{"id":"597dae25-28a0-483a-84f4-d6ba3cd8725c","arxiv_id":"1909.02325","paper_version":3,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":2,"one_line_summary":"A simulation predicts that the mono-b signature from electroweak single-stop production can probe stop masses up to roughly 1.6 TeV at the 27 TeV High Energy LHC, assuming systematic uncertainties stay at the few-percent level.","lead":"This paper simulates a rare way to produce the top squark, the supersymmetric partner of the top quark, at future proton colliders. It finds that a single stop plus a bottom quark and missing energy could be detected at the planned High Energy LHC, offering a second way to confirm supersymmetry if stop pairs are seen first.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The 5σ reach claim depends on unquantified 'few percent' systematics; even a 5% background normalization uncertainty could reduce the significance below discovery level.","rationale":"The paper is a standard, clearly presented sensitivity study for a plausible signature. The methodology is appropriate, and the authors are transparent about the main limitation in Sec. III, explicitly stating that systematics must be controlled at a few-percent level. My stress-test identifies this unquantified systematic assumption as the most load-bearing condition on the central reach claim. The reader's weakest_assumption focused on chargino invisibility; I find that assumption reasonable in the simplified-model context and for the parameter region of the claimed reach, so my primary concern differs. The background list is incomplete but likely secondary given the analysis cuts. A quantitative treatment of systematic uncertainties would turn the projection into a more robust claim; without it, the headline numbers are conditional. This supports the reader's CONDITIONAL verdict, so no change in verdict is needed. I credit the authors for including the caveat in the text, but the abstract omits it, which should be addressed in a revision.","tokens_in":9932,"tokens_out":11953,"duration_ms":129976,"concrete_test":"Obtain the signal and background yields after the final selection from the authors, or reproduce the analysis with the same MadGraph/Pythia/Delphes setup and cuts. Then compute the profile-likelihood significance including a background-normalization nuisance parameter (log-normal or Gaussian) with f = 0.01, 0.03, 0.05, and 0.10, and map the 5σ contour in the (m_t~1, μ) plane for each level. If the stop mass reach at 5σ drops by more than 20% when f increases from 0 to 0.05, the headline claim must be restated as a function of the systematic level, and the abstract should carry that caveat.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The headline reach (stop mass up to 1.6 TeV and higgsino mass up to 550 GeV at 5σ) is computed using a purely statistical significance S/√B. In Sec. III and the conclusion, the authors acknowledge that systematics will degrade the significance and state that they must be controlled 'at a few percent level,' but they never quantify the degradation. Because S/B is small (the text says so), a few-percent background normalization uncertainty can dominate the error budget. For a contour point with S = 5√B and a background uncertainty f·B, the significance becomes roughly S/√(B + (fB)²). For f = 0.05 and B ≈ 10³, this reduces a 5σ signal to about 2.7σ; even f = 0.02 reduces it to about 4σ. The actual required precision is therefore closer to 1–2%, not the vague 'few percent.' The paper does not quote S and B in the signal region, so the robustness of the 1.6 TeV reach cannot be checked from the paper alone. The abstract presents the reach without this conditional caveat, which overstates the result. The chargino invisibility assumption, highlighted by the reader, is a defining feature of the simplified model and is well justified for the claimed parameter range (μ ≲ 550 GeV with M1 = M2 = 1 TeV); it is not the most load-bearing concern. The incomplete background list (missing W+jets, diboson, single top) is a secondary issue, as the high ETmiss and leading b-jet pT cuts likely suppress those contributions, but it still warrants mention. The central numeric claim rests on an unquantified, potentially unattainable systematic precision.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper studies the mono-b-jet signature from electroweak single-stop production, pp -> t~1 chi~1- -> b + ETmiss, in a simplified MSSM with only a right-handed stop and higgsinos. The authors compute leading-order cross sections with MadGraph5_aMC@NLO, apply an NLO K-factor of 1.4, and simulate the signal against the dominant SM backgrounds (Z+jets and ttbar) using Pythia and Delphes within CheckMATE2. After a set of cuts requiring a leading b-jet with pT above 500 (550) GeV at the 14 (27) TeV collider, ETmiss above 450 (500) GeV, HT3 below 100 (150) GeV, and a minimum azimuthal separation between jets and the missing momentum, the statistical significance S/sqrt(B) is evaluated. The main results are that the HL-LHC can exclude stop masses up to about 1.25 TeV at 2 sigma, and the HE-LHC can probe stop masses up to about 1.6 TeV and higgsino masses up to 550 GeV at 5 sigma with 15 ab^-1, provided systematic uncertainties are controlled at the few-percent level. The paper also discusses the role of this channel in confirming a stop discovered in pair production.","tokens_in":10261,"tokens_out":6570,"duration_ms":66531,"significance":"If the quoted reach is robust, the paper demonstrates a useful complementary probe of natural SUSY that is qualitatively distinct from conventional stop pair searches. The analysis is self-contained, uses standard tools, and does not rely on fitting any output; the simplified model is motivated by natural SUSY and the mass ranges considered are consistent with current constraints. The main limitation is that the quantitative reach contours depend on an unquantified 'few-percent' systematic budget and on a background simulation that omits several potentially relevant SM processes. These issues do not invalidate the qualitative conclusion that the mono-b channel is interesting, but they do mean that the headline 5 sigma numbers should be regarded as optimistic upper bounds rather than robust projections.","major_comments":[{"comment":"The significance is computed purely as S/sqrt(B), and the text acknowledges only qualitatively that systematics will degrade it ('a few percent level'). Because S/B is small for the 5 sigma contour, a 5% background normalization uncertainty reduces the significance to roughly S/sqrt(B + (0.05B)^2), which for B of order 10^3 turns a nominal 5 sigma into approximately 2.7 sigma; even a 2% uncertainty gives about 4 sigma. The paper does not report S and B in the signal region, so the actual robustness of the 1.6 TeV stop-mass claim cannot be checked. Please provide the event yields and a significance calculation that includes a systematic uncertainty model (or, at minimum, an explicit budget showing what level of precision is required). The abstract and the conclusion should then state the reach as conditional on that budget.","section":"Sec. III, Fig. 5"},{"comment":"The simulation includes only Z+jets and ttbar. The text claims these are the largest and subdominant backgrounds, but gives no quantitative argument that W+jets, single top, diboson, and QCD multijet production are negligible after the tight pT(b1), ETmiss, and Delta phi cuts. Since the discovery significance is based on small S/B, an additional background at half the ttbar level would shift the contours in Fig. 5 noticeably. Please either add these backgrounds to the simulation or provide a generator-level estimate (e.g., with cross-section reweighting) showing they are negligible.","section":"Sec. III (event selection)"},{"comment":"No cutflow or final event counts are provided anywhere in the paper; Fig. 5 is not reproducible from the text. For the benchmark point (m_t~1 = 1000 GeV, mu = 200 GeV) and for the 5 sigma contour points, please provide a cutflow table with signal, Z+jets, and ttbar yields after each selection step, as well as the total expected background and S/B. This is necessary both for the reader to assess the reach and to quantify the systematics sensitivity raised above.","section":"Sec. III (no cutflow)"},{"comment":"The signal signature relies on treating the chargino chi~1+/- as invisible because its mass splitting with the LSP neutralino is 'small.' The paper never specifies the mass splitting for the parameter points shown in Fig. 5 (e.g., tan beta, M1, M2), nor does it check that the chargino decay products are in fact too soft to pass the lepton veto and jet selection. Please report the chargino-neutralino mass splitting across the displayed mu range and demonstrate that the decay products are negligible, or restrict the reach to parameters where this holds.","section":"Sec. III, before Eq. (16)"}],"minor_comments":[{"comment":"The abstract states the 5 sigma reach without the systematic caveat, whereas the conclusion says 'If the systematic uncertainty can be reduced to a few percent level.' Please align the abstract with the conditional wording in the conclusion.","section":"Abstract and Conclusion"},{"comment":"The sentence 'The NLO QCD corrected cross sections of the process pp -> t~1 t~*1 with the Prospino [60]' is missing a verb; it should read 'are obtained with Prospino.'","section":"Sec. II (cross sections)"},{"comment":"The scale choice mu_R = mu_F = m_Z for a TeV-scale process is not standard; please justify it or document the scale dependence.","section":"Sec. II"},{"comment":"The cut values used in the analysis are not indicated on the distribution plots; adding vertical lines for pT(b1), ETmiss, and HT3 would help the reader assess the signal-background separation.","section":"Sec. III, Figs. 3 and 4"}],"recommendation":"major_revision","confidential_remarks":"This manuscript presents a straightforward and reasonably executed phenomenological study. My major concern is that the central reach claim is presented in the abstract as if it were unconditional, while the analysis uses only statistical uncertainties and an incomplete background list. With the requested cutflows, systematics treatment, and background justification, the paper can be made reliable. No concerns about circularity or citation practice; the self-citations are contextual."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"What you should know: this is a competent, plain-vanilla phenomenological reach study for single stop production with a mono-b signature at the HL-LHC and HE-LHC. It produces new numerical projections—stop masses up to ~1.6 TeV and higgsino masses up to ~550 GeV at 5σ at the HE-LHC—for a channel that had only been discussed qualitatively. That is the extent of the novelty, but it is a legitimate extension, not a recycled calculation.\n\nWhat it does well: the simplified MSSM setup is clearly motivated by naturalness; the cross-section calculation uses MadGraph with an NLO K-factor, and the detector simulation is standard Delphes/CheckMATE. The distributions and cut choices are sensible, and the authors correctly note the single-stop rate overtakes pair production at very high masses. The chargino-as-invisible assumption is well justified for the higgsino-like regime considered, where the mass splitting is small.\n\nThe soft spots are the usual ones for this genre, but they matter more here because S/B is small. The significance is purely S/√B; the paper never quotes S and B, and the systematic caveat is a vague 'few percent level.' The stress-test arithmetic is right: at large B, a 5% background normalization uncertainty drops a nominal 5σ to about 2.7σ, and even 2% brings it to ~4σ. So the abstract's 5σ reach claim is overstated without that caveat. The background list also omits W+jets, single top, and diboson; the high cuts likely suppress them, but that should be checked. These are not fatal flaws—the central conclusion that the channel is complementary and worth pursuing holds—but the projections should be treated as statistical-only upper bounds.\n\nWho this is for: SUSY phenomenologists planning HL/HE-LHC searches and people thinking about how to confirm a stop discovery. It deserves a serious referee, though a revision should quantify systematics (or at least present S and B and a systematics-inclusive significance scan) and add the missing backgrounds. I'd send it to PRD rather than desk reject.","headline":"A solid, standard phenomenological reach study for a complementary stop search channel; the reach numbers are real but the headline 5σ claim depends on systematics the paper never quantifies.","tokens_in":10780,"tokens_out":2528,"would_cite":false,"duration_ms":27009,"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":"Single-stop electroweak production could reveal supersymmetric stops up to 1.6 TeV at a 27 TeV LHC.","keywords":["supersymmetry","stop squark","single stop electroweak production","mono-b events","naturalness","higgsino","HL-LHC","HE-LHC"],"falsifier":"If an independent measurement established that the chargino and the lightest neutralino are split by more than a few GeV, the chargino would decay to visible jets or leptons, and the mono-b final state assumed here would not be the signature; that single observation would falsify the reach estimate.","tokens_in":9707,"feed_emoji":"⚛️","tokens_out":10575,"duration_ms":99473,"temperature":0.7,"pith_summary":"The paper argues that a distinctive 'mono-b' signature—one b-jet plus large missing transverse momentum—from electroweak single-top-squark production can serve as a discovery and identification channel for supersymmetry at future LHC runs. In a simplified MSSM with only higgsinos and a right-handed stop, the process $pp \\to \\tilde t_1 \\tilde\\chi^-_1 \\to b + \\not E_T$ is shown to be observable. At the HE-LHC (27 TeV, 15 ab$^{-1}$) the authors find a $5\\sigma$ reach up to a stop mass of about 1.6 TeV and a higgsino mass of about 550 GeV, provided systematic uncertainties are controlled at the few-percent level. This matters because conventional stop-pair searches rely on $t\\bar t$ plus missing energy, a signature shared by other new-physics models; the mono-b channel would help confirm that a discovered signal is really a stop.","feed_headline":"Mono-b channel can spot stops up to 1.6 TeV at a 27 TeV LHC","feed_subtitle":"One b-jet plus large missing momentum would single out stops from models that mimic pair production.","key_machinery":"The mechanism is the electroweak production of a single stop in association with a chargino, $g b \\to \\tilde t_1 \\tilde\\chi^-_1$, which proceeds through $s$-channel bottom-quark exchange and $t$-channel stop exchange. The effective coupling entering the amplitudes is controlled by $\\tan\\theta_{\\mathrm{eff}}$, which mixes the bottom-Yukawa and electroweakino-stop couplings. In the simplified MSSM used here only the right-handed stop and higgsino-like electroweakinos are light; the lighter chargino $\\tilde\\chi^\\pm_1$ is assumed nearly degenerate with the neutralino LSP, so its decay products are undetectably soft and it counts as missing transverse energy. Event selection requires one boosted b-jet, large $\\not E_T$, small $H_{T3}$, and a minimum azimuthal separation between jets and missing momentum; the signal-to-background discrimination then drives the quoted mass reach.","core_discovery":"The central claim is that the single-stop electroweak production process $pp \\to \\tilde t_1 \\tilde\\chi^-_1$, followed by $\\tilde t_1 \\to b \\tilde\\chi^+_1$ and invisible chargino decay, yields a clean mono-b signature whose rate and kinematics allow the underlying stop and higgsino masses to be probed at future hadron colliders. Concretely, with the simplified natural-SUSY spectrum (right-handed stop, higgsino-like electroweakinos), the analysis reports $2\\sigma$ exclusion of stop masses up to about 1.25 TeV at the HL-LHC and 1.9 TeV at the HE-LHC, and a $5\\sigma$ discovery reach of about 1.6 TeV for the stop and 550 GeV for the higgsino mass parameter $\\mu$ at the HE-LHC with 15 ab$^{-1}$. The authors emphasize that the single-stop rate falls more slowly with mass than stop-pair production, so for heavy stops (beyond roughly 2.2 TeV at 14 TeV and 3.3 TeV at 27 TeV) the electroweak channel can outproduce the pair channel.","pith_inferences":["If the chargino-neutralino mass splitting is not small, the chargino would decay to visible leptons or jets; a combined mono-b plus soft-lepton search could extend coverage to larger splittings, a direction the paper does not quantify.","The few-percent systematic assumption could be tested with Z+jets control regions at the HL-LHC; if mistag rates are underestimated, the quoted reach would degrade.","The mono-b and mono-t channels probe the same production process through different stop decays; combining them should improve the overall sensitivity to natural SUSY beyond either channel alone."],"forward_implications":["At the HE-LHC, a $5\\sigma$ discovery of a 1.6 TeV stop and a 550 GeV higgsino is claimed in the mono-b channel, provided systematics stay at the few-percent level.","Without an excess, the mono-b search would exclude stops up to about 1.25 TeV at the HL-LHC and 1.9 TeV at the HE-LHC at $2\\sigma$.","For stops heavier than about 2.2 TeV (14 TeV) or 3.3 TeV (27 TeV), single-stop production has a larger cross section than stop-pair production, so the mono-b channel becomes the more sensitive probe of very heavy stops.","Observation of mono-b events together with the conventional $t\\bar t + \\not E_T$ signal would discriminate a stop from top-partner models such as T-odd top partners, which produce the same pair-production signature but not the same single-stop rate.","A future precision measurement of the single-stop cross section could distinguish higgsino-like from wino-like chargino scenarios, and right-handed from left-handed stops."],"supporting_citations":[{"why":"It presents the earlier mono-t single-stop analysis at the HL-LHC that motivates this mono-b study in the same simplified natural-SUSY framework.","marker":"[33]"},{"why":"It computes single-stop production in different SUSY models, supporting the claim that the electroweak channel distinguishes higgsino-like from wino-like charginos.","marker":"[34]"},{"why":"It supplies the Monte Carlo event generator used to produce parton-level signal and background events.","marker":"[56]"},{"why":"It provides the NLO QCD correction used as the K-factor of 1.4 for the single-stop cross section.","marker":"[57]"},{"why":"It supplies the NLO stop-pair cross section used as the comparison baseline for pair production.","marker":"[60]"},{"why":"It computes sparticle masses, couplings, and branching ratios for the benchmark spectra.","marker":"[62]"},{"why":"It provides the parton showering used in the event simulation.","marker":"[63]"},{"why":"It provides the detector simulation used to apply analysis cuts and estimate efficiencies.","marker":"[64]"},{"why":"It supplies the analysis framework used to implement event selection and derive the statistical significance.","marker":"[65]"}],"fun_headline_variants":["Mono-b events probe stops up to 1.6 TeV at 27 TeV LHC","Single stop electroweak search sees 1.6 TeV at HE-LHC","Mono-b channel reaches 1.6 TeV stops at 27 TeV LHC","Electroweak stop channel probes up to 1.9 TeV at HE-LHC","Mono-b signature: stop masses up to 1.6 TeV at HE-LHC"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The analysis assumes the chargino $\\tilde\\chi^\\pm_1$ and the lightest neutralino are nearly degenerate, so the chargino's decay products are too soft to register and it behaves as missing transverse energy; if that mass splitting is sizeable, the mono-b signature would acquire extra jets or leptons and the quoted reaches would not hold.","fun_headline_variants_meta":{"raw":{"variants":["Mono-b events probe stops up to 1.6 TeV at 27 TeV LHC","Single stop electroweak search sees 1.6 TeV at HE-LHC","Mono-b channel reaches 1.6 TeV stops at 27 TeV LHC","Electroweak stop channel probes up to 1.9 TeV at HE-LHC","Mono-b signature: stop masses up to 1.6 TeV at HE-LHC"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000667,"raw_usage":{"total_tokens":3093,"prompt_tokens":1048,"completion_tokens":2045,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":664,"completion_tokens_details":{"reasoning_tokens":1926}},"tokens_in":664,"tokens_out":2045,"duration_ms":13251,"temperature":1.0,"reasoning_tokens":1926,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-14T04:53:05.825871+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"If an independent measurement established that the chargino and the lightest neutralino are split by more than a few GeV, the chargino would decay to visible jets or leptons, and the mono-b final state assumed here would not be the signature; that single observation would falsify the reach estimate.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"It presents the earlier mono-t single-stop analysis at the HL-LHC that motivates this mono-b study in the same simplified natural-SUSY framework."},{"cited_title":"Goncalves, D","cited_arxiv_id":null,"evidence_quote":"It computes single-stop production in different SUSY models, supporting the claim that the electroweak channel distinguishes higgsino-like from wino-like charginos."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"It supplies the Monte Carlo event generator used to produce parton-level signal and background events."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"It provides the NLO QCD correction used as the K-factor of 1.4 for the single-stop cross section."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"It supplies the NLO stop-pair cross section used as the comparison baseline for pair production."},{"cited_title":"Goncalves, D","cited_arxiv_id":null,"evidence_quote":"It computes sparticle masses, couplings, and branching ratios for the benchmark spectra."},{"cited_title":"Athron et al","cited_arxiv_id":null,"evidence_quote":"It provides the detector simulation used to apply analysis cuts and estimate efficiencies."},{"cited_title":"Djouadi, M","cited_arxiv_id":null,"evidence_quote":"It supplies the analysis framework used to implement event selection and derive the statistical significance."}],"review_version":1}