{"id":"c1ed7511-5177-4003-a908-daba25e489a5","arxiv_id":"2412.19317","paper_version":1,"verdict":"UNVERDICTED","confidence":"HIGH","novelty_score":1.0,"correctness_risk":"low","formal_verification":"none","parameter_count":1,"one_line_summary":"An ATLAS conference document summarizing two searches for R-parity-violating higgsinos in 139 fb^-1 of 13 TeV data, finding no excess and setting mass exclusions up to 440 GeV.","lead":"This paper is a conference summary of two ATLAS searches for supersymmetric higgsino particles that decay through R-parity violating couplings, using 139 inverse femtobarns of 13 TeV LHC proton-proton collisions. It reports no new physics signal and gives limits on the allowed higgsino masses, building on two already published ATLAS analyses.","discovery_kind":"review","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Concern: the exclusion claims rest on background estimates whose matrix-method closure is shown only after loosening signal-region requirements; an unvalidated fake-lepton efficiency extrapolation could shift the quoted LSP mass exclusions.","rationale":"The reader correctly identifies the fake/non-prompt lepton efficiency extrapolation (Section 4.3) as the weakest assumption, and I agree this is the most load-bearing technical point for the quoted exclusions. However, the reader's primary reason for UNVERDICTED is that the paper is an expository conference proceedings summarizing two already-published ATLAS analyses (Refs 4 and 5), with no new quantitative contribution. That is a fair characterization of the document's genre, but it is not itself a correctness concern about the physics claim. If the question is whether the central claim (no excess; exclusions up to 320 GeV for UDD RPV and 440 GeV for bRPV) is supported by the evidence presented, the argument is a chain of inherited results, validation plots, and cross-checks. The weakest link in that chain is the matrix-method assumption, exactly as the reader states. I do not find a fatal flaw: the paper is candid about the assumption and its uncertainties, provides an MC-Template cross-check, and shows good agreement in validation regions. The concern is that the closure tests are performed with one signal-region requirement removed (Figures 5-8), so the exact signal-region phase space is not directly validated, and the fake-efficiency extrapolation from ttbar-enriched control regions to signal regions with zero b-jets and high mT2 is where a miscalibration would most directly change the exclusion boundaries. This warrants a conditional verdict: the physics summary is acceptable as a proceedings paper, but the exclusions should be read as carrying the matrix-method extrapolation uncertainty, and a dedicated check (or citation to the relevant closure test in Ref 4) would settle the residual concern. If the published analyses include such a closure test, the concern is fully answered; if not, the exclusion claim should be presented with that caveat made explicit.","tokens_in":17152,"tokens_out":2146,"duration_ms":17886,"concrete_test":"Recompute the UDD RPV exclusion limit (Figure/claim for LSP masses 200-320 GeV) after repeating the matrix-method estimate with the fake/non-prompt efficiency measured in a dedicated control region with no mT2 upper cut and with zero b-jets (matching SRbRPV_2l), and compare the resulting background yield in SRbRPV_2l with the nominal estimate. Alternatively, in the published ATLAS analysis (Ref 4), inspect the binned fake-lepton efficiency as a function of mT2 in the six control regions; if the efficiency changes by more than the assigned systematic uncertainty when extrapolated to mT2 > 60 GeV and zero b-jets, the 200-320 GeV exclusion band could shift.","verdict_should_be":"CONDITIONAL","load_bearing_attack":"The paper's central physics claim (Section 6) is that LSP masses between 200 GeV and 320 GeV are excluded for the UDD RPV model and that bRPV higgsino masses are excluded up to 440 GeV. These exclusions inherit from Refs 4 and 5, but the document itself presents the supporting background estimates, and the load-bearing condition is that the data-driven fake/non-prompt lepton estimate remains valid in the signal regions. Section 4.3 states the matrix method assumption that fake-lepton efficiencies are the same in control and signal regions and independent of the selection requirements. The validation plots (Figures 5-8) do not fully close this gap: they show closure after applying all signal-region requirements except one discriminating variable (e.g. mT2 or the b-jet pT fraction), so the tested phase space is close to but not identical to the final signal regions. More importantly, the fake efficiency is measured in ttbar-enriched control regions with upper cuts on EmissT and meff, then extrapolated to signal regions with much harder EmissT, meff and mT2 requirements and, in the bRPV 2-lepton region, exactly zero b-jets. The systematic uncertainties in Table 4 address pT-dependent and topology-dependent variations, but they are sizable (up to 30-80%) and were derived from alternative ttbar-like phase spaces. The MC-Template cross-check provides partially independent support, including good agreement in Figures 5-8, and the document candidly notes regions where the two methods hint at differences (Section 4.4, Figures 7-8). However, because the quoted exclusions are sensitive to the fake background normalization in the high-mass tails, and the closure tests are one-removed from the exact signal region definitions, the extrapolation assumption is not fully tested by the evidence presented in this document. This does not invalidate the claims, but it is the point where the argument is least secure.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This document summarizes two ATLAS searches for direct higgsino pair production with R-parity-violating (RPV) couplings, using 139 fb^-1 of 13 TeV proton-proton collision data. The first model is the bRPV scenario with lepton-number-violating bilinear terms; the second is the UDD RPV scenario with a non-zero lambda''_323 coupling. The paper describes the signal region definitions (Tables 1 and 2), the background estimation strategies for WZ+jets, electron charge flip, and fake/non-prompt leptons (including the matrix method and the MC-Template cross-check), the validation regions and figures, the systematic uncertainties, and the results: no significant excess in the discovery signal regions, model-independent upper limits in Table 5, UDD RPV LSP masses between 200 GeV and 320 GeV excluded, and bRPV higgsino masses excluded up to 440 GeV. The document is based on a presentation at ICNFP 2022 and reuses figures and quantitative results from the ATLAS publications in Refs. 4 and 5.","tokens_in":17449,"tokens_out":7188,"duration_ms":69052,"significance":"If the quoted results are correct, the paper summarizes useful new exclusion information for RPV higgsino simplified models and provides model-independent limits that can be reinterpreted for other BSM scenarios. The manuscript's strengths are its clear presentation of the signal region selections, its explicit discussion of the assumptions and shortcomings of the fake/non-prompt lepton estimation, and its transparency about the validation gaps. The document is, however, a proceedings-style summary rather than an original measurement: the quantitative results are inherited from already-published ATLAS analyses, and the manuscript does not contain enough information to independently reproduce the background estimates or the limit-setting procedure. Its main value is as an accessible and candid overview of the two searches, not as a new physics result.","major_comments":[{"comment":"The central claims that 'there is no significant excess in any of the selected discovery signal regions' and that LSP masses between 200 GeV and 320 GeV are excluded for UDD RPV, with bRPV higgsino masses excluded up to 440 GeV, are presented as results, but the statistical inputs needed to verify them are not included in this manuscript. There is no table of observed and expected event yields per signal region with the full uncertainty breakdown, no covariance information for the nuisance parameters, and no description of the likelihood used to set the limits. As written, the reader cannot tell whether these exclusions are asserted as the outcome of the analysis described here or quoted from Refs. 4 and 5. Please either add a complete yield table for all discovery and exclusion signal regions, or explicitly state in Section 6 that the exclusion limits are inherited from Refs. 4 and 5 and are not re-derived in this document.","section":"Section 6, Table 5"},{"comment":"The matrix-method assumption that 'the lepton fake/non-prompt efficiencies are the same in the control and signal regions, and independent of the selection requirements' is load-bearing for the fake-lepton background estimate. The efficiency is measured in ttbar-enriched control regions with upper cuts on E_T^miss and m_eff, while the signal regions require much harder E_T^miss, m_eff, and m_T2 cuts, and the bRPV 2-lepton signal region requires exactly zero b-jets. The validation plots in Figures 5-8 show closure after applying all signal-region requirements except one discriminating variable, so the tested phase space is close to, but not identical to, the final signal regions. The systematic uncertainties in Table 4 (up to +30%/-80% for muons) are derived from alternative ttbar-like phase spaces and do not directly test the extrapolation into the zero-b-jet, high-m_T2 regime. The text candidly acknowledges this limitation, but it does not quantify how a closure-test residual would shift the quoted exclusion limits. Please add a quantitative statement of the limit shift under a conservative variation of the fake efficiency, or state clearly that the exclusions rely on the validation published in Refs. 4 and 5 rather than on the material in this document.","section":"Section 4.3, Section 4.4, Table 4, Figures 5-8"},{"comment":"The manuscript explicitly limits the background discussion to the discovery signal regions in Tables 1 and 2, stating that 'only the background strategy used to get the results in the signal regions shown in Tables 1 and 2 is discussed.' However, the UDD RPV exclusion claim of LSP masses between 200 GeV and 320 GeV is driven by the one-lepton neural-network signal regions and by the two-same-charge-lepton regions with the m_ellj < 155 GeV requirement, which are only described in Ref. 5. The background estimation for those regions is not presented here, so the paper quotes an exclusion result without describing the methods that produce it. Please add at least a summary of the one-lepton background estimation, or clearly state that the UDD exclusion is taken from Ref. 5 and is not derived from the material in this document.","section":"Section 4 (first paragraph) and Section 6"}],"minor_comments":[{"comment":"The text says 'two RPV UUD production modes' but the model is UDD; this typo appears both in Section 6 and in the Figure 11 caption.","section":"Section 6 and Figure 11 caption"},{"comment":"The statement that 'in some regions, the MC-Template estimations have lower uncertainties and this will be studied in more detail in future' and the claim that the excess in SR_RPV_2l3b 'would be even lower' with the MC-Template method are not quantified; please specify which regions and by how much.","section":"Section 4.4 and Section 6"},{"comment":"The optimization procedure uses a flat 30% systematic uncertainty on the background prediction, but no motivation or reference is given for this value; a brief justification or a reference to the original optimization study would be helpful.","section":"Section 2"},{"comment":"The bilinear RPV model is described as having tan beta set to 5 to suppress higgsino decays to tau leptons, but beta is not defined in the text; a one-line definition or reference would improve readability.","section":"Section 1"},{"comment":"The sentence 'The conclusion is that, for discovery, more inclusive (general) signal regions should still be used' is presented as a general lesson without quantitative support; if it is an opinion, it should be labeled as such.","section":"Section 6"}],"recommendation":"major_revision","confidential_remarks":"This is a conference-proceedings-style summary of two already-published ATLAS analyses. Its contribution is mainly pedagogical and organizational rather than a new physics result. If the journal does not publish such derivative summaries, the paper may be outside the journal's scope. The self-citation to Refs. 4 and 5 is appropriate given the provenance, but the manuscript should state much more prominently that the exclusion limits are not independently re-derived here and that the background methods are summarized rather than fully documented."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Colleague, this is a conference-proceedings write-up, not a new analysis. It summarizes two ATLAS searches for RPV higgsinos using 139 fb^-1, with all central numbers taken from Refs 4 and 5. The reader's scoring matches mine: novelty is thin, soundness is inherited. What the document does add is a candid review of the background-estimation methods, especially the matrix method for fake/non-prompt leptons and the MC-template cross-check. The author openly discusses where the matrix method assumption of constant fake efficiencies is fragile, where the two methods hint at differences, and where future work should combine them. That is a real service, and it is done without overclaiming.\n\nThe soft spots are proportional to the format. There is no new measurement, so the physics impact is zero beyond the original papers. The stress-test worry about the fake-efficiency extrapolation is legitimate, but it is a critique of the ATLAS analysis itself, and the document actually flags much of it. The closure tests in Figures 5-8 are one-removed from the final signal regions, and the efficiencies carry 30-80% systematics in some bins, but the quoted limits already include those uncertainties and were peer-reviewed. So I do not see a load-bearing flaw in this document's argument, because it does not make a new argument. The self-citation pattern is appropriate: the results are ATLAS results.\n\nWho is this for? A reader who wants a compact map of these two searches, the SR definitions, and the background-estimation pitfalls without going through the full JHEP/EPJC papers. That is a legitimate but niche value. I would not cite it in my own work; I'd cite the original searches. I would not send it to a serious referee for a research journal; it is a proceedings summary. If a conference proceedings editor wants a light review for accuracy, that is fine, but it does not need the full referee treatment.\n\nSerious thinker: yes — the author knows the material and is honest about the limitations.","headline":"A clear, honest conference summary of two published ATLAS RPV higgsino searches; no new results, but a useful review of the fake-lepton background methods and their limitations.","tokens_in":18019,"tokens_out":2334,"would_cite":false,"duration_ms":20695,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":false},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["11.30.Pb","12.60.Jv"],"model":"deepseek-v4-flash","headline":"No significant excess in ATLAS searches for R-parity violating higgsinos, new exclusion limits set.","keywords":["R-parity violation","higgsino","supersymmetry","same-charge leptons","multileptons","LHC","ATLAS","exclusion limits"],"falsifier":"Measure the fake/non-prompt lepton efficiency in a control region that is kinematically very close to the signal regions (for example, with mT2 above 60 GeV and four or more jets) using the same tag-and-probe technique, and compare it with the weighted combination of efficiencies measured in the standard top-antitop enriched control regions; if the two efficiencies differ by more than the quoted systematic uncertainties, the matrix-method background prediction used to derive the limits would be miscalibrated and the exclusion boundaries would shift.","tokens_in":1896,"feed_emoji":"⚛️","tokens_out":3026,"duration_ms":56125,"temperature":0.7,"pith_summary":"This paper reports two searches for supersymmetric higgsinos that decay through R-parity violating couplings into final states with leptons and (b-)jets, using 139 fb$^{-1}$ of 13 TeV proton-proton collisions recorded by the ATLAS detector. The central claim is that no significant excess of events over the Standard Model background is observed in any of the selected signal regions, and this null result translates into concrete exclusion limits: for the UDD model the lightest supersymmetric particle (LSP) mass is excluded between 200 and 320 GeV, while for the bRPV model higgsino masses are excluded up to 440 GeV. A sympathetic reader cares because these are among the few supersymmetric scenarios that could solve the hierarchy problem while remaining consistent with LHC data, and the paper demonstrates that the challenging same-charge and tri-lepton final states can be handled with data-driven background estimates.","feed_headline":"ATLAS sees no RPV higgsino signal, sets new limits","feed_subtitle":"Two LHC searches with leptons and jets rule out LSP masses up to 320 GeV and higgsinos up to 440 GeV.","key_machinery":"The argument is carried by dedicated signal regions defined through kinematic discriminants: the stransverse mass $m_{T2}$, missing transverse energy $E_{\\mathrm{T}}^{\\mathrm{miss}}$, effective mass $m_{\\mathrm{eff}}$, b-jet and jet multiplicities, and angular separations. These are combined with two complementary data-driven background estimators: the matrix method, which uses loose-versus-tight lepton efficiencies to count fake/non-prompt leptons, and the MC-Template method, which rescales simulated background templates with correction factors from control regions. Electron charge-flip backgrounds are suppressed with a boosted decision tree and estimated by weighting opposite-charge data with a charge-flip probability. All final estimates are produced with profile-likelihood fits implemented in the HistFitter framework, which supplies the background-only, model-dependent, and model-independent limits.","core_discovery":"The paper establishes, on the basis of the full Run 2 dataset, that the direct pair production of higgsinos with bilinear R-parity violation (bRPV) or with a non-zero baryon-number violating coupling $\\lambda''_{323}$ does not produce a statistically significant excess in any of the optimized discovery signal regions. The observed yields are compatible with the Standard Model prediction, leading to 95% confidence level upper limits on the visible cross section (for example, $\\langle\\epsilon\\sigma\\rangle^{95}_{\\mathrm{obs}}$ between 0.04 and 0.15 fb in the UDD RPV discovery regions) and to model-dependent exclusions: for the UDD RPV model, higgsino LSP masses from 200 to 320 GeV are excluded, while for the bRPV model higgsino masses up to 440 GeV are excluded. The paper also validates the two background-estimation methods, the matrix method and the MC-Template method, by showing good agreement between data and prediction in control and validation regions.","pith_inferences":["A direct extension is to combine the matrix and MC-Template background estimates in a single simultaneous fit; the paper notes this as a future improvement, and doing so would likely reduce the total uncertainty in the two-same-charge plus two- or three-b-jet regions where the MC-Template method currently shows lower uncertainties.","The small (about 1 sigma) excess seen in the SR-RPV-2l3b region, which becomes even smaller when the MC-Template method is used, suggests that additional data from Run 3 could either confirm a genuine signal or solidify the null result; monitoring this region is a concrete testable next step.","The assumptions behind the matrix method could be weakened by measuring fake/non-prompt efficiencies separately for each source (for example, conversions versus hadronic decays) and as a function of additional variables beyond $p_{\\mathrm{T}}$ and $\\eta$, which the paper identifies as a potential future improvement.","Because the paper considers only prompt higgsino decays, a natural extension is to apply the same signal regions and background strategies to RPV scenarios with displaced vertices, where the lepton identification and background composition would differ significantly."],"forward_implications":["If no signal is present, the exclusion limits narrow the allowed parameter space for R-parity violating higgsino simplified models, making it harder for these scenarios to address the hierarchy problem without new physics beyond these mass ranges.","The model-independent upper limits on visible cross sections can be reinterpreted by theorists to constrain any new-physics model producing events with two same-charge or three leptons in the same kinematic regions.","The validation of the matrix method against the MC-Template method demonstrates that data-driven fake-lepton estimation is reliable in high-multiplicity, high-$m_{T2}$ signal regions, supporting its use in future searches for other exotic signatures.","The inclusion of neural-network discriminants in the UDD exclusion regions illustrates how machine-learning classifiers can substantially improve sensitivity in final states with many jets, a lesson applicable to broader SUSY and beyond-the-Standard-Model searches."],"supporting_citations":[{"why":"ATLAS Collaboration, JHEP 11 (2023) 150 — the primary analysis paper that defines the bRPV and UDD discovery signal regions, supplies the signal region yields and the model-independent limits in Table 5.","marker":"[4]"},{"why":"ATLAS Collaboration, Eur. Phys. J. C 81 (2021) 1023 — the primary analysis for the UDD exclusion signal regions, including the neural-network discriminant in one-lepton regions that drives the 200-320 GeV LSP exclusion.","marker":"[5]"},{"why":"ATLAS Collaboration, Tools for estimating fake/non-prompt lepton backgrounds — provides the matrix method that is the central data-driven estimator for the dominant detector background in the same-charge and tri-lepton channels.","marker":"[22]"},{"why":"HistFitter framework — supplies the profile-likelihood fitting machinery used for all background-only, model-dependent, and model-independent statistical interpretations.","marker":"[14]"},{"why":"ATLAS electron and photon performance paper — supplies the likelihood-based electron charge-flip probability measurement used to estimate the charge-flip background in same-charge final states.","marker":"[20]"}],"fun_headline_variants":["ATLAS Run 2 finds no RPV higgsino signal, tightens limits","ATLAS excludes higgsino masses up to 440 GeV in RPV search","No excess from RPV higgsinos; ATLAS sets new limits","ATLAS Run 2 data exclude RPV higgsinos, set new limits","ATLAS excludes higgsinos in two RPV scenarios"],"cache_read_input_tokens":20096,"weakest_assumption_plain":"The background prediction for the dominant fake/non-prompt lepton source relies on the assumption that the efficiency for such leptons to pass the tight selection is the same in the control regions where it is measured as in the signal regions, independent of jet multiplicity, mT2, or other signal-region requirements.","fun_headline_variants_meta":{"raw":{"variants":["ATLAS Run 2 finds no RPV higgsino signal, tightens limits","ATLAS excludes higgsino masses up to 440 GeV in RPV search","No excess from RPV higgsinos; ATLAS sets new limits","ATLAS Run 2 data exclude RPV higgsinos, set new limits","ATLAS excludes higgsinos in two RPV scenarios"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000677,"raw_usage":{"total_tokens":3043,"prompt_tokens":875,"completion_tokens":2168,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":491,"completion_tokens_details":{"reasoning_tokens":2078}},"tokens_in":491,"tokens_out":2168,"duration_ms":16008,"temperature":1.0,"reasoning_tokens":2078,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-11T00:41:44.966169+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure the fake/non-prompt lepton efficiency in a control region that is kinematically very close to the signal regions (for example, with mT2 above 60 GeV and four or more jets) using the same tag-and-probe technique, and compare it with the weighted combination of efficiencies measured in the standard top-antitop enriched control regions; if the two efficiencies differ by more than the quoted systematic uncertainties, the matrix-method background prediction used to derive the limits would be miscalibrated and the exclusion boundaries would shift.","supporting_citations":[{"cited_title":"Search for direct production of winos and higgsinos in events with two same-charge leptons or three leptons in $pp$ collision data at $\\sqrt{s}=13$ TeV with the ATLAS detector","cited_arxiv_id":"2305.09322","evidence_quote":"ATLAS Collaboration, JHEP 11 (2023) 150 — the primary analysis paper that defines the bRPV and UDD discovery signal regions, supplies the signal region yields and the model-independent limits in Table 5."}],"review_version":1}