{"id":"cd8bec22-daf4-4cf9-9eb8-460d9fcda873","arxiv_id":"2602.10270","paper_version":2,"verdict":"ACCEPT","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"Production fraction ratios of B+, B0, and B0_s mesons at 13 TeV are measured with open-charm and charmonium decays, providing absolute normalizations and confirming isospin symmetry.","lead":"CMS used a special 'B parking' dataset with unbiased triggers to measure how often B+, B0, and B0_s mesons are produced in high-energy proton collisions, using their decays into charm particles and charmonium. The results give the first absolute normalization for charmonium-based production ratios and confirm isospin symmetry in b-quark production within 5% precision.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Absolute f_s/f_d and f_s/f_u values inherit the QCD-factorization ratio B(B0→K+D−)/B(B0s→π+Ds−) from Ref. [31], which the paper itself flags as individually discrepant; the f_d/f_u isospin test is independent.","rationale":"The reader's weakest-assumption identification is exactly the load-bearing point of the open-charm extraction. I read the manuscript as an honest, well-documented measurement: the theory dependence is stated, the isospin test and the B branching-ratio ratios are independent of the questionable ratio, and the results are consistent with earlier CMS/LHCb measurements. The central f_s/f_d and f_s/f_u values should be interpreted as conditional on the Ref. [31] ratio, but that is a disclosure, not a defect. No internal inconsistency or red flag was found. The proposed Belle cross-check would settle whether the concern is more than a caveat; until then the reader's ACCEPT with moderate confidence remains appropriate.","tokens_in":49197,"tokens_out":13127,"duration_ms":144627,"concrete_test":"Use Belle (or Belle II) Υ(5S) data to measure B(Bs0→π+Ds−) without relying on fragmentation fractions, combine with the B-factory value of B(B0→K+D−), and recompute the average f_s/f_d from Eq. (1) with this experimental ratio in place of Ref. [31]. If the shifted value differs from 0.219 by more than the 4.2% global theory uncertainty, the headline PFR values are not robust to the assumed QCD-factorization ratio.","verdict_should_be":"UNCHANGED","load_bearing_attack":"Section 4.1 concedes that Ref. [31] shows a 'puzzling substantial discrepancy' in the individual branching-fraction predictions, and the extraction then relies on the same theory for the ratio. That ratio is embedded in the prefactor and 1/(NaNF) in Eqs. (1) and (3). It therefore scales both headline values ⟨f_s/f_d⟩=0.219±0.008±0.014 and ⟨f_s/f_u⟩=0.218±0.008±0.015 and the charmonium normalizations c_sd/c_su (Eqs. 10–11). A bias of the order of the assigned 4.2% theoretical uncertainty would move the central values by ~4% while leaving the quoted statistical error unchanged. The combined f_d/f_u=0.956±0.043 is not affected because the ratio cancels in f_s/f_u ÷ f_s/f_d, and the branching-ratio results in Eqs. (7)–(9) are also independent of this ratio. So the concern is real, but it is an external, disclosed input rather than an internal inconsistency.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper reports a CMS measurement of B-meson production fraction ratios in proton-proton collisions at sqrt(s)=13 TeV, using the 2018 B-parking data set (41.6 fb^-1) with high-rate single-muon triggers. The open-charm modes B+ -> pi+D0, B0 -> pi+D-, and B0s -> pi+Ds- are used to measure f_s/f_d and f_s/f_u as functions of B pT (8-60 GeV) and |y| (<2.25), yielding averages <f_s/f_d> = 0.219 +/- 0.008 +/- 0.014 and <f_s/f_u> = 0.218 +/- 0.008 +/- 0.015. The same data set provides charmonium measurements of relative PFRs R_s and R_s^d, and open-charm results are used to set an absolute normalization for charmonium-based PFRs via constants c_sd and c_su. Three charmonium-to-open-charm branching-fraction ratios are also measured, with improved precision for the B0s modes. A combined f_d/f_u = 0.956 +/- 0.043 is obtained and used to test isospin invariance, which is found to hold within about 5% precision.","tokens_in":49459,"tokens_out":15578,"duration_ms":151005,"significance":"If the results hold, the paper provides the first absolutely normalized charmonium-based PFR measurement at CMS, a useful input for Bs branching-fraction determinations (e.g., Bs -> mu+ mu-), and a precise test of isospin invariance in pp collisions. The analysis is technically careful: signal yields are extracted from binned maximum-likelihood fits with shape constraints from simulated samples; systematic uncertainties are explored with alternative parameterizations; probe- and tag-side categories provide cross-checks; and the agreement with previous CMS/LHCb measurements is documented. The data are available in HEPData. The main caveat is that the absolute values of f_s/f_d, f_s/f_u, and the normalizations c_sd/c_su inherit the QCD-factorization ratio B(B0 -> K+D-)/B(B0s -> pi+Ds-) from Ref. [31], which is disclosed and assigned a 4.2% systematic uncertainty; the f_d/f_u isospin test and the branching-fraction ratios in Eqs. (7)-(9) do not depend on this input.","major_comments":[{"comment":"The central absolute results - <f_s/f_d>, <f_s/f_u>, and the normalizations c_sd/c_su in Eqs. (10)-(11) - are multiplied by the QCD-factorization ratio B(B0 -> K+D-)/B(B0s -> pi+Ds-) from Ref. [31]. The text notes a 'puzzling substantial discrepancy' in the individual decay channels and states that the ratio is in good agreement with experiment, but no numerical comparison is given. Please (i) quote the theoretical and experimental values of this ratio and their uncertainties, (ii) justify that the individual discrepancies cancel in the ratio, and (iii) state explicitly in the abstract or conclusions that the absolute f_s/f_d and f_s/f_u values are conditional on this theory input. This is a disclosed external input, but it is load-bearing for the absolute scale.","section":"Section 4.1, Eq. (1)"}],"minor_comments":[{"comment":"The track selection column reads 'Track |eta|>2.4' in both tables; this should be '|eta|<2.4' as stated in the text of Section 5.1.","section":"Tables 3 and 4"},{"comment":"The row 'Total systematic uncertainty <7.9 <7.7 <7.2' appears inconsistent with the quadrature sum of the quoted global uncertainties (7.4%, 6.3%, 5.6%) and the maximum bin-to-bin uncorrelated uncertainties (up to 4.7%). For f_s/f_u, the quadrature sum would exceed 8%. Please clarify how the total is defined.","section":"Table 7"},{"comment":"The text states the simulation statistical uncertainty is 1.7-3.7%, while Table 7 lists 2.2-3.7% for all quantities. Please reconcile.","section":"Section 8.1"},{"comment":"Typo: 'rigtht' should be 'right'.","section":"Fig. 6 caption"},{"comment":"The phrase 'universal constants' may be too strong; the constants are validated only within the measured pT and rapidity range. Suggest rewording to 'constants within the measured kinematic range' or adding a caveat.","section":"Section 9.5"},{"comment":"The tag-side charmonium statistical uncertainty of +/-0.002 on f_d/f_u is surprisingly small compared to the other channels; a sentence explaining the event counts that drive this precision would help.","section":"Section 9.3"}],"recommendation":"minor_revision","confidential_remarks":"The paper is technically strong and I support publication after minor revision. The main point to address is the transparency around the theory ratio from Ref. [31]. The total systematic table inconsistency should also be fixed. No grounds for rejection."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Two things worth knowing. First, this is a genuinely useful heavy-flavor measurement from the CMS B-parking sample: it provides the first absolute normalization for charmonium-based production fraction ratios, and a clean f_d/f_u isospin test that does not assume isospin symmetry. Second, the absolute f_s/f_d and f_s/f_u values are only as good as the QCD-factorization ratio they inherit from Ref. [31]—the same reference the authors cite for a puzzling discrepancy in the individual branching-fraction predictions. That is a real caveat, but it is disclosed, external, and does not sink the paper.\n\nThe analysis itself is thorough. Binned maximum-likelihood fits with constrained shapes, alternative functional forms for systematics, a BDT with a sculpting check, sPlot subtraction for the nonresonant D_s component, probe-side versus tag-side cross-checks, and complete systematics tables. Results agree with LHCb and earlier CMS within uncertainties. The derived branching-fraction ratios improve the world-average precision for B_s -> J/psi phi relative to B_s -> pi D_s by about 40%, and the absolute normalizations c_sd and c_su are a practical tool for future charmonium analyses. HEPData record is provided.\n\nThe soft spot is exactly where the stress test points. Equations (1) and (3) embed the theory ratio B(B0 -> K+ D-) / B(B0s -> pi+ Ds-) from Ref. [31]. The paper openly says the individual predictions have a 'puzzling substantial discrepancy' with data. The ratio is better behaved, but it is still an external theory input. A bias at the level of the quoted 4.2% theoretical uncertainty would shift both headline f_s values by about 4%, with statistical errors unchanged. So those two numbers are best read as 'CMS + QCD factorization', not pure measurement. The branching-fraction ratios in Eqs. (7)–(9) are independent of that ratio, so those results retain their value. The f_d/f_u result is also independent and is the cleanest part of the paper: 0.956 ± 0.043, flat in pT and y, consistent with unity within 5%. That claim holds up.\n\nThe pT-averaged values are effective averages over 8 < pT < 60 GeV, not full-phase-space fractions; the paper says so, so that is a clarity point rather than an error.\n\nWho should care: heavy-flavor experimentalists, anyone normalizing B_s branching fractions, and PDG. The paper deserves a serious referee. I would send it to peer review; a referee should ask for an explicit statement of how much of the quoted systematic on f_s/f_d and f_s/f_u comes from the theory ratio, and possibly a cross-check against LHCb's f_s/f_d. But this is not a desk reject—it is a solid analysis with an honestly discussed external input.","headline":"Solid, careful CMS B-parking measurement: first absolute charmonium PFR normalization and a clean isospin test, but headline f_s values lean on a disclosed QCD-factorization ratio.","tokens_in":49935,"tokens_out":5002,"would_cite":true,"duration_ms":46643,"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":"Strange B meson fraction measured at 0.219; isospin holds to 5%","keywords":["B meson production fractions","production fraction ratios","f_s/f_d","f_s/f_u","isospin invariance","open-charm decays","charmonium decays","QCD factorization"],"falsifier":"Measure the two branching fractions entering the f_s/f_d extraction directly—for example at an electron-positron collider running on the Υ(5S) resonance, where B_s pairs are produced without fragmentation theory—and compare their ratio with the QCD-factorization prediction. A discrepancy beyond combined uncertainties would rescale the reported f_s fractions.","tokens_in":49073,"feed_emoji":"⚛️","tokens_out":7003,"duration_ms":72759,"temperature":0.7,"pith_summary":"This paper measures how often b quarks produced in high-energy proton collisions turn into the strange B_s meson instead of the non-strange B^+ and B^0 mesons. Using a specially recorded sample of about ten billion b hadrons, it reports average production fraction ratios <f_s/f_d> = 0.219 ± 0.016 and <f_s/f_u> = 0.218 ± 0.017, and a combined f_d/f_u = 0.956 ± 0.043, consistent with unity at the 5% precision level. This supports isospin invariance in B meson production at hadron colliders. The analysis also derives, for the first time, absolute normalization constants that convert charmonium-based relative measurements into absolute production fraction ratios. These numbers directly enter measurements of B_s branching fractions, including the rare B_s → μ+μ− decay.","feed_headline":"Strange B meson fraction measured at 0.219; isospin holds to 5%","feed_subtitle":"An unbiased sample of 10 billion b hadrons pins B_s production and sharpens rare-decay predictions.","key_machinery":"The central mechanism is a double-ratio construction. For the absolute f_s/f_d measurement, efficiency-corrected yields of the open-charm decays B0 → π+D− and B0_s → π+ D_s− (π−φ) are combined with the QCD-factorization prediction for the ratio B(B0 → K+D−)/B(B0_s → π+ D_s−) — a standard perturbative computation of nonleptonic B decay rates — with the pion/kaon ambiguity handled using the world-average ratio B(B0 → K+D−)/B(B0 → π+D−). For the charmonium channels, the relative yield ratios R_s and R_s^d are normalized to the open-charm results through double ratios c_sd and c_su, which cancel any pT dependence and can be applied to any charmonium sample.","core_discovery":"The paper claims that the production fractions of B_s relative to B^0 and B^+ are flat in the kinematic range 8 < pT < 60 GeV and |y| < 2.25, with average values <f_s/f_d> = 0.219 ± 0.008 (stat) ± 0.014 (syst) and <f_s/f_u> = 0.218 ± 0.008 (stat) ± 0.015 (syst). It further claims f_d/f_u = 0.956 ± 0.043, within 5% of unity and therefore consistent with isospin invariance in B meson production at hadron colliders. Using the open-charm results as a reference, the paper derives the first absolute normalizations for charmonium-based production fraction measurements, c_sd = 1.64 ± 0.14 and c_su = 2.02 ± 0.18, and reports branching fraction ratios between charmonium and open-charm decays that impr","pith_inferences":["Because the absolute normalizations are built as double ratios, they should remain valid for any charmonium-based analysis even if the open-charm yields are much smaller; reusing them would let future experiments skip the fully hadronic open-charm reconstruction.","The 5%-level isospin consistency still leaves a 2.2% uncertainty inherited from Υ(4S)-based branching fraction inputs; measuring f_d/f_u purely from proton-proton data without those inputs is a natural next step.","The paper's own note of a puzzling discrepancy between theory and experiment for the individual decay channels suggests that the f_s/f_d result could be tested by measuring the B_s → πD_s branching fraction directly at a B_s factory, which would also sharpen the global value of f_s/f_u."],"forward_implications":["The reported average values can be used as external inputs to normalize measurements of B_s branching fractions, including the rare decay B_s → μ+μ−, reducing its dominant systematic uncertainty.","The absolute normalization constants c_sd and c_su allow charmonium-based relative measurements to be reported as absolute production fraction ratios, not just shapes.","The charmonium-to-open-charm branching fraction ratios improve the precision of world averages, especially for B_s → J/ψφ.","Isospin invariance in B meson production at hadron colliders is confirmed at the 5% precision level."],"fun_headline_variants":["B_s fraction pinned at 0.219 from 10B b-hadron sample","Isospin holds: B production fractions flat in pT and y","First absolute charmonium B-fraction scales from LHC data","B_s fraction: 0.219 ± 0.014, isospin within 5% at LHC","Open-charm and charmonium decays fix B production ratios"],"cache_read_input_tokens":2304,"weakest_assumption_plain":"The absolute f_s/f_d and f_s/f_u values rest on the QCD-factorization prediction for the ratio B(B0 → K+D−)/B(B0_s → π+ D_s−); if that predicted ratio is biased, the measured production fractions shift by the same relative amount.","fun_headline_variants_meta":{"raw":{"variants":["B_s fraction pinned at 0.219 from 10B b-hadron sample","Isospin holds: B production fractions flat in pT and y","First absolute charmonium B-fraction scales from LHC data","B_s fraction: 0.219 ± 0.014, isospin within 5% at LHC","Open-charm and charmonium decays fix B production ratios"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000656,"raw_usage":{"total_tokens":2965,"prompt_tokens":992,"completion_tokens":1973,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":736,"completion_tokens_details":{"reasoning_tokens":1866}},"tokens_in":736,"tokens_out":1973,"duration_ms":12862,"temperature":1.0,"reasoning_tokens":1866,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-03T01:10:47.318828+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure the two branching fractions entering the f_s/f_d extraction directly—for example at an electron-positron collider running on the Υ(5S) resonance, where B_s pairs are produced without fragmentation theory—and compare their ratio with the QCD-factorization prediction. A discrepancy beyond combined uncertainties would rescale the reported f_s fractions.","supporting_citations":[],"review_version":1}