{"id":"06c6bd72-90d4-4bcf-8087-6d05d460914c","arxiv_id":"1908.11619","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":6,"one_line_summary":"For the tBESS vector resonance triplet with direct third-generation couplings, LHC mass exclusion limits require including bottom-quark partons in the production calculation, and the strongest limits push into the width region where the narrow-width approximation is no longer valid.","lead":"Researchers studied a hypothetical family of heavy particles that interact directly only with top and bottom quarks and asked what masses the LHC can rule out. They found that bottom quarks inside protons can dominate production of the neutral particle, so simplified estimates that ignore them are not reliable.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Updated mass limits rely on NWA at fatnesses 11–44%, so the quantitative exclusion limits are not established; the b-quark production claim itself is more robust.","rationale":"The reader's conditional verdict is the right call. The paper's own text supplies the limiting condition: the NWA is trusted only for Γ/Mρ≲10%, and the updated limits are all above this threshold. I nonetheless do not move to reject: the strongest qualitative claim, that b-quark partons materially alter neutral Drell-Yan production, is anchored at Mρ=1 TeV, g′′=20 where the resonance is narrow and the partial-width/luminosity argument is explicit; the broad-width problem is acknowledged, and the 'with caution' phrasing is an honest limitation rather than a hidden error; and the parameter-scan structure may still be useful as a case study if readers restrict themselves to the Γ/Mρ<10% subregions. The proposed test would replace the caveat with an actual width-valid recast; until then, the quantitative MELs should be regarded as indicative, which is exactly the conditional status the reader assigned.","tokens_in":28682,"tokens_out":16185,"duration_ms":152412,"concrete_test":"Recompute the g′′=20, bL=bR=0.1, p=1 exclusion limit from Table 7 (MEL=2.96 TeV, Γtot/Mρ=0.41) with a full Breit-Wigner line shape: evaluate pp→WW via the s-channel ρ0 with an exact propagator and off-shell kinematics, add DY and VBF amplitudes coherently, include signal-background interference for the qq→WW channel, and apply the same 36–139 fb−1 ATLAS/CMS WW selections used in Section 4.4. Compare the 95% CL excluded mass with the NWA value. If the shift exceeds roughly 0.1 TeV (the table step size), the NWA-based tables should not be used as quantitative limits without a width-valid recast.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The load-bearing weak point is Eq. (27), the NWA factorization σ=σprod×BR used for every quoted mass-exclusion limit. Section 3 states the approximation is expected to work for Γtot/Mρ ≲ 10%. The updated Tables 6–8 quote limits at fatnesses of 11%–44% (and >44% for g′′≤19/20): e.g., Table 7 has Γtot/Mρ=0.41 at Mρ=2.96 TeV for g′′=20, and Table 8 has 0.40 at 2.97 TeV. At those widths the on-shell/peak approximation misses off-shell production, which is enhanced by a broad propagator, and the ATLAS/CMS bounds themselves are derived with narrow-resonance signal templates; a caution note does not make the comparison quantitative. The Conclusions explicitly disclaim results above 10%, yet the numerical MELs are presented as the paper's main results. The qualitative b-quark claim is less exposed: the 95% b¯b→ρ0 contribution at Mρ=1 TeV, g′′=20 occurs at fatness well below 10%, and it is supported by partial-width/PDF-luminosity ratios. Thus the central conceptual conclusion—b-partons cannot be dropped—survives; the quantitative limits do not.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper studies mass exclusion limits for a strongly coupled composite SU(2)_L+R vector resonance triplet (the tBESS model) with direct couplings to the third quark generation only. Using LHC upper bounds on σ×BR and the narrow width approximation (NWA), the authors compute exclusion limits for the neutral and charged resonances, updating earlier work by including sea-quark (including bottom) parton densities and new ATLAS/CMS data. The central qualitative result is that b-quark partons cannot be neglected in the neutral Drell-Yan production: for e.g. Mρ=1 TeV, g''=20, bL=bR=0.1, p=1, the bbar→ρ0 contribution is 95%. The paper also presents updated mass exclusion limits in Tables 6-8, where the resonance fatness Γtot/Mρ ranges from 11% to over 40%, and includes a discussion of flavor physics constraints on the direct couplings. The authors are candid that the NWA is unreliable above Γtot/Mρ≈10% and that the quoted high-fatness limits must be considered with caution.","tokens_in":28992,"tokens_out":5924,"duration_ms":58427,"significance":"If the b-quark dominance claim holds, the paper makes a useful and non-obvious point: direct couplings to the third generation can compensate the small b-quark parton luminosity, so phenomenological recasts of LHC resonance searches that drop b-quark initial states can be qualitatively wrong. The analytic partial-width formulas, the explicit luminosity treatment with CT10 PDFs, and the systematic scanning of bL, bR, and p are clear strengths, and the authors openly flag the limitations of their approximations. The weakness is that the headline numerical mass exclusion limits (Tables 6-8) are all derived in the regime where the NWA is acknowledged to be unreliable, so the quantitative limits are not established even though the qualitative conclusion is likely robust. The paper is best viewed as a methodology case study with a robust qualitative message, not as a source of final exclusion numbers.","major_comments":[{"comment":"The updated mass exclusion limits are obtained from the NWA factorization σ=σprod×BR, which the paper itself expects to be valid only for Γtot/Mρ ≲ 10%. Tables 6-8 quote limits at fatnesses from 0.11 to above 0.44; for example, Table 7 lists Γtot/Mρ=0.41 at MEL=2.96 TeV for g''=20, and Table 8 lists 0.40 at 2.97 TeV. At such widths, off-shell production, line-shape effects, and signal-background interference are not negligible, and the caution in Section 5 does not turn these numbers into reliable predictions. The quantitative central claim of the paper is therefore not supported. I recommend either restricting all quoted MELs to the region Γtot/Mρ ≤ 0.10, or providing a finite-width/off-shell calculation that accounts for the propagation and interference effects, or explicitly presenting the high-fatness numbers only as an illustrative extrapolation.","section":"3, Eq. (27); Tables 6-8; Section 5"},{"comment":"The comparison of model predictions with ATLAS and CMS upper bounds inherits the experimental analyses' own narrow-resonance assumptions. The Collaborations' signal templates used to derive the 95% CL bounds in Refs. [39-61] are constructed for narrow line shapes; for a resonance with Γtot/Mρ>20%, the acceptance, efficiency, and the very definition of the on-shell cross section differ from what the NWA predicts. The manuscript does not quantify this systematic mismatch, and merely noting that the limits are 'based on the narrow resonance qualification' is insufficient. This is a separate, load-bearing issue from the theoretical NWA validity, and it affects the numerical MELs even if the NWA were replaced by a more accurate production calculation.","section":"4.4 and Section 4.1; experimental bounds"},{"comment":"The Conclusions present the updated numerical MELs as the main results (e.g., limits between 2.28 TeV and 2.97 TeV with fatnesses 11-40%) and only then state that these values 'must be considered with caution'. Because the fatness exceeds the paper's own 10% rule by a large margin, the text should clearly separate the region where the NWA-based limits are reliable from the region where they are not. As written, a reader can easily take the tables to be actual exclusion bounds rather than a demonstration of where the procedure breaks down. A re-framing that makes the methodology-caution message primary would resolve this.","section":"Conclusions, Tables 6-8"}],"minor_comments":[{"comment":"The caption says 'within the interval |bL=R| ≤ 1', but the model parameter space and the surrounding text restrict |bL,R| to ≤0.1. This looks like a typo and should be corrected to |bL=R| ≤ 0.1 to avoid confusion.","section":"Table 4 caption"},{"comment":"The text says 'we restrain ourselves from displaying the mass exclusion limits when they exceed 3 TeV', yet Tables 6-8 quote '> 3 TeV' entries for several g'' values. This is a verbal-logical mismatch; please clarify that limits above 3 TeV are expressed only as a lower bound and are not numerically resolved.","section":"Section 4.4"},{"comment":"The legend labels 'WL+ZL' and 'WL-ZL' are ambiguous; they presumably denote the luminosities for W_L Z_L and W_L W_L (or the like) in the VBF contribution. Please use explicit particle names for clarity.","section":"Figure 6"},{"comment":"The phrase 'the sea-without-b quark production' is awkward; consider replacing with 'the production of all sea quarks except the bottom quark'.","section":"Section 3.1"},{"comment":"The sentence 'Their validity are also limited by the assumptions and approximations applied to their calculations' contains a subject-verb agreement error; 'validity are' should be 'validity is'.","section":"Abstract"}],"recommendation":"major_revision","confidential_remarks":"The paper is honest and internally consistent about its approximations, and the qualitative conclusion about b-quark partons is likely correct and useful for the reinterpretation community. The main obstacle to acceptance is that the numerical limits in Tables 6-8 are presented as results even though the authors themselves state that the NWA is not reliable for those fatnesses. If the manuscript is revised to make the reliable region primary and to treat the high-fatness numbers as an illustration (or, ideally, to include a finite-width treatment), it would be a solid contribution. The apparent '≤1' typo in Table 4 is easily fixed. No concerns about novelty disclosure or citation patterns."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Two things to know about this one. The central qualitative claim—that b-quark partons cannot be ignored when a vector triplet has direct couplings to the third generation—is solid. The paper shows with explicit numbers that at Mρ=1 TeV, g''=20, bL=bR=0.1, p=1, bb→ρ0 makes up 95% of neutral DY production, and the partial-width and PDF-luminosity arguments support it. That is a real correction to the authors' earlier no-direct-coupling paper, and it is the main reason to read this.\n\nThe updated numerical mass exclusion limits, however, are not established. The paper itself says the NWA is expected to work for Γtot/Mρ ≲ 10%, and the updated Tables 6–8 quote limits at fatnesses of 11–44% (and above 44% for g''≤19/20). At those widths, off-shell production and signal-background interference are not negligible, and the ATLAS/CMS bounds are derived with narrow-resonance templates. The Conclusions explicitly caution against relying on results above the 10% mark, yet those same numbers are the paper's headline output. That tension is the paper's soft underbelly—not a fatal flaw, since the qualitative lesson survives, but the quoted limits should be treated as provisional until re-evaluated with a method that handles broad widths.\n\nWhat the paper does well: the cross-section framework is laid out carefully, with analytic partial widths, the luminosity machinery, and the distinction between DY and VBF modes. The exclusion maps in the (bL,bR) plane (e.g., Fig. 11) are a nice way to show how the direct couplings reshape the excluded region. The authors are honest about the NWA caveat and about the limitations of their flavor-physics discussion; they do not oversell.\n\nMinor soft spots: no uncertainty estimates on the limits; only one PDF set (CT10) and one scale choice, so the b-dominance has not been stress-tested against, say, NNPDF or a scale variation. The flavor constraints on bL,bR require assumptions about the λL,λR parameters; the paper acknowledges this, but it means the 'consistent' low-energy limits are not a sharp cross-check. These are minor relative to the NWA issue.\n\nWho is this for? Phenomenologists working on composite or third-generation-coupled resonances at the LHC. It deserves a serious referee: the central claim is worth checking, and a referee could ask for a width-corrected limit analysis as a condition for the numerical parts. I'd bring it to a reading group for the b-quark lesson, though I probably wouldn't cite it in my own work.","headline":"The b-quark dominance claim is solid and this paper's main contribution; its updated mass limits outrun the NWA validity the authors themselves set, so treat the numbers as provisional.","tokens_in":29514,"tokens_out":2523,"would_cite":false,"duration_ms":23390,"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":"Bottom-quark annihilation can dominate production of a new heavy neutral boson, so it controls the LHC mass limits.","keywords":["tBESS model","vector resonance triplet","mass exclusion limits","bottom quark parton distribution","Drell-Yan production","narrow width approximation","third generation couplings","LHC resonance searches"],"falsifier":"Compute the full off-shell $pp\\to W^+W^-$ cross section with the complete propagator of the broad $\\rho^0$ and with signal-background interference included, for example at $g''=20$, $M_\\rho=1.8$ TeV, $b_L=b_R=0.1$, $p=1$. If the full result differs from the narrow-width value by more than the experimental uncertainty, or if the full calculation moves the excluded-region boundary in the $(b_L,b_R)$ plane, then the NWA-based exclusion limits are not reliable for those parameters.","tokens_in":28469,"feed_emoji":"⚛️","tokens_out":13387,"duration_ms":123420,"temperature":0.7,"pith_summary":"This paper argues that when a new heavy vector boson couples directly to the third quark generation, the standard shortcut of dropping bottom quarks from the proton's parton content fails. In the tBESS model studied here, the neutral resonance's Drell-Yan production can be dominated by $b\\bar{b}$ annihilation: in one benchmark with resonance mass 1 TeV, $g''=20$, $b_L=b_R=0.1$, and $p=1$, the $b\\bar{b}\\to\\rho^0$ subprocess supplies 95% of the production cross section despite the bottom quark's tiny parton density. Because every neutral decay channel inherits this production, the LHC mass exclusion limits for the resonance, including the $WW$ channel, depend on the direct bottom couplings; ignoring bottom quarks changes the limits qualitatively. The paper also finds that updated LHC bounds push the exclusion limits beyond 3 TeV for weaker resonance couplings, but at those masses the resonance width is so large that the narrow width approximation used to derive the limits is no longer clearly valid.","feed_headline":"Bottom-quark partons can supply 95% of new-boson production","feed_subtitle":"A study of third-generation-coupled resonances finds that LHC mass limits cannot ignore b-quark partons.","key_machinery":"The load-bearing object is the effective-Lagrangian vector triplet introduced via hidden local symmetry, with direct couplings $b_L$, $b_R$, and $p$ to the third-generation quarks. The cross section is assembled from the narrow width formula $\\sigma(pp\\to abX)=\\sigma_{\\rm prod}(pp\\to\\rho X)\\times{\\rm BR}(\\rho\\to ab)$, where the production cross section is a sum over parton channels of $16\\pi^2 K_{AB}F_{AB}\\,d\\Pi_{AB}/d\\hat{s}$ evaluated at $\\hat{s}=M_\\rho^2$. The decisive factor is the partial fatness $F_{AB}=\\Gamma_{\\rho\\to AB}/M_\\rho$: the $b\\bar{b}$ partial fatness is the only DY entry that grows with the direct couplings, and this is what allows the tiny $b\\bar{b}$ quasi-luminosity to win. This mechanism, not an exotic PDF feature, carries the argument that bottom-quark partons must be included.","core_discovery":"The central claim is that for an $SU(2)_{L+R}$ vector resonance triplet coupled directly and only to top and bottom quarks, bottom-quark partons cannot be dropped from neutral-resonance production. The partial fatness $F_{bb}$ is the only Drell-Yan entry that grows with the direct couplings, scaling as $g''^2(b_L^2+p^4 b_R^2)$ while all other Drell-Yan fatnesses fall as $1/g''^2$; this overcomes the 2--3 order-of-magnitude deficit of the $b\\bar{b}$ parton luminosity. With $M_\\rho=1$ TeV, $g''=20$, $b_L=b_R=0.1$, $p=1$, the $b\\bar{b}\\to\\rho^0$ contribution is 95% of neutral DY production, and the paper states there are parameter regions where more than 90% of neutral resonance production proceeds through $b\\bar{b}\\to\\rho^0$. The $WW$ and $WZ$ channels remain the only ones that exclude the triplet, and their limits now extend past 3 TeV for the weakest couplings in the considered range, with resonance fatness above 40%; the paper explicitly cautions that such limits rest on the narrow width approximation beyond its expected range of validity.","pith_inferences":["Editorial inference: the same $b\\bar{b}$-dominance mechanism should appear in any $Z'$-like or composite vector model with enhanced bottom couplings, so the lesson extends beyond tBESS to composite-Higgs and partial-compositeness parameter regions.","Editorial inference: the sharp change in excluded regions between $M_\\rho=1.75$ and $1.85$ TeV seen in the paper suggests that coarse mass grids in limit reinterpretations could miss narrow allowed windows; fine mass scans are needed.","Editorial inference: because the updated excluded regions concern broad resonances, a full off-shell calculation including signal-background interference could shift the boundaries; this is a direct, testable extension of the paper's NWA-based limits.","Editorial inference: future LHC searches for strongly coupled resonances may need to use broad line-shape templates instead of narrow-peak searches, since the width-to-mass ratio grows quickly with the resonance mass."],"forward_implications":["Reinterpretations of LHC neutral-resonance limits in models with enhanced third-generation couplings must include $b$-quark parton distribution functions in the production calculation.","The $WW$ and $WZ$ channels are the only current sources of mass exclusion limits for the tBESS triplet; the $tt$, $bb$, and $tb$ channels do not yet reach the experimental upper bounds.","In the $(b_L,b_R)$ plane the excluded region can be ring-shaped, with a central allowed island, so limits on the direct couplings are highly mass- and $p$-dependent.","Updated LHC bounds raise the exclusion limits past 3 TeV for weaker couplings, but the corresponding width-to-mass ratios exceed 10% (up to about 44%), so those numerical limits should be treated with caution.","Flavor-physics restrictions from $Z\\to b\\bar{b}$ and $B\\to X_s\\gamma$ are consistent with the LHC-derived limits on $b_L$ and $b_R$ and can complement them once the auxiliary $\\lambda$ parameters are fixed."],"supporting_citations":[{"why":"Defines the tBESS effective Lagrangian and the direct $b_L,b_R,p$ couplings to the third-generation quarks that generate the $b\\bar{b}$ production term.","marker":"[16]"},{"why":"Previous mass-exclusion analysis of the same model without direct fermion couplings; it supplies the baseline that this paper upgrades by adding sea quarks.","marker":"[19]"},{"why":"Analysis of narrow width approximation accuracy including signal-background interference; it motivates the 10% fatness rule used to judge the limits.","marker":"[35]"},{"why":"Provides the WZ Drell-Yan and VBF upper bounds used to set the neutral and charged resonance mass limits.","marker":"[39]"},{"why":"Provides the jj upper bounds for WW and WZ that restrict the hadronic final states.","marker":"[41]"},{"why":"Provides the WW upper bound in the lnuqq final state used in the updated mass exclusion limits.","marker":"[43]"},{"why":"Provides the tt upper bound that is compared and found not to exclude the triplet at current luminosity.","marker":"[51]"},{"why":"Provides the bb upper bound used to show the bb channel does not yet restrict the resonance.","marker":"[52]"},{"why":"Provides the tb upper bound used to show the tb channel does not yet exclude the triplet.","marker":"[53]"}],"fun_headline_variants":["b-quark partons can fuel 95% of new-boson production","b-quark fusion can drive neutral resonance production","Mass limits for new resonances hinge on bottom quarks","Bottom-quark partons tip LHC mass limits","Including b-quarks changes resonance exclusions"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The numerical limits assume that a broad resonance can still be treated as if it decays on-shell, and the paper itself doubts this once the width exceeds about 10% of the mass; several updated limits sit at 11-44%.","fun_headline_variants_meta":{"raw":{"variants":["b-quark partons can fuel 95% of new-boson production","b-quark fusion can drive neutral resonance production","Mass limits for new resonances hinge on bottom quarks","Bottom-quark partons tip LHC mass limits","Including b-quarks changes resonance exclusions"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000842,"raw_usage":{"total_tokens":3695,"prompt_tokens":1002,"completion_tokens":2693,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":618,"completion_tokens_details":{"reasoning_tokens":2612}},"tokens_in":618,"tokens_out":2693,"duration_ms":18869,"temperature":1.0,"reasoning_tokens":2612,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-14T10:09:30.965620+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Compute the full off-shell $pp\\to W^+W^-$ cross section with the complete propagator of the broad $\\rho^0$ and with signal-background interference included, for example at $g''=20$, $M_\\rho=1.8$ TeV, $b_L=b_R=0.1$, $p=1$. If the full result differs from the narrow-width value by more than the experimental uncertainty, or if the full calculation moves the excluded-region boundary in the $(b_L,b_R)$ plane, then the NWA-based exclusion limits are not reliable for those parameters.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Provides the jj upper bounds for WW and WZ that restrict the hadronic final states."},{"cited_title":"Gintner, J","cited_arxiv_id":null,"evidence_quote":"Defines the tBESS effective Lagrangian and the direct $b_L,b_R,p$ couplings to the third-generation quarks that generate the $b\\bar{b}$ production term."},{"cited_title":"The LHC mass limits for the $SU(2)_{L+R}$ vector resonance triplet of a strong extension of the Standard model","cited_arxiv_id":"1705.04806","evidence_quote":"Previous mass-exclusion analysis of the same model without direct fermion couplings; it supplies the baseline that this paper upgrades by adding sea quarks."},{"cited_title":"https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT- 2017-31/","cited_arxiv_id":null,"evidence_quote":"Provides the WZ Drell-Yan and VBF upper bounds used to set the neutral and charged resonance mass limits."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Provides the WW upper bound in the lnuqq final state used in the updated mass exclusion limits."},{"cited_title":"Search for vector-boson resonances decaying to a top quark and bottom quark in the lepton plus jets final state in $pp$ collisions at $\\sqrt{s}$ = 13 TeV with the ATLAS detector","cited_arxiv_id":"1807.10473","evidence_quote":"Provides the tb upper bound used to show the tb channel does not yet exclude the triplet."}],"review_version":1}