{"id":"7da4140e-f2eb-4db1-a789-dfc152421c62","arxiv_id":"1908.11859","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"Using boosted top tagging in a four-top final state, the first Kaluza-Klein Higgs excitation in the deformed Randall-Sundrum model could be probed up to about 1.2 TeV at the high-luminosity LHC, at the 3-sigma level.","lead":"This paper designs a search strategy for the first Kaluza-Klein Higgs boson in a warped extra dimension model, using a four-top-quark final state with two boosted tops. It estimates that such a particle up to about 1.2 TeV could be seen at the planned high-luminosity LHC, which tells experimentalists which channel to watch.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Table 3 reach is a generator-level S/sqrt(B) projection; with post-cut S/B ≈ 0.12, unquantified detector and systematic effects can move the 1.2 TeV 3σ luminosity above the 3000 fb^-1 HL-LHC target.","rationale":"The reader's weakest assumption identifies two issues: unspecified deformed-RS parameters from Ref. [10] and the lack of detector/systematic treatment. I concentrate on the second because the first merely rescales the signal, whereas the second interacts with the small S/B of this search: at the quoted luminosity the background counts are large enough that even modest systematics dominate the uncertainty. This is not a disagreement with the parton-level cut flow, whose arithmetic is internally consistent; it is a statement that the reach claim is not yet demonstrated. The proposed Delphes plus systematics rerun settles it. I therefore keep the reader's CONDITIONAL verdict: the paper is a useful strategy, but the headline 'explorable up to 1.2 TeV' should be read as conditional on detector and systematic effects being under control, which the paper does not quantify.","tokens_in":6206,"tokens_out":7389,"duration_ms":68567,"concrete_test":"Recompute the M_H1=1.2 TeV row of Table 3 using a fast detector simulation (e.g., Delphes with an ATLAS-like or CMS-like card, b-tag efficiency about 70%, mistag rate about 1%) and add a log-normal background systematic of 5% and 10% in the significance formula S/sqrt(B+sigma_B^2). If the 3-sigma luminosity exceeds 3000 fb^-1 for either systematic value, the paper's central explorability claim fails; if it remains below 3000 fb^-1, the concern is resolved.","verdict_should_be":"UNCHANGED","load_bearing_attack":"Table 3 is computed as generator-level S/sqrt(B), with no detector response and no systematic uncertainties. For M_H1=1 TeV, the final cut flow gives S=0.09 fb and B=0.75 fb (SM tttt 0.25 fb plus ttbb 0.50 fb), so S/B=0.12. At the quoted 3-sigma luminosity of 819 fb^-1 this is about 74 signal and 614 background events; with only a 10% background normalization uncertainty the significance becomes 74/sqrt(614+61^2)≈1.1, and even 5% gives about 2.1. The same fragility scales the 1.2 TeV row, where 1443 fb^-1 is quoted. The analysis also assumes the Nbtags>=3 requirement without specifying b-tag efficiency or mistag rate, and Sec. 4 merely says the luminosity 'may increase a little.' Since the abstract's 'explorable up to about 1.2 TeV' is exactly the statement that 3-sigma is reached within 3000 fb^-1, this unquantified detector/systematic effect is load-bearing.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper proposes a search for the first Kaluza-Klein excitation of the Higgs boson (H1) in the deformed Randall-Sundrum model, in the associated production channel pp -> H1 t tbar with H1 -> t tbar, yielding a four-top final state with two boosted tops. Using MadGraph/Pythia/FastJet parton-level simulations, the authors select the all-hadronic and special semileptonic channels with a lepton veto, require Njets>=9, Nbtags>=3, HT>=1250 GeV, and a mass window around M_h1, then quote 3-sigma and 5-sigma integrated luminosities. For M_h1 = 1.2 TeV they quote 1443 fb^-1 for a 3-sigma result, concluding that H1 masses up to about 1.2 TeV may be explorable at the high-luminosity LHC.","tokens_in":6437,"tokens_out":5994,"duration_ms":49858,"significance":"If the reach estimate survived a full experimental treatment, this would be a useful first study of a difficult channel that complements existing gluon-fusion KK-Higgs searches and exploits the boosted-top signature. Strengths: the analysis is clearly described, uses standard public tools, and the cut-flow numbers in Tables 2 and 3 are internally consistent with a generator-level S/sqrt(B) estimate. However, the quantitative conclusion currently rests on parton-level signal and background rates, on unstated deformed-RS model parameters, and on an assumption that tagging, mistagging, and detector effects do not materially change the final yields. The significance is therefore moderate.","major_comments":[{"comment":"The quoted luminosities are pure S/sqrt(B) projections at generator level, with no detector simulation and no systematic uncertainties. For M_h1 = 1 TeV the final signal is 0.09 fb and the background is 0.75 fb; at the quoted 819 fb^-1 luminosity this is about 74 signal and 614 background events, and adding a 10% background normalization uncertainty reduces the significance to about 1.1 sigma (5% gives about 1.9 sigma). The same fragility applies to the 1.2 TeV row (1443 fb^-1), where a modest systematic error would push the required luminosity above the 3000 fb^-1 HL-LHC target. Because the central claim is exactly that 3-sigma is reached within 3000 fb^-1, this omission is load-bearing; the statement in Sec. 4 that the luminosity “may increase a little” does not quantify the effect.","section":"Sec. 4, Tables 2 and 3"},{"comment":"The signal is generated with a FeynRules model from Ref. [10], but the deformed-RS benchmark parameters (the metric deformation, the parameters setting M_h1 and the H1-t tbar coupling, and the resulting total production cross sections) are not stated anywhere in this paper. Tables 2 and 3 therefore cannot be reproduced or checked. Please provide the benchmark point and a pre-cut cross-section table for each quoted mass.","section":"Sec. 3, model input"},{"comment":"The analysis applies Nbtags>=3 and Nlepton=0 without specifying the b-tag efficiency, the mistag rate for light/gluon jets, or the lepton veto efficiency. The final background after all cuts is 0.75 fb for M_h1=1 TeV, so the reach is highly sensitive to how these efficiencies are modeled. Since the paper already acknowledges in Sec. 4 that mistagging can increase the required luminosity, a quantitative estimate, or an explicit statement that the b-tag requirement is truth-level, is needed before the reach claim can be considered robust.","section":"Sec. 3, Nbtags and Nlepton cuts"}],"minor_comments":[{"comment":"There are several typographical errors, including “upto” in the abstract and “greator”, “similiarly”, and “senario” in Sec. 3; the manuscript should be proofread.","section":"Throughout"},{"comment":"The Introduction says the results and conclusion are presented in Sections 3 and 4, but the paper has separate Sections 4 (Results) and 5 (Conclusion); the cross-references need to be corrected.","section":"Sec. 1 (Introduction)"},{"comment":"The text says the maximum HT cut “can be around 1200 GeV for Mh1=1TeV”, while Table 2 applies HT>=1250 GeV; this inconsistency should be resolved and the optimization described consistently.","section":"Sec. 3, HT cut"},{"comment":"Table 2 labels the second background as t¯t+b¯b, while the text and Table 1 use t¯tbb; the notation should be unified.","section":"Tables 1 and 2"}],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Colleague,\n\nWhat you should know first: the new thing here is the channel, not the method. The authors study pp→H1 ttbar with H1→ttbar in the deformed RS model, leaving a four-top final state where two tops are boosted. That specific production/decay combination had not been simulated before, and using boosted-top hadronic decays for mass reconstruction is a sensible strategy. The paper does it cleanly: parton-level MadGraph+Pythia, a sensible cut flow, and luminosities for 3 and 5 sigma. The arithmetic in Table 3 is consistent with a simple S/sqrt(B) estimate.\n\nThe soft spots are real and load-bearing. There is no detector simulation, no b-tag efficiency or mistag rate, and no systematic uncertainties. The stress-test arithmetic is right: at M_H1=1 TeV after cuts, S/B≈0.12, so a 10% background normalization uncertainty drops the significance from 3σ to about 1σ, and even 5% gives about 2σ. That puts the central statement, 'explorable up to about 1.2 TeV at HL-LHC,' on shaky ground. The paper's own sentence that luminosities 'may increase a little' understates the sensitivity. Also, the deformed-RS parameters that set the H1-ttbar coupling and cross section are inherited from Ref. [10] but not stated here; a referee should ask for them.\n\nThat said, this is not a bad paper. The authors are honest about not doing detector simulation, and their conclusion is appropriately cautious about going above 1.2 TeV. The minor issues—section numbering, a footnote clarifying the ttbar+jets replacement—are trivial. If I were the editor, I would send it to peer review, but I would expect the referee to push on the systematics and the unstated model parameters. The paper's real value is as a first look at a possible channel; it should not be read as a final statement on HL-LHC reach.\n\nWho is this for? People working on warped extra dimension phenomenology or four-top searches at the LHC. I'd probably cite it as the first study of this particular channel, but I wouldn't rely on its luminosity numbers.\n\nRecommendation: accept for peer review with the expectation of revision.","headline":"A useful new four-top search channel for a deformed-RS KK Higgs, but the HL-LHC reach claim rests on a generator-level projection that a realistic background systematic could push past 3000/fb.","tokens_in":6996,"tokens_out":2261,"would_cite":true,"duration_ms":20858,"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 argues that the first Kaluza-Klein excitation of the Higgs boson in the deformed Randall-Sundrum model, produced in association with a top-antitop pair and decaying into a boosted top pair, can be probed up to a mass of about…","keywords":["Kaluza-Klein Higgs","Randall-Sundrum model","deformed metric","four-top final state","boosted top quarks","high-luminosity LHC","top-associated Higgs production","hadronic search channel"],"falsifier":"Count events in the four-top hadronic sample after the paper's cuts, in a reconstructed-mass window around 1.2 TeV, using 3000 fb$^{-1}$ of HL-LHC data: if the observed yield matches the Standard Model background prediction with no excess, the claimed $3\\sigma$ reach at 1.2 TeV is falsified. A cheaper test is a detector-level Monte-Carlo rerun of the same selection including realistic b-tagging and mistag efficiencies, to see whether the required luminosity stays below 3000 fb$^{-1}$.","tokens_in":5972,"feed_emoji":"⚛️","tokens_out":10702,"duration_ms":88150,"temperature":0.7,"pith_summary":"The paper sets out to show that the first Kaluza-Klein excitation of the Higgs boson in a deformed Randall-Sundrum warped-extra-dimension model is not out of reach for the high-luminosity LHC. The production channel is $pp \\to H_1 t\\bar t$, and the KK Higgs is assumed to decay predominantly into a boosted $t\\bar t$ pair, giving a distinctive four-top final state in which two tops are boosted. Using a hadronic, zero-lepton selection with high jet multiplicity, several b-tags, a large scalar $p_T$ sum, and a mass-window cut, the authors find that a $3\\sigma$ signal could be seen for $H_1$ masses up to about 1.2 TeV within the planned 3000 fb$^{-1}$ of integrated luminosity. If correct, this gives a concrete near-term experimental test of a specific extension of the Standard Model that addresses the hierarchy problem.","feed_headline":"KK Higgs up to 1.2 TeV within HL-LHC reach","feed_subtitle":"A 3σ signal needs 1443 fb^-1 at 1.2 TeV, below the 3000 fb^-1 target.","key_machinery":"The central object is $H_1$, the first Kaluza-Klein mode of the Higgs boson in the deformed Randall-Sundrum model, whose metric deformation keeps the KK Higgs in the 1 TeV range. The argument is carried by the special kinematics of the final state: $pp\\to H_1 t\\bar t \\to t\\bar t t\\bar t$, where the two tops from the $H_1$ decay are boosted. These tops decay hadronically and their products are clustered into anti-$k_T$ jets with $R=0.4$. The discriminating mechanism is a cut sequence — zero leptons, $N_{\\text{jets}}\\ge 9$, $N_{\\text{b-tags}}\\ge 3$, $H_T\\ge 1250$ GeV, and a window on the mass reconstructed from five jets — which suppresses the irreducible SM $t\\bar t t\\bar t$ and $t\\bar t b\\bar b$ backgrounds enough to make the small signal visible at high luminosity.","core_discovery":"The central quantitative claim is that with 3000 fb$^{-1}$ at 14 TeV, the deformed-RS KK Higgs can be probed at $3\\sigma$ up to $M_{H_1}\\simeq 1.2$ TeV in association with a top pair. The supporting numbers, for the all-hadronic boosted-top channel, are required luminosities of 377 (1046), 819 (2276), 1123 (3119), and 1443 (4008) fb$^{-1}$ for $3\\sigma$ ($5\\sigma$) at $M_{H_1}=900$, 1000, 1100, and 1200 GeV. The $5\\sigma$ discovery reach in this channel is limited to about 1 TeV, since 1000 GeV needs 2276 fb$^{-1}$ and 1100 GeV already needs 3119 fb$^{-1}$. Beyond 1.2 TeV, the production cross-section is too small for the LHC, and the authors conclude that such masses require a future higher-energy collider. The search channel is viable because the two tops from the heavy Higgs decay are boosted, allowing $H_1$ mass reconstruction from five jets while background is reduced by the jet-count, b-tag, and $H_T$ criteria.","pith_inferences":["Because the authors use parton-shower simulation without detector effects or systematic uncertainties, and note that b-mistagging would raise the luminosity needs, the quoted reach should be read as a favourable threshold; a full detector study could push the 1.2 TeV point beyond 3000 fb$^{-1}$.","The quantitative signal rate is inherited from a specific set of deformed-RS parameters chosen in the earlier study; if those parameters vary, both the $H_1 t\\bar t$ production cross-section and the $H_1\\to t\\bar t$ branching fraction change together, so the reach curve would shift as a whole.","The same selection is a generic boosted-top-pair resonance search and could be applied to other new particles decaying to $t\\bar t$, with the mass window moved to the candidate resonance mass.","A null result with 3000 fb$^{-1}$ in this channel would not simply mean no KK Higgs; it would start excluding the deformed-RS parameter region that gives a 1 TeV-scale $H_1$, a useful constraint when combined with the gluon-fusion channel studied earlier."],"forward_implications":["At the planned 3000 fb$^{-1}$ of the HL-LHC, a $3\\sigma$ excess would be expected for $H_1$ masses between 0.9 and 1.2 TeV in the all-hadronic four-top channel.","A $5\\sigma$ discovery in this channel would require 1046 fb$^{-1}$ at 900 GeV and 2276 fb$^{-1}$ at 1 TeV; above 1 TeV, more than 3000 fb$^{-1}$ is needed.","Masses above about 1.2 TeV are not accessible in this channel at the LHC because the associated-production cross-section falls too steeply, and the authors defer them to a future higher-energy collider.","The irreducible backgrounds $t\\bar t t\\bar t$ and $t\\bar t b\\bar b$ can be reduced below the signal by the jet-count and b-tag requirements, so the boosted-top hadronic final state is a workable route for this resonance."],"supporting_citations":[{"why":"Supplies the deformed-RS model implementation and couplings for the KK Higgs that set the signal cross-sections.","marker":"[10]"},{"why":"Provides the background choice and boosted-top search strategy that the cut flow closely follows.","marker":"[13]"},{"why":"Supplies the classification of four-top final states and the discriminating variables used in the search.","marker":"[12]"},{"why":"Gives the current ATLAS bound on four-top-like resonances that the search is compared with.","marker":"[14]"},{"why":"Generates the parton-level amplitudes for signal and background.","marker":"[15]"},{"why":"Performs the parton showering of the generated events.","marker":"[17]"},{"why":"Defines the anti-$k_T$ jet clustering algorithm used to form jets.","marker":"[19]"},{"why":"Supplies the FastJet implementation used for jet clustering.","marker":"[21]"}],"fun_headline_variants":["KK Higgs reach 1.2 TeV at HL-LHC via boosted tops","Boosted tops unlock KK Higgs at LHC up to 1.2 TeV","Four-top final state probes KK Higgs to 1.2 TeV","KK Higgs: 3σ up to 1.2 TeV, 5σ only to 1 TeV","HL-LHC can probe KK Higgs up to 1.2 TeV in ttH"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The result stands or falls on the assumption that the deformed-RS model parameters used for the signal are the right ones, and that cutting parton-shower events without a full detector simulation or systematic uncertainties gives a faithful estimate of how many signal and background events survive.","fun_headline_variants_meta":{"raw":{"variants":["KK Higgs reach 1.2 TeV at HL-LHC via boosted tops","Boosted tops unlock KK Higgs at LHC up to 1.2 TeV","Four-top final state probes KK Higgs to 1.2 TeV","KK Higgs: 3σ up to 1.2 TeV, 5σ only to 1 TeV","HL-LHC can probe KK Higgs up to 1.2 TeV in ttH"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.00074,"raw_usage":{"total_tokens":3328,"prompt_tokens":994,"completion_tokens":2334,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":610,"completion_tokens_details":{"reasoning_tokens":2219}},"tokens_in":610,"tokens_out":2334,"duration_ms":15157,"temperature":1.0,"reasoning_tokens":2219,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-14T10:05:12.032073+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Count events in the four-top hadronic sample after the paper's cuts, in a reconstructed-mass window around 1.2 TeV, using 3000 fb$^{-1}$ of HL-LHC data: if the observed yield matches the Standard Model background prediction with no excess, the claimed $3\\sigma$ reach at 1.2 TeV is falsified. A cheaper test is a detector-level Monte-Carlo rerun of the same selection including realistic b-tagging and mistag efficiencies, to see whether the required luminosity stays below 3000 fb$^{-1}$.","supporting_citations":[{"cited_title":"The bulk Higgs in the Deformed RS Model","cited_arxiv_id":"1712.04966","evidence_quote":"Supplies the deformed-RS model implementation and couplings for the KK Higgs that set the signal cross-sections."}],"review_version":1}