{"id":"45d14a29-63f7-4e60-80ca-46c8ae415d63","arxiv_id":"2507.22123","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":15,"one_line_summary":"A global fit to inclusive semileptonic B decay moments and rate constrains all seven dimension-six new-physics parameters, finding no significant BSM signal but new bounds, especially on the right-handed vector Wilson coefficient.","lead":"Inclusive semileptonic B meson decays were analyzed for new-physics signatures by fitting all available kinematic-moment measurements against the full set of dimension-six effective operators, with seven new-physics parameters allowed to float. The fit finds no significant deviation from the Standard Model but produces new bounds, especially on a right-handed vector current, competitive with exclusive decay constraints.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The flagship CVR bound depends on the q2-moment fit, and the paper's own Section 3.2 admits the Belle/Belle II q2 tension will affect BSM results; without a stability test dropping or reweighting one experiment, the 'dominant bound' claim is not secured.","rationale":"I agree with the reader's identification of the weakest assumption. The paper is transparent and analytically well cross-checked (Table 1), and the discrepancy with kolya and Ref. [21] is plausibly explained by a confirmed bug in the other package's re-expansion of normalized observables, so I do not see that as the primary fragility. The unresolved Belle/Belle II tension, however, is explicitly stated by the authors to affect BSM results, and it directly feeds the new constraint that makes the paper's headline claim. The theory-covariance prescription is uncalibrated, so the absolute size of every quoted bound is nominal; the chi2/d.o.f. near 0.58 suggests the uncertainties may be conservative, but the tension is not a conservative feature of the data and could instead indicate experimental systematics. A simple experiment-exclusion test would settle whether the CVR bound is robust or an artifact of the tension. Pending that test, a conditional verdict is appropriate.","tokens_in":25454,"tokens_out":5313,"duration_ms":58677,"concrete_test":"Refit scenario VI (only Re[CVR] != 0) and the full NP case under three variants: (i) exclude Belle q2 moments; (ii) exclude Belle II q2 moments; (iii) inflate the theory covariance for q2 moments by a factor of two. Compare the resulting 95% CL interval on Re[CVR] and the Delta-chi2 profiles with the nominal fit. If the interval changes by more than about 50% or the 'dominant bound' relative to exclusive constraints is lost, the central claim is not robust to the unresolved tension.","verdict_should_be":"CONDITIONAL","load_bearing_attack":"The central claim—that inclusive q2 moments provide the dominant bound on Re[CVR] and are competitive with exclusive constraints—rests on the combined Belle and Belle II q2-moment data. Section 3.2 discloses a small mutual tension between these two measurements and states: 'A resolution of this tension will therefore affect the results for BSM physics.' The fit absorbs the tension inside the conservative theory covariance inherited from Refs. [6,45], with chi2/d.o.f. = 42.58/74 ≈ 0.58 indicating that these uncertainties may be overestimated. If the tension originates from experimental systematics rather than underestimated theory error, then the covariance prescription does not correctly represent the data and the quoted 95% CL bound on Re[CVR] (Fig. 2, left panel) could shift substantially, potentially removing the claimed dominance over exclusive constraints. The paper performs no stability check under dropping either Belle or Belle II q2 moments, nor under reweighting their relative importance. Because the q2 moments are the single new ingredient that breaks the CVR blind direction of Ref. [22], this is the most load-bearing assumption of the paper.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper studies BSM effects in inclusive semileptonic B decays within the Weak Effective Theory. It derives the BSM contributions to the triple differential rate, the kinematic moments (lepton-energy, hadronic-mass, and q2 moments), partial rates, and total width through O(Λ_QCD^3/m_b^3), plus O(α_s) corrections for the right-handed vector current, and it releases the expressions as an ancillary Mathematica file. It then performs least-squares fits of the full set of inclusive measurements, simultaneously extracting HQE parameters and NP Wilson coefficients, for five single-mediator scenarios and for the full seven-parameter WET. The main results are that no significant BSM signal is found (the full NP fit improves χ^2 by 6.54 for 7 degrees of freedom), that in several scenarios the inclusive data provide new bounds that are competitive with exclusive fits, and that the q2 moments break the blind direction in the Re[CVR]–|Vcb| plane identified in Ref. [22]. The paper also identifies a flat direction between aT and |Vcb| that lowers the extracted |Vcb| in the full WET fit.","tokens_in":25652,"tokens_out":9484,"duration_ms":104336,"significance":"If correct, this is a valuable first global analysis of inclusive semileptonic B decays in the full WET basis, with HQE parameters fitted simultaneously with NP coefficients. The paper's strengths include explicit cross-checks against earlier calculations (Table 1), numerical tables of the NP coefficients for all observables, an ancillary expression file, and a clear statement of the assumptions (small Wilson coefficients, expansion to O(a_i^2)). The no-BSM conclusion is robust: the Δχ^2 improvement in the full NP fit is only 6.54 for seven additional degrees of freedom, and all single-mediator scenarios are consistent with the SM. The headline claim that q2 moments provide competitive CVR constraints is important and testable. The main weakness is that the flagship bound is not tested for stability under the known Belle/Belle II q2-moment tension and under the conservative theory-covariance prescription, as detailed in the major comments.","major_comments":[{"comment":"The claim that the q2 moments provide the dominant bound on Re[CVR] rests entirely on the combined Belle and Belle II q2-moment data. The paper itself states at the end of Section 3.2 that the SM fit clearly prefers Belle II while the global fit's preference is less pronounced, and that a resolution of this tension will affect the BSM results. Yet no fit is shown with the two experiments separated, with one dropped, or with reweighted data. Because the q2 moments are the single new ingredient that breaks the CVR blind direction of Ref. [22], please add such a stability test and report how the 95% CL bound in the left panel of Fig. 2 and the 'competitive with exclusive' statement change.","section":"Section 3.2, Fig. 2"},{"comment":"The quoted bounds are Δχ^2 statements built on the theory-covariance prescription of Refs. [6,45], which yields χ^2/d.o.f. = 42.58/74 ≈ 0.58 in the SM fit. The authors describe these uncertainties as conservative. If they are indeed overestimated, the 95% CL intervals in Fig. 2 would be wider than shown and the competitiveness with exclusive constraints could be reduced. I request a quantitative sensitivity test, such as rescaling the theory covariance or replacing it by an alternative estimate, to assess how much the flagship bounds on Re[CVR] and aT move.","section":"Section 3.2, Eqs. (3.11) and Fig. 2"},{"comment":"The sentence 'the q2 moments provide a strong constraint that does not suffer from this problem, and thereby the dominant bound on CVR' is stated without the qualification that it applies to a real right-handed coefficient. The very next paragraph shows that allowing Im[CVR] changes the fit drastically and that the best-fit point of scenario I is complex. Please state explicitly that the competitive bound refers to Re[CVR] with Im[CVR]=0, and provide the corresponding constraint for complex CVR (even if weaker) so that the abstract's claim of generic BSM sensitivity is not overstated.","section":"Section 3.2, paragraph on CVR"}],"minor_comments":[{"comment":"The caption reads '2D profile Δχ^2 plot in the Re[CVR]−|Vcb| (left) and aT−|Vcb| (right) planes', but the text describes three panels (scenario VI, VII, IV). Please update the caption to describe the central panel and to identify the right panel as scenario IV / aT−|Vcb|.","section":"Figure 2 caption"},{"comment":"The 68.3% interval for cos(δPT), 0.91 +0.09 −1.91, extends below the physical lower bound −1. Please clarify whether this is an artifact of the parabolic interpolation of a non-Gaussian profile and how the reader should interpret the interval.","section":"Table 4"},{"comment":"The Introduction states 'With the exception of Ref. [17], only the total decay rate has been used as a constraint on BSM physics', but Section 3.2 credits Ref. [22] with a fit to lepton-energy and hadronic-invariant-mass moments including NP. Please correct the Introduction to avoid the contradiction.","section":"Introduction vs. Section 3.2"},{"comment":"The text claims ζRR = ζSM 'holds to all orders in the perturbative and power expansions', but Table 11 lists ζSM with O(α_s^2), O(α_s^3) and O(α_em) terms while ζRR only contains the leading, power and O(α_s) terms. Please clarify that the identity is not fully implemented in the numerical coefficients and estimate the numerical impact on the a_R bound.","section":"Section 3.1, text after Eq. (3.10)"}],"recommendation":"major_revision","confidential_remarks":"This is a strong paper and the no-BSM conclusion is convincing. The major revision is driven by robustness checks I would like to see before the headline competitiveness claim is published. I do not see a need for new calculations beyond the stability and sensitivity tests described in the major comments. The paper is within JHEP's scope."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The genuinely new thing here is the fit, not the formulas. The moment-level NP calculations largely reproduce earlier work, as the authors honestly state in Table 1, but putting all seven independent WET parameters into one global fit of the inclusive observables is new, and the result that q2 moments break the CVR blind direction of Ref. [22] is a real finding. The bounds on CVR, tensor, and scalar coefficients being competitive with exclusive fits is plausible and worth taking seriously.\n\nThe paper is unusually candid. It discloses the Belle/Belle II q2-moment tension and says explicitly that resolving it will affect the BSM results. It also admits the flat direction that pulls |Vcb| down to 35.1e-3 in the full NP fit, and it flags that its theory uncertainties are conservative (chi2/dof around 0.58). That kind of transparency makes the analysis easier to trust.\n\nThe soft spots are real but localized. The flagship CVR bound depends on the q2 moments, and the paper does not test stability under dropping or reweighting either Belle or Belle II. Given the disclosed tension, that is a genuine gap, not a manufactured one. The stress-test note is right: the claim that q2 moments provide the dominant CVR bound is not fully secured. Second, the numerical NP moments only partially agree with the public kolya package, and the comparison is not shown in detail. The paper explains part of the discrepancy as a re-expansion issue in Ref. [21], but a table or appendix with a direct numerical comparison would be much more convincing. Third, the absolute size of every bound carries the inherited, uncalibrated theory covariance; this makes the bounds nominal rather than absolute, though the no-BSM conclusion itself does not depend on that calibration.\n\nThe central argument holds up: no significant BSM signal, robust to the conservative uncertainties. The paper is a competent piece of phenomenology with clear value for B-physics and WET practitioners. I would bring it to reading group and would cite it. It deserves a serious referee; the referee should ask for a q2-moment stability test and a fuller kolya comparison, but neither issue warrants rejection.\n\nRecommendation: send to peer review, with those two items as requested revisions.","headline":"Solid first global fit of inclusive semileptonic B decays with the full WET basis; the flagship CVR bound leans on q2-moment data that deserve a stability check, but the paper is worth refereeing.","tokens_in":26365,"tokens_out":1157,"would_cite":true,"duration_ms":16142,"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":"A global fit to inclusive semileptonic B-decay moments yields new, competitive bounds on beyond-Standard-Model Wilson coefficients, with the q² moments giving the dominant constraint on a right-handed vector current.","keywords":["inclusive semileptonic B decays","weak effective theory","Wilson coefficients","heavy quark expansion","q^2 moments","right-handed vector current","Vcb extraction","new physics constraints"],"falsifier":"Re-run the global fit once with Belle's $q^2$ moments and once with Belle II's; if the two resulting bounds on ${\\rm Re}[\\tilde{C}_{V_R}]$ differ by more than the quoted uncertainty, the claim that the $q^2$ moments dominate the constraint is not robust.","tokens_in":25067,"feed_emoji":"⚛️","tokens_out":8325,"duration_ms":90298,"temperature":0.7,"pith_summary":"Semileptonic B-meson decays to charm and light leptons have usually been treated as a way to pin down the CKM element $|\\tilde{V}_{cb}|$, with new physics handled as a nuisance. This paper argues that they are also a competitive direct probe of physics beyond the Standard Model. The authors compute how all dimension-six operators of the weak effective theory shift the measured kinematic moments and total rate through order $\\Lambda_{\\rm QCD}^3/m_b^3$, including the $\\mathcal{O}(\\alpha_s)$ corrections for a right-handed vector current, and fit the full inclusive dataset. The key finding is that the $q^2$ moments, measured by Belle and Belle II, remove a known blind direction and give the dominant bound on the right-handed vector Wilson coefficient $C_{V_R}$, making inclusive constraints complementary to and competitive with exclusive decays. In the full seven-parameter fit the Standard Model remains compatible with the data at the $0.7\\sigma$ level.","feed_headline":"Belle q2 moments sharpen inclusive bounds on right-handed currents","feed_subtitle":"A global fit to B decay moments makes inclusive data competitive with exclusive searches for new physics.","key_machinery":"The machinery is a local operator product expansion for the hadronic tensor, expressed through the heavy-quark expansion in which the inclusive decay is governed by structure functions $w_i(\\hat{q}^2,\\hat{q}_0)$ obtained from the forward scattering amplitude. The paper parametrizes new physics by seven real quantities $\\{a_R, a_S, a_P, a_T, \\cos\\delta_R, \\cos\\delta_{ST}, \\cos\\delta_{PT}\\}$ and works out the coefficients $\\xi_{XY}$ in the expansion of each moment observable. The $q^2$ moments $Q_n(q^2_{\\rm cut})$ play a special role: unlike lepton-energy and hadronic-mass moments, they do not suffer from the $|\\tilde{V}_{cb}|$--${\\rm Re}[\\tilde{C}_{V_R}]$ blind direction, and the quadratic tensor coefficient $\\zeta_{TT}$ in the total width is an order of magnitude larger than the other NP coefficients, which creates the flat direction in the full fit.","core_discovery":"On the paper's own terms, the central discovery is that the first global fit to all available inclusive $\\bar{B}\\to X_c\\ell\\bar{\\nu}$ observables in the full dimension-six WET basis does not reduce to a restatement of the total rate. The $q^2$ moments break the near-degeneracy between $\\tilde{V}_{cb}$ and ${\\rm Re}[\\tilde{C}_{V_R}]$ that had made the right-handed vector bound uncompetitive, and thereby supply the dominant constraint on $C_{V_R}$. In the single-mediator scenarios the fit yields bounds complementary to exclusive $B\\to D^{(*)} \\ell\\nu$ analyses, while all NP parameters remain consistent with the SM, with the best fit point compatible at the $0.7\\sigma$ level. With all Wilson coefficients complex and free, the data permit large cancellations among tensor, scalar and pseudoscalar contributions along a flat direction, which drags $|\\tilde{V}_{cb}|$ down to $(35.1^{+4.2}_{-3.6})\\times 10^{-3}$ with an uncertainty nearly ten times the SM fit; the paper interprets this as a degeneracy to be resolved by additional observables, not as evidence of new physics. It also flags that the small Belle--Belle II tension in $q^2$ moments affects the BSM conclusions.","pith_inferences":["If the small Belle--Belle II discrepancy in $q^2$ moments is experimental rather than theoretical, the quoted $C_{V_R}$ bound and the \"competitive with exclusive\" claim would shift; the paper does not test this by dropping one experiment.","The dominance of $q^2$ moments suggests that refined Belle II $q^2$-moment measurements, especially at lower $q^2$ cuts, would translate almost directly into tighter $C_{V_R}$ bounds.","Because the inclusive OPE and exclusive form-factor analyses use independent hadronic inputs, a combined inclusive-plus-exclusive fit should separate nonperturbative HQE parameters from new-physics Wilson coefficients more cleanly, and lattice determinations of the HQE parameters would further remove degeneracies.","The large $\\zeta_{TT}$ enhancement near $q^2=0$ implies that measurements of the low-$q^2$ region, where the tensor contribution is amplified, could be the most sensitive place to look for tensor operators."],"forward_implications":["The $q^2$ moments provide the dominant inclusive bound on ${\\rm Re}[\\tilde{C}_{V_R}]$, a constraint that does not suffer from the blind direction of the older lepton-energy and hadronic-moment fits.","In each of the five single-mediator scenarios, inclusive data alone give constraints complementary to and competitive with exclusive $B\\to D^{(*)} \\ell\\nu$ fits, with an implied new-physics scale $\\Lambda_{\\rm NP} \\gtrsim 1.1$ TeV.","No scenario improves the SM description significantly; the full WET best fit is compatible with the SM at the $0.7\\sigma$ level.","Allowing all seven Wilson-coefficient parameters to float opens a flat direction from tensor--scalar--pseudoscalar interference, lowering $|\\tilde{V}_{cb}|$ to $(35.1^{+4.2}_{-3.6})\\times 10^{-3}$ with a much larger uncertainty.","A future measurement of the forward-backward asymmetry $A_{FB}$ in inclusive decays could remove this flat direction and sharpen the fit."],"supporting_citations":[{"why":"supplies the SM theoretical predictions and the data treatment for the $q^2$ moments that anchor the fit.","marker":"[6]"},{"why":"provides the $\\mathcal{O}(\\Lambda_{\\rm QCD}^3/m_b^3)$ NP structure functions that the paper reproduces and extends.","marker":"[20]"},{"why":"is the prior NP moments calculation whose observable re-expansion the paper identifies as partly incorrect.","marker":"[21]"},{"why":"is the earlier inclusive fit that found the $|\\tilde{V}_{cb}|$--${\\rm Re}[\\tilde{C}_{V_R}]$ blind direction, which the $q^2$ moments resolve.","marker":"[22]"},{"why":"gives the exclusive $b\\to c\\ell\\nu$ constraints against which the inclusive bounds are compared.","marker":"[27]"},{"why":"establishes the inclusive semileptonic fit methodology and the theory covariance used here.","marker":"[45]"},{"why":"provides the Belle $q^2$-moment measurements that drive the dominant $C_{V_R}$ bound.","marker":"[52]"},{"why":"provides the Belle II $q^2$-moment measurements whose small tension with Belle is disclosed in the paper.","marker":"[53]"},{"why":"computes the NNLO QCD corrections to the $q^2$ spectrum that update the SM predictions and shift $|\\tilde{V}_{cb}|$.","marker":"[58]"}],"fun_headline_variants":["Inclusive B decay q2 moments break degeneracy, tighten C_VR","First global fit to B semileptonic moments yields WET bounds","Belle q2 moments make inclusive B decays competitive for NP","Inclusive semileptonic B moments flag flat direction and limits"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The paper's flagship bound on the right-handed vector current presumes that the slight mismatch between the Belle and Belle II $q^2$-moment measurements is absorbed by the theory uncertainty; if that mismatch is an experimental artifact, the bound would shift.","fun_headline_variants_meta":{"raw":{"variants":["Inclusive B decay q2 moments break degeneracy, tighten C_VR","First global fit to B semileptonic moments yields WET bounds","Belle q2 moments make inclusive B decays competitive for NP","Inclusive semileptonic B moments flag flat direction and limits"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000224,"raw_usage":{"total_tokens":1478,"prompt_tokens":980,"completion_tokens":498,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":596,"completion_tokens_details":{"reasoning_tokens":421}},"tokens_in":596,"tokens_out":498,"duration_ms":6811,"temperature":1.0,"reasoning_tokens":421,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-06T12:04:20.005650+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Re-run the global fit once with Belle's $q^2$ moments and once with Belle II's; if the two resulting bounds on ${\\rm Re}[\\tilde{C}_{V_R}]$ differ by more than the quoted uncertainty, the claim that the $q^2$ moments dominate the constraint is not robust.","supporting_citations":[{"cited_title":"Inclusive semileptonic $\\Lambda_b$ decays in the Standard Model and beyond","cited_arxiv_id":"2006.13759","evidence_quote":"provides the $\\mathcal{O}(\\Lambda_{\\rm QCD}^3/m_b^3)$ NP structure functions that the paper reproduces and extends."},{"cited_title":"New physics contributions to moments of inclusive $b \\to c$ semileptonic decays","cited_arxiv_id":"2208.04282","evidence_quote":"is the prior NP moments calculation whose observable re-expansion the paper identifies as partly incorrect."},{"cited_title":"Limit on a Right-Handed Admixture to the Weak $b \\to c$ Current from Semileptonic Decays","cited_arxiv_id":"1003.4022","evidence_quote":"is the earlier inclusive fit that found the $|\\tilde{V}_{cb}|$--${\\rm Re}[\\tilde{C}_{V_R}]$ blind direction, which the $q^2$ moments resolve."},{"cited_title":"Measurement of Lepton Mass Squared Moments in $B \\to X_c \\ell \\bar \\nu_{\\ell}$ Decays with the Belle II Experiment","cited_arxiv_id":"2205.06372","evidence_quote":"provides the Belle II $q^2$-moment measurements whose small tension with Belle is disclosed in the paper."}],"review_version":1}