{"id":"c0906627-6ed7-46ce-8ba4-d1620fc5d5ed","arxiv_id":"1908.06805","paper_version":3,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"A feasibility proposal to measure vector-boson scattering at LHCb using a single tagged forward jet and two same-sign muons, with an estimated combined cross section near 0.35 fb.","lead":"This paper proposes measuring vector-bon scattering at the LHCb experiment by detecting one forward jet and two same-sign muons instead of the usual two jets. It computes event rates and argues that future LHCb luminosity could make such a measurement possible, though the study is exploratory.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Even at 100% efficiency, the quoted yields do not put an EW-only measurement in reach: ~30 EW vs ~390 QCD events at 300/fb gives about 1.5 sigma, so the central claim overreaches the paper's own numbers.","rationale":"The reader's weakest-assumption point is that detector-level effects are unquantified, and the author explicitly brackets them. That is a valid concern. However, the more fundamental and internal problem is that even in the idealized limit of 100% reconstruction efficiency, the paper's own cross-section numbers give too few EW events for the claimed 'EW contribution on its own' to be in reach: about 1.5 sigma at 300/fb in a simple counting test. This shifts the emphasis from 'we need detector simulation' to 'the theoretical numbers themselves do not demonstrate the headline feasibility claim.' The paper remains valuable as an exploratory proposal, and a dedicated optimization or significance projection could rescue the conclusion, so I retain the reader's CONDITIONAL verdict. I do not reject the paper because the LO calculation and the proposed signature are legitimate and original; the issue is the strength of the concluding inference, not the correctness of the computation.","tokens_in":6847,"tokens_out":8927,"duration_ms":107658,"concrete_test":"Using the quoted cross sections from Table I and Eq. (15), compute the expected event counts N_total and N_EW for L = 50 and 300/fb under the selection in Eqs. (1)-(4), assuming 100% efficiency. Then repeat using the high-pT,j (e.g., pT,j > 100 and > 200 GeV) and low-y_mu (e.g., 2.0 < y_mu < 2.5) bins implied by Figs. 3 and 4, and evaluate the significance z = N_EW/sqrt(N_QCD) for the EW component alone. If no bin reaches z >= 3, the statement that the EW contribution on its own can be in reach is not supported even before detector-level effects are included.","verdict_should_be":"UNCHANGED","load_bearing_attack":"Taking the quoted cross sections at face value and assuming 100% reconstruction and trigger efficiency, the claimed reach is not reproduced by the paper's own numbers. From Table I and Eq. (15), the e/mu same-sign sample at 300/fb has roughly 420 events, of which about 30 (approximately 7.5%) are EW. A counting test against the QCD-only hypothesis gives only 30/sqrt(390) ≈ 1.5 sigma; at the 50/fb scenario it is below 1 sigma. The differential distributions in Figs. 3 and 4 show that the EW fraction grows with pT,j and falls with y_mu, but no integrated yields or significances in those bins are given, so the reader cannot tell whether the 'EW contribution on its own' is actually measurable. The caveat that the selection is pessimistic and could be optimized is not enough: no quantitative optimization is presented. Detector effects, which the author explicitly leaves out, would only make the situation worse. This is not a criticism of the LO computation, but of the inference from a 0.35 fb inclusive cross section to the claim that the EW component is in reach for high-luminosity LHCb runs.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper proposes measuring vector-boson scattering (VBS) at the LHCb experiment using a signature with one forward jet and two same-sign muons, exploiting LHCb's forward coverage. It defines an event selection, computes leading-order cross sections and differential distributions for the electroweak (O(α^6)) and QCD (O(α^4 α_s^2) / O(α^4 α_s)) contributions to pp→μ+μ+j+X using Recola and MoCaNLO, and argues that both the combined QCD+EW process and the EW component alone could be measured in high-luminosity LHCb runs.","tokens_in":7055,"tokens_out":4702,"duration_ms":54222,"significance":"The proposal is original and, if realizable, would provide a forward-region VBS measurement that is independent of ATLAS and CMS. The LO computation is standard and transparent: it is a direct phase-space integration with no fitted parameters, and the paper quotes Monte Carlo integration errors and scale uncertainties. These are genuine strengths. The weakness is that the central feasibility claim rests on two unquantified pillars: the statistical significance implied by the paper's own cross sections, and the detector/trigger/fake-lepton performance, which the author explicitly defers to a future experimental study. As a result, the paper identifies a promising signature but does not yet demonstrate that the EW component is measurable.","major_comments":[{"comment":"The quoted cross sections do not support the Discussion's claim that the EW contribution on its own can be in reach. From Table I and Eq. (15), the inclusive e/μ same-sign sample at 300 fb^-1 has about 420 events, of which roughly 30 are EW and 390 are QCD. A counting test against a QCD-only hypothesis gives 30/sqrt(390) ≈ 1.5 sigma, and at 50 fb^-1 it is below 1 sigma. Please provide a quantitative significance statement, including binned projections such as the high-pT,j region of Fig. 3 where the EW fraction reaches about 20%, or revise the conclusion to match the statistical reach of the presented numbers.","section":"Table I, Eq. (15), Discussion"},{"comment":"The feasibility claim depends on the unverified assumption that LHCb can trigger on and reconstruct the mu+ mu+ j signature with sufficient efficiency and that fake or non-prompt lepton backgrounds can be controlled. The paper states that such optimizations \"require experimental knowledge on efficiencies, event yields, fake backgrounds and therefore go beyond this exploratory theoretical work,\" but no efficiency or fake-rate assumptions are supplied. Without any detector-level modeling or explicit efficiency assumptions, the step from a 0.35 fb inclusive cross section to the statement that a measurement is \"in reach\" is not established. Please include explicit assumptions or restrict the claim to a theoretical identification of a promising signature.","section":"Measurement strategy, paragraph after Eq. (4)"}],"minor_comments":[{"comment":"The phrase \"two anti-muons\" should be clarified as \"two positively charged muons\" to avoid confusion with antimuons in the experimental sense.","section":"Measurement strategy"},{"comment":"The relations sigma(WW→e+mu+) ≈ 2 sigma(WW→mu+mu+) and sigma(ZZ→e+mu+) ≈ 2 sigma(ZZ→mu+mu+) rely on identical-particle symmetry and the massless-lepton limit; this should be stated explicitly at that point.","section":"Eq. (15)"},{"comment":"The lower panels are labeled \"Sumδ [%]\" but they show the EW fraction of the sum; the label should be changed to something unambiguous such as \"EW fraction of total\".","section":"Figs. 3 and 4"},{"comment":"The sentence calling the summed cross section \"the physical cross section\" should note that the interference of order O(α^5 α_s) is neglected, so the sum is approximate even though the interference is expected to be small.","section":"Numerical results, third paragraph"},{"comment":"Reference [13] is listed as \"to be published (2020)\"; this should be updated with the current status of the dedicated experimental study, or removed if no longer available.","section":"References"},{"comment":"The statement that electrons and muons are identical in the computation should be accompanied by a note that experimental reconstruction and trigger efficiencies differ, which is relevant for the flavor-combination argument in Eq. (15).","section":"Footnote [27]"}],"recommendation":"major_revision","confidential_remarks":"The manuscript is within scope for a phenomenological journal. The main issue is the mismatch between the quantitative results and the headline claim of measuring the EW component alone. A major revision that adds a significance statement and explicit experimental assumptions, or that tempers the conclusion accordingly, would make the claim defensible."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Colleague,\n\nThe core idea is genuinely new as far as I know: instead of the usual two-forward-jet VBS tag, tag one jet in the LHCb acceptance plus two same-sign muons. That is a sensible adaptation to an asymmetric detector and opens a kinematic region (large lepton rapidity) that ATLAS and CMS don't cover. The LO calculation is clean: standard tools, stated integration errors, scale uncertainties, and an explicit list of what is left out (detector efficiencies, fake backgrounds, NLO corrections, a companion experimental study). Citation use is fair; the self-citations are for interference size and PDF uncertainties, not inputs that define the result.\n\nNow the soft spots. The stress-test arithmetic is correct and it matters. From Table I, the total muon-channel cross section is ~0.35 fb, with ~0.026 fb (7.5%) EW. At 300/fb that is roughly 30 EW events against ~390 QCD. A counting test separating EW from the QCD-only hypothesis gives about 1.5 sigma, before any efficiency or fake-rate penalty, and the author himself calls the selection pessimistic. At 50/fb it is below 1 sigma. So the Discussion claim that 'the EW contribution on its own can be in reach' does not follow from the paper's own numbers. The differential plots show the EW fraction rising toward 20% at high jet pT, but no per-bin yields are given, so you cannot tell whether a kinematic cut would rescue the significance. The combined QCD+EW measurement may be plausible, but the standalone EW claim is not supported.\n\nThis is not a fatal flaw for the idea, and the paper is honest about what it omits. A serious referee would ask for at least a rough trigger-efficiency estimate and a comment on whether LHCb has a same-sign dimuon trigger, but those are exactly the points flagged as future work.\n\nBottom line: this is a good idea paper, not a measured result. The original tagging strategy and the LO inputs are worth having in the literature. I'd send it to peer review, with the expectation that the final version either walks back the EW-reach claim or adds the integrated significance numbers that support it.","headline":"A genuinely new one-jet VBS tag for LHCb with clean LO numerics, but the claim that the EW component alone is in reach overstates the paper's own yields (~1.5 sigma at 300/fb).","tokens_in":7579,"tokens_out":2520,"would_cite":false,"duration_ms":24473,"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 LHCb can measure vector-boson scattering in its forward region by tagging a single jet together with two same-sign muons, making a combined electroweak-plus-QCD measurement, and possibly the electroweak component…","keywords":["vector boson scattering","LHCb","same-sign dileptons","forward physics","electroweak production","leading-order cross section","same-sign WW scattering","forward jet tagging"],"falsifier":"Run-3 LHCb data or a detector-level simulation could settle it: if the trigger and reconstruction efficiency for the $\\mu^+\\mu^+ j$ selection is far below the level needed to retain a usable fraction of the predicted ~0.35 fb (muon-only) or ~1.4 fb (all flavour/charge) yield, the measurement would not be in reach. Concretely, at 300 fb$^{-1}$ the electroweak component predicts only about 8 $\\mu^+\\mu^+ j$ events before detector effects; an efficiency below ~20% would leave fewer than two EW events and make a standalone EW measurement impossible.","tokens_in":6619,"feed_emoji":"⚛️","tokens_out":9005,"duration_ms":83983,"temperature":0.7,"pith_summary":"The paper proposes that LHCb, despite its forward-only and asymmetric detector, can measure vector-boson scattering (VBS) by tagging one jet and two same-sign muons instead of the usual two jets. It computes leading-order cross sections for the $\\mu^+\\mu^+ j$ final state and finds the electroweak and QCD contributions to be $0.0258~\\mathrm{fb}$ and $0.3217~\\mathrm{fb}$, respectively, with the same-sign WW channel the dominant electroweak piece. Extrapolating over lepton flavours and charges gives roughly $1.4~\\mathrm{fb}$ total, of which about $0.1~\\mathrm{fb}$ is electroweak. The paper concludes that at $50\\text{--}300~\\mathrm{fb}^{-1}$ both a combined QCD-plus-EW measurement and a standalone EW measurement are within reach, offering a forward-region test of the electroweak sector complementary to measurements at the central LHC experiments.","feed_headline":"LHCb can measure vector-boson scattering with one jet and two muons","feed_subtitle":"A forward jet plus two same-sign muons could make the electroweak signal visible at high-luminosity LHCb.","key_machinery":"The central object is the inclusive signature $pp \\to \\mu^+\\mu^+ j + X$, selected with a forward single-jet tag: one anti-$k_T$ jet with $p_T > 20$ GeV and $2.2 < \\eta < 4.2$, two same-sign muons with $p_T > 20$ GeV and $2.0 < y < 4.5$ separated from the jet by $\\Delta R > 0.5$, and a veto on any extra lepton with $2.0 < \\eta < 4.5$. This signature replaces the conventional two-tag-jet VBS topology and exploits LHCb's forward muon coverage. Cross sections are computed at leading order with the Recola matrix-element generator and the MoCaNLO integrator, using the complex-mass scheme for resonant gauge bosons and the NNPDF31 parton distribution set; the anti-$k_T$ algorithm with $R=0.4$ defines the jet.","core_discovery":"The central claim is that VBS can be observed at LHCb in the forward region using an event selection that deliberately does not reconstruct the full VBS topology. Instead of requiring two high-rapidity tagging jets and central bosons, one tags a single forward jet ($p_T > 20$ GeV, $2.2 < \\eta_j < 4.2$) together with two same-sign anti-muons ($p_T > 20$ GeV, $2.0 < y < 4.5$, $\\Delta R > 0.5$ from the jet), vetoing additional leptons in the forward region. In this selection, the same-sign WW process dominates the electroweak signal, while WZ and ZZ contribute at the percent level and are suppressed by the lepton veto. The summed electroweak cross section is $0.0258~\\mathrm{fb}$ against $0.3217~\\mathrm{fb}$ of irreducible QCD background for $\\mu^+\\mu^+ j$, and the electroweak fraction grows with jet transverse momentum and at low muon rapidity. The author therefore argues that a combined QCD+EW measurement, and even the EW component alone, is in reach for the high-luminosity LHCb runs.","pith_inferences":["If the detector-efficiency and fake-background assumptions are confirmed by a dedicated LHCb study, the yield projections imply that the first forward-region VBS observation could be made with early high-luminosity data rather than only in the far future.","The single-tag, same-sign-dilepton strategy could be adapted to search for new physics in the forward region, since the electroweak fraction is largest at high jet $p_T$ and low muon rapidity where anomalous couplings would show up first.","The same selection could be applied to the $e^+e^+$ and $e^+\\mu^+$ channels with essentially identical cross sections in the massless-lepton limit, which would allow a forward-region lepton-universality check in VBS.","An EW-only differential measurement would supply a high-rapidity anchor for global electroweak fits, a region where next-to-leading-order corrections are known to be large."],"forward_implications":["A combined measurement of the QCD and electroweak contributions to $pp \\to \\mu^+\\mu^+ j + X$ is in reach at LHCb's high-luminosity runs, with a total selected cross section of about $0.35~\\mathrm{fb}$ for the muon-only channel.","The electroweak component alone is separable: it is about 8% of the inclusive sample and rises to roughly 20% at high jet $p_T$, so phase-space cuts can improve the signal-to-background ratio.","Including all lepton flavour and charge combinations yields about $1.4~\\mathrm{fb}$ total, of which about $0.1~\\mathrm{fb}$ is electroweak, multiplying the available statistics.","Because LHCb covers forward rapidities, such a measurement would probe VBS kinematics not accessible to the central LHC experiments and would provide an independent test of the electroweak sector."],"supporting_citations":[{"why":"Provides the large NLO electroweak corrections at forward rapidity and establishes that signal and background are ambiguous at NLO, motivating a combined measurement.","marker":"[11]"},{"why":"Supplies the relations between lepton flavour and charge channels used to extrapolate the mu+mu+ cross section to the full ~1.4 fb yield.","marker":"[12]"},{"why":"The planned dedicated experimental LHCb study that would validate trigger efficiencies, event yields, and fake backgrounds; the feasibility conclusion explicitly depends on it.","marker":"[13]"},{"why":"Introduces the complex-mass scheme used to treat W/Z resonances with gauge-invariant widths.","marker":"[17]"},{"why":"The Recola code that evaluates all leading-order matrix elements for the signal and background processes.","marker":"[19]"},{"why":"The NNPDF31 parton distribution set used for all predictions.","marker":"[23]"},{"why":"The anti-kT jet algorithm with R=0.4 that defines the tagging jet.","marker":"[24]"}],"fun_headline_variants":["Single forward jet plus same-sign muons opens VBS at LHCb","Forward jet and two same-sign muons could reveal vector-boson scattering","LHCb's forward reach enables one-jet VBS tag","One jet, two same-sign muons: LHCb can see electroweak scattering","High-luminosity LHCb can isolate vector-boson scattering with one jet"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The feasibility conclusion rests on the untested assumption that LHCb can trigger on and reconstruct the forward same-sign-dimuon-plus-jet signature with sufficient efficiency and can keep fake and non-prompt lepton backgrounds under control; the paper explicitly leaves this experimental verification to a future study.","fun_headline_variants_meta":{"raw":{"variants":["Single forward jet plus same-sign muons opens VBS at LHCb","Forward jet and two same-sign muons could reveal vector-boson scattering","LHCb's forward reach enables one-jet VBS tag","One jet, two same-sign muons: LHCb can see electroweak scattering","High-luminosity LHCb can isolate vector-boson scattering with one jet"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000911,"raw_usage":{"total_tokens":3893,"prompt_tokens":903,"completion_tokens":2990,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":519,"completion_tokens_details":{"reasoning_tokens":2887}},"tokens_in":519,"tokens_out":2990,"duration_ms":21385,"temperature":1.0,"reasoning_tokens":2887,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-14T12:33:51.615606+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Run-3 LHCb data or a detector-level simulation could settle it: if the trigger and reconstruction efficiency for the $\\mu^+\\mu^+ j$ selection is far below the level needed to retain a usable fraction of the predicted ~0.35 fb (muon-only) or ~1.4 fb (all flavour/charge) yield, the measurement would not be in reach. Concretely, at 300 fb$^{-1}$ the electroweak component predicts only about 8 $\\mu^+\\mu^+ j$ events before detector effects; an efficiency below ~20% would leave fewer than two EW events and make a standalone EW measurement impossible.","supporting_citations":[{"cited_title":"Kenzie and M","cited_arxiv_id":null,"evidence_quote":"The planned dedicated experimental LHCb study that would validate trigger efficiencies, event yields, and fake backgrounds; the feasibility conclusion explicitly depends on it."}],"review_version":1}