}],"fun_headline_variants":["SM excluded at 2σ in B→D(*)τν fit, new physics ≤27 TeV","Negative τ polarization in B→D would expose new-physics operator","B→D(*)τν data rule out SM, hint at 27 TeV new physics","2σ excess in B→D(*)τν: new physics scale below 27 TeV","τ polarization in B→D decays can be negative only with new operators"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The analysis assumes that all new physics in these decays enters through just four interaction types whose strengths scale as $A_j(v/M_{\\rm NP})^\\alpha$, and it leaves out the right-handed vector type entirely.","fun_headline_variants_meta":{"raw":{"variants":["SM excluded at 2σ in B→D(*)τν fit, new physics ≤27 TeV","Negative τ polarization in B→D would expose new-physics operator","B→D(*)τν data rule out SM, hint at 27 TeV new physics","2σ excess in B→D(*)τν: new physics scale below 27 TeV","τ polarization in B→D decays can be negative only with new operators"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000461,"raw_usage":{"total_tokens":2326,"prompt_tokens":986,"completion_tokens":1340,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":602,"completion_tokens_details":{"reasoning_tokens":1228}},"tokens_in":602,"tokens_out":1340,"duration_ms":10424,"temperature":1.0,"reasoning_tokens":1228,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-12T05:46:23.346312+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure $P_\\tau(D)$ with high statistics: the Standard Model predicts $P_\\tau(D) = 0.331 \\pm 0.004$, while the paper finds that a significantly negative value requires new physics with either $\\{C_{VL}, C_{SR}\\}$ or $\\{C_{VL}, C_{SL}, C_T\\}$ active. A result of $P_\\tau(D) < 0$ at the $3\\sigma$ level would confirm the central claim and select the operator set; a result consistent with the SM prediction would undermine the case that finite new physics is needed.","supporting_citations":[{"cited_title":"NP effects, if exist, seems to enhance R(J/Ψ) while shrink R(Λc)","cited_arxiv_id":null,"evidence_quote":"Supplies the updated numerical coefficients for the observable ratios in Eqs. (20)-(26), including $R(J/\\Psi)$ and $R(\\Lambda_c)$."},{"cited_title":"Iguro, T","cited_arxiv_id":null,"evidence_quote":"Provides the 2024 measured values of $R(D)$ and $R(D^*)$ that are the most recent experimental inputs in the fit."},{"cited_title":"Fajfer and N","cited_arxiv_id":null,"evidence_quote":"Supplies the explicit renormalization-group running factors for the scalar and tensor Wilson coefficients in Eqs. (29)-(30)."},{"cited_title":"Celis, M","cited_arxiv_id":null,"evidence_quote":"The earlier unparticle analysis that motivates letting $\\alpha$ be a free parameter and gives the $\\alpha \\geq 2$ or $4$ expectations."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"The source of the $\\mathrm{Br}(B_c \\to \\tau \\nu) < 0.3$ bound imposed in the fit."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"One source of the leptoquark-inspired correlation lines used as benchmarks in Fig. 5(d)."}],"review_version":1}