{"id":"6be5acfd-c783-49e3-a1e0-492fb352fbba","arxiv_id":"2412.19445","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"A detector-level Monte Carlo study finds that pair-produced E6SSM scalar diquarks decaying to top-bottom pairs could be observed with >3 sigma statistical significance at the HL-LHC for masses up to 900 GeV.","lead":"The authors simulated a hypothetical particle called a diquark, predicted by a supersymmetric extension of the Standard Model, and computed how often the Large Hadron Collider would see it decaying into top and bottom quark pairs. They find the upgraded HL-LHC could reach a 3-sigma statistical signal for such a diquark with mass up to about 900 GeV, giving experimentalists a concrete search channel.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The abstract's 'up to 1 TeV' reach is not supported by the paper's own cut-flow: for mD=1000 GeV, the tabulated yield gives only about 2 sigma at 3000 fb^-1, not >3 sigma.","rationale":"The reader's weakest_assumption concerns the BR~1 model-parameter choice, which is a legitimate conditionality but is internally consistent with the stated couplings. My stress-test identifies a more direct and numerically checkable problem: the paper's own Table 5 appears to exclude the 1 TeV mass point from the claimed >3 sigma HL-LHC reach. This supports the reader's CONDITIONAL verdict and reinforces the need to correct the abstract and conclusions. The analysis remains a plausible detector-level projection for mD up to about 900 GeV, using statistical significance only, provided the K-factors are applied consistently. I therefore do not move the verdict away from CONDITIONAL, but the correction is necessary before the paper is used as a search target.","tokens_in":12061,"tokens_out":8789,"duration_ms":89166,"concrete_test":"Recompute the 3000 fb^-1 significance for mD=1000 GeV from the fat-jet cut-flow in Table 5, using the authors' K-factors: take S=5, B=117 at 140 fb^-1 (or the K-factor-adjusted values if provided) and scale by sqrt(3000/140). If the result is below 3 sigma, the abstract and conclusions should be corrected to claim reach only up to about 900 GeV. Also recompute the 900 GeV point in the same way to verify whether it actually exceeds 3 sigma after K-factors.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The most load-bearing problem is not the BR(D->tb)~1 tuning (which is an explicit model assumption) but the fact that the headline reach is contradicted by the paper's own event counts. In the fat-jet analysis at 140 fb^-1 (Table 5), the final pbT cut leaves 5 signal events for mD=1000 GeV against 117 background events (ttbb 5 + ttjj 112). The statistical significance at 140 fb^-1 is therefore S/sqrt(B) = 5/sqrt(117) = 0.46 sigma; scaling to 3000 fb^-1 by sqrt(3000/140) ~ 4.63 gives about 2.1 sigma, below the claimed 3 sigma. The same table gives about 3.0 sigma for 900 GeV (7 events vs 117) before K-factors. Unless the K-factors, which the paper does not tabulate for this channel, raise the 1000 GeV point by more than a factor of about 1.4, the abstract's 'up to 1 TeV' claim is unsupported. The central claim should be restated as 'up to about 900 GeV, statistical significance only.'","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper studies the phenomenology of the lightest S4-type scalar diquark D predicted by the E6SSM, focusing on pair production at the LHC with D decaying to tb pairs. The authors generate signal and background events with MadGraph/Pythia/Delphes, apply a resolved analysis and a fat-jet analysis, and derive signal significances at 140, 300, and 3000 fb^-1. They also reinterpret ATLAS and CMS charged-Higgs searches to set an exclusion limit on mD. The central claim in the abstract and conclusions is that the HL-LHC can reach a statistical significance exceeding 3 sigma for diquark masses up to 1 TeV.","tokens_in":12431,"tokens_out":3756,"duration_ms":36046,"significance":"If the result holds, this would be a useful, detector-level study of a previously under-explored channel: pair production of E6SSM scalar diquarks in the t tbar b bbar final state with one lepton. The paper uses standard modern tools, provides cut-flow tables and mass distributions, and explicitly compares with existing LHC searches, which are all positive features. The analysis is a forward Monte Carlo simulation with free input masses and couplings, so there is no circularity. The main significance is in establishing that a 900 GeV diquark with BR(D->tb)~1 could be observable at the HL-LHC with statistical significance around 3 sigma, and in identifying the boosted fat-jet selection as the relevant strategy for the upper end of the mass range.","major_comments":[{"comment":"The headline claim that the HL-LHC reach exceeds 3 sigma for masses 'up to 1 TeV' is contradicted by the paper's own cut-flow. In Table 5, for mD = 1000 GeV the final selection at 140 fb^-1 leaves 5 signal events against 117 background events (ttbb 5 + ttjj 112). Statistical significance, NS/sqrt(NB), is therefore 5/sqrt(117) = 0.46 sigma at 140 fb^-1; scaling by sqrt(3000/140) = 4.63 gives about 2.1 sigma at 3000 fb^-1, not above 3 sigma. The same table gives 7 signal events for mD = 900 GeV, corresponding to 7/sqrt(117) = 0.65 sigma at 140 fb^-1 and about 3.0 sigma at 3000 fb^-1 before K-factors. The abstract and Section 5 should be corrected to state that the 3-sigma reach applies at most to about 900 GeV, not 1 TeV, for the statistical-only significance defined in the paper.","section":"Abstract and Sec. 5 (also Table 5 and Fig. 5)"},{"comment":"The K-factors used for the fat-jet significances are not specified. The only description appears in Sec. 4.1, where K-factors from Refs. [26] and [46] are mentioned, but no values are given and it is not stated whether the same K-factors are applied to the signal and to each background in the fat-jet analysis. This matters because the 900 GeV point is borderline: without K-factors it gives about 3.0 sigma at 3000 fb^-1, and the claim of 'above 3 sigma' depends on the size and treatment of the K-factors. Please tabulate the K-factors used, justify their application to this final state, and show the significance with and without them. In addition, the significance definition NS/sqrt(NB) includes no systematic uncertainties; at NS=7 and NB=117, even a modest systematic uncertainty on the background would reduce the quoted reach.","section":"Sec. 4.2 and Fig. 5"},{"comment":"The exclusion limit on mD is derived by intersecting the predicted t tbar b bbar cross section from D Dbar production with ATLAS and CMS H^+- -> tb search contours. This reinterpretation assumes that the experimental acceptance, selection efficiencies, and background composition for the charged-Higgs signal apply to the diquark pair-production signal. That assumption is not demonstrated. Since the '~600 GeV' exclusion is used to justify focusing on mD = 700 GeV and above, the authors should either validate the reinterpretation with a more detailed efficiency map or clearly label the limit as approximate and model-dependent.","section":"Sec. 3 and Fig. 2"},{"comment":"The benchmark scenario assumes BR(D -> tb) = BR(anti D -> tbar bbar) = 1, obtained by setting O(10^-3) couplings to third-generation quarks and vanishing couplings to first- and second-generation quarks. This is an input assumption, not a derived prediction. The quoted discovery reach scales with the square of this branching fraction, so the abstract and conclusions should explicitly state that the 3-sigma reach holds only under this BR=1 assumption. The paper does state the assumption in Sec. 3, but the abstract and conclusions present the reach without this caveat, which is misleading.","section":"Sec. 3, first paragraph"}],"minor_comments":[{"comment":"In the sentence 'individual jets and leptons will can no longer be resolved', 'will can' should be corrected to 'can'. Additionally, please define P_H^T more precisely than 'total hadronic transverse energy'; specify the sum over which objects and how the 1400 GeV requirement was chosen.","section":"Sec. 4.2"},{"comment":"Equation (2) and the surrounding text refer to 'B + L1', which appears to be a typesetting issue for 'B + L'. Please clarify that the first term preserves B+L and the second violates B+L.","section":"Sec. 2"},{"comment":"Figure 5 does not display the numerical significance values; since the abstract claims a 1 TeV reach, the figure should explicitly mark the mD = 1000 GeV point and the 3-sigma line so the reader can see the tension with the abstract.","section":"Fig. 5"},{"comment":"The phrase 'fairly light (up to 1 TeV) D' is inconsistent with the paper's own analysis, which does not demonstrate sensitivity at 1 TeV; consider replacing 'up to 1 TeV' with 'up to about 900 GeV' throughout the conclusions.","section":"Sec. 5"}],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"You should know two things before reading this paper. First, the central analysis is a competent, standard MC study of E6SSM scalar diquark pair production in the t tbar b bbar final state, with a sensible boosted-tagging strategy for higher masses. Second, the abstract's headline claim—'>3 sigma at the HL-LHC for diquark masses up to 1 TeV'—is not supported by the paper's own numbers. From Table 5, the 1000 GeV point has 5 signal events versus 117 background at 140/fb, giving S/sqrt(B) of 0.46; scaling to 3000/fb gives about 2.1 sigma. Only the 900 GeV point reaches about 3 sigma. The text in Section 5 correctly says 'above 3 sigma' for 900 GeV, so the abstract overstates the reach by about 100 GeV.\n\nWhat is genuinely new: the specific E6SSM S4 diquark interpretation, the detector-level reconstruction of D Dbar -> t tbar b bbar using fat jets, and the quantitative sensitivity estimate for 700–1000 GeV. The methods are standard (MadGraph/Pythia/Delphes/MadAnalysis) and the cut-flow is transparent. The paper does not generate its own cross sections from a fitted parameter; it uses external K-factors and experimental limits, so there is no circularity in the significance estimate.\n\nThe soft spots are proportionate. The novelty claim is overstated: pair production of scalar diquarks was already studied in Refs [25,26] (Chen et al., Han et al.), so the statement that pair production is 'largely unexplored' is inaccurate. The significance includes only statistical uncertainties; any systematic on b-tagging or jet scale could shift the 900 GeV point. The reinterpretation of the H+ searches as exclusions on mD is crude—it simply compares total cross sections—but it is a reasonable first pass. The assumption of BR(D->tb)=1 requires specific Yukawa parameters, which the paper states clearly; that is an assumption, not an error.\n\nOverall, this is a useful search strategy for a specific model, with one fixable but important internal inconsistency. I would send it to peer review, because the analysis for 900 GeV is sound and the errors are in presentation rather than method. After revision—correct the abstract, revise the novelty claim, and add a note on systematics—it could be a citable reference for E6SSM diquark searches.","headline":"Useful MC search projection, but the 'up to 1 TeV' claim is contradicted by the paper's own Table 5; the defensible reach is ~900 GeV.","tokens_in":12904,"tokens_out":5141,"would_cite":true,"duration_ms":43174,"reading_group":"maybe","serious_thinker":"no","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"The paper claims that a sub-TeV scalar diquark of the E6SSM can be discovered at the HL-LHC in the ttbb final state, with statistical significance exceeding 3 sigma for masses up to 1 TeV.","keywords":["scalar diquark","E6SSM","diquark pair production","top-bottom decay","HL-LHC search","fat jets","b-jet tagging","beyond Standard Model"],"falsifier":"Reconstruct the same $t\\bar{t}b\\bar{b}$ final state at the HL-LHC with 3000 fb$^{-1}$ and look at the diquark mass window near 900 GeV; if the event count matches the Standard Model background within statistical fluctuations, the paper's claimed $>3\\sigma$ significance for a 900 GeV diquark is ruled out for that scenario.","tokens_in":11896,"feed_emoji":"⚛️","tokens_out":8450,"duration_ms":68052,"temperature":0.7,"pith_summary":"This paper argues that the lightest scalar diquark predicted by the E6SSM could be discovered at the High-Luminosity LHC. The relevant particle, of a type called S4, would be produced in pairs by QCD and would decay almost exclusively to top-bottom pairs, leaving a final state of two top quarks and two bottom quarks. The authors simulate this signal against Standard Model backgrounds and find that with 3000 inverse femtobarns the statistical significance exceeds 3 sigma for diquark masses up to about 1 TeV. They also show that present LHC data already exclude masses below roughly 600 GeV for their benchmark parameters. A reader should care because this gives the LHC a concrete, testable signature for a motivated beyond-Standard-Model particle.","feed_headline":"A scalar diquark could show up at the HL-LHC with 3-sigma reach","feed_subtitle":"Pair-produced E6SSM diquarks decaying to top-bottom pairs would exceed 3 sigma up to about 1 TeV with 3000 fb^-1.","key_machinery":"The central object is the S4 diquark, a color anti-triplet scalar with hypercharge $+1/3$ that couples two same-chirality quarks. In the E6SSM its couplings are naturally small and dominated by the third generation, so with the chosen parameters the branching ratio $D \\to tb$ is effectively one. The mechanism carrying the argument is QCD pair production followed by the reconstruction of two top quarks and two bottom quarks: one analysis resolves individual jets, and a second, for higher masses, reconstructs each top as a single anti-$k_t$ fat jet with radius 0.8 and pairs the fat jets with the two leading $b$-jets. The statistical significance $N_S/\\sqrt{N_B}$ after these cuts is what grows with integrated luminosity to cross the $3\\sigma$ threshold.","core_discovery":"The central claim is that pair production of the lightest S4-type scalar diquark $D$, with mass below 1 TeV and branching fraction close to one into $tb$, is discoverable at the HL-LHC through the process $p p \\to D \\bar{D} \\to (\\bar{t} \\bar{b})(t b)$. With one top decaying leptonically and the other hadronically, the signature is four $b$-jets, two light jets, one lepton and missing transverse momentum. Using a boosted analysis in which each top is reconstructed as a fat jet, the paper finds statistical significance above $3\\sigma$ for a 900 GeV diquark and larger significance for 700-800 GeV at 3000 fb$^{-1}$, while the resolved-jet analysis reaches $5\\sigma$ only for masses up to 600 GeV. The result depends on choosing E6SSM parameters for which the diquark has $O(10^{-3})$ couplings to third-generation quarks and negligible couplings to lighter generations.","pith_inferences":["If such a diquark is observed, its production rate could be used to extract the diquark Yukawa couplings to the third generation, assuming the mass is measured from the reconstructed peak.","The same $t\\bar{t}b\\bar{b}$ search strategy could be applied to color-triplet scalar diquarks in other models, such as Pati-Salam or R-parity-violating supersymmetry, where the decay to $tb$ may also dominate.","The quoted significance is statistical only; including systematic uncertainties in tagging and jet energy scales would lower it, so the actual discovery reach in mass is likely somewhat below 1 TeV.","A natural follow-up would be to search for single-diquark production through $tb$ fusion, which becomes visible if first- or second-generation couplings are not exactly zero and would complement the pair-production channel."],"forward_implications":["At 3000 fb$^{-1}$, the HL-LHC would see a $>3\\sigma$ excess for diquark masses up to about 1 TeV in the $t\\bar{t}b\\bar{b}$ channel.","Masses below about 600 GeV are already excluded by existing $tb$ resonance searches for the benchmark scenario.","The boosted fat-jet reconstruction is necessary for diquarks heavier than roughly 700 GeV, where resolved jets fail.","If the signal is absent at the HL-LHC, the E6SSM diquark interpretation with $\\mathrm{BR}(D \\to tb) \\simeq 1$ is constrained up to 1 TeV.","The same event selection provides a mass reconstruction of the diquark pair, though with wide distributions that would make a precise mass measurement difficult."],"supporting_citations":[{"why":"Supplies the NLO QCD corrections and K-factors used for the diquark pair-production signal cross section.","marker":"[26]"},{"why":"Defines the E6SSM and its diquark sector, the model whose lightest S4 diquark is studied.","marker":"[28]"},{"why":"Generates the leading-order signal and background events for the Monte Carlo analysis.","marker":"[31]"},{"why":"Provides the LHC exclusion contour for $tb$ resonances used to set the diquark mass limit.","marker":"[33]"},{"why":"Provides the stronger all-jet search limit that excludes diquark masses below about 600 GeV.","marker":"[34]"},{"why":"Performs parton showering and hadronization on the generated events.","marker":"[41]"},{"why":"Emulates the detector response for the reconstructed final state.","marker":"[42]"},{"why":"Provides the anti-$k_t$ jet clustering algorithm used for both resolved and fat-jet reconstruction.","marker":"[43]"},{"why":"Supplies the background K-factors used in computing the signal significances.","marker":"[46]"}],"fun_headline_variants":["HL-LHC could detect E6SSM diquark up to 1 TeV","E6SSM diquark pair production: 3σ at HL-LHC to 1 TeV","Scalar diquark from E6SSM: HL-LHC sees >3σ up to 1 TeV","Diquark discovery potential at HL-LHC: >3σ for masses to 1 TeV"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The result assumes the diquark decays essentially 100% of the time to a top and a bottom quark, which requires its couplings to third-generation quarks to be about $10^{-3}$ and its couplings to first- and second-generation quarks to vanish exactly; if those conditions fail, the branching fraction and the computed significance drop.","fun_headline_variants_meta":{"raw":{"variants":["HL-LHC could detect E6SSM diquark up to 1 TeV","E6SSM diquark pair production: 3σ at HL-LHC to 1 TeV","Scalar diquark from E6SSM: HL-LHC sees >3σ up to 1 TeV","Diquark discovery potential at HL-LHC: >3σ for masses to 1 TeV"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000243,"raw_usage":{"total_tokens":1558,"prompt_tokens":1007,"completion_tokens":551,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":623,"completion_tokens_details":{"reasoning_tokens":444}},"tokens_in":623,"tokens_out":551,"duration_ms":4638,"temperature":1.0,"reasoning_tokens":444,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-11T00:35:19.271665+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Reconstruct the same $t\\bar{t}b\\bar{b}$ final state at the HL-LHC with 3000 fb$^{-1}$ and look at the diquark mass window near 900 GeV; if the event count matches the Standard Model background within statistical fluctuations, the paper's claimed $>3\\sigma$ significance for a 900 GeV diquark is ruled out for that scenario.","supporting_citations":[],"review_version":1}