{"id":"4797e78d-9c4d-4312-a114-aadfa1a05143","arxiv_id":"2411.08143","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":4,"one_line_summary":"Simulated ILC data at 500 GeV with 1000 fb^-1 would exclude vector-like leptons up to about 100-180 GeV for small mass splittings, and across the whole studied range for a 100 GeV splitting, at a Yukawa coupling of 0.1.","lead":"This paper uses Monte Carlo simulations of a proposed 500 GeV electron-positron collider, the ILC, to estimate how well it could detect dark matter produced through vector-like leptons decaying to electrons and invisible particles. It reports projected 95% confidence exclusion limits on the vector-like lepton mass, and argues the ILC could probe a nearly degenerate mass region that the LHC cannot reach.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The 10 GeV electron pT cut in Table 2 can remove essentially all DeltaM=5 signal, since the decay electron has p^* < 5 GeV in the parent rest frame; the quoted 100 GeV exclusion may be an artifact of an unquantified acceptance tail.","rationale":"The reader's weakest assumption was that the ILD Delphes card reproduces detector response for soft electrons and missing energy in the DeltaM=5 signal. My concern is more fundamental: even with a perfect detector, the kinematic relation p* approximately equal to DeltaM implies that the decay electrons in the DeltaM=5 scenario have pT around 5 GeV in the parent rest frame, and the 10 GeV transverse momentum cut removes them unless the parent L receives a substantial transverse boost from ISR or beamstrahlung. The paper does not quantify this acceptance, does not show the DeltaM=5 signal distribution, and does not report the corresponding efficiency. If the acceptance is negligible, the claimed exclusion of M_L below 100 GeV for DeltaM=5 is not supported, which weakens the central message about reaching quasi-degenerate dark matter. I agree with the reader that the quantitative limits should be treated as preliminary, but the specific kinematic issue is sharper than a generic detector-simulation concern. The verdict should remain conditional: the DeltaM=10 and DeltaM=100 results may survive, but the DeltaM=5 limit needs a dedicated check and likely a revision of the selection or the claim.","tokens_in":1009,"tokens_out":901,"duration_ms":214089,"concrete_test":"Regenerate the DeltaM=5 signal with WHIZARD+Delphes using the paper's setup and compute the efficiency of the full selection of Table 2 for M_L=100 and 200 GeV, counting how many events have both electrons with pT > 10 GeV. If the efficiency is below about 1e-3, the 95% CL exclusion claimed in Fig. 6a cannot be reproduced and the claim fails. As a control, lower the pT cut to 5 GeV and repeat; if the DeltaM=5 limit shifts substantially, the pT threshold is the driver.","verdict_should_be":"UNCHANGED","load_bearing_attack":"In the rest frame of L to e chi, for DeltaM = M_L - M_chi = 5 GeV, the electron momentum is p^* = sqrt((M_L^2 - (M_chi + m_e)^2)(M_L^2 - (M_chi - m_e)^2)) / (2 M_L), which is less than 5 GeV for all M_L. A boost along the beam does not increase transverse momentum, so for events in which the L pair is produced back-to-back along the beam (the dominant no-ISR configuration), each electron has pT well below 10 GeV. The Table 2 pre-selection and final selection require pT^e > 10 GeV for every electron. Thus the DeltaM=5 signal can pass only if ISR/beamstrahlung boosts the L system transversely enough to push the electrons above 10 GeV. For M_L=200 GeV, the available boost is too small; for M_L below about 100 GeV the required boost is less extreme but still yields a very small acceptance. The paper never reports the signal efficiency for any mass and never shows a DeltaM=5 kinematic distribution (Fig. 5 only shows DeltaM=10, 20, 100). If the acceptance is close to zero, the 95% CL exclusion for M_L below 100 GeV in Fig. 6a is not a limit on the model but an artifact of an empty or tiny signal template being normalized. This is an internal-consistency issue, not a detector-simulation nuance, and it directly affects the central claim that the ILC can probe the quasi-degenerate region with DeltaM=5.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript presents a fast-simulation study of vector-like lepton (L) pair production at the ILC with sqrt(s)=500 GeV and 1000 fb^-1 in the lepton portal dark matter model, where the dark matter is a scalar chi and the L decays to an electron and chi. Signal and background samples are generated with WHIZARD, PYTHIA6, and Delphes with the ILD card. A cut-based event selection followed by a shape-based CLs analysis on missing transverse energy yields 95% CL expected exclusion limits on the vector-like lepton mass for mass splittings DeltaM=5, 10, and 100 GeV at Yukawa coupling lambda_L=0.1. The paper claims the ILC can exclude M_L below 100 GeV for DeltaM=5, below 180 GeV for DeltaM=10, and the entire studied mass range for DeltaM=100, thereby probing the quasi-degenerate region that the LHC cannot access.","tokens_in":11829,"tokens_out":13292,"duration_ms":167417,"significance":"If correct, the result would establish a unique role for the ILC in probing compressed lepton-portal dark matter scenarios, complementing LHC searches. The paper has strengths: the simulation chain is described with generator versions, the beam polarization and beamstrahlung are included, and the CLs procedure is cited. However, the analysis omits systematic uncertainties, presents an incomplete background list, and does not report signal efficiencies, so the projected limits cannot currently be taken at face value.","major_comments":[{"comment":"The manuscript does not report signal acceptance or event yields after the final selection for any mass point. For the DeltaM=5 scenario, the electron from L->e chi has p* < 5 GeV in the L rest frame, and for M_L around 200 GeV the maximum lab-frame pT (from the boost of the L) is about 9.9 GeV, so the pT^e > 10 GeV cut of Table 2 removes essentially the entire signal; the paper never shows a DeltaM=5 kinematic distribution (Fig. 5 only covers DeltaM=10, 20, 100, and 199 at M_L=200). Since the DeltaM=5 exclusion in Fig. 6a is a central claim, the authors must provide the signal efficiency as a function of M_L and demonstrate that the exclusion is not driven by an empty or tiny signal template.","section":"Sec. 3.1, Table 2, Fig. 6a"},{"comment":"The background simulation omits several processes that can yield two electrons plus large missing transverse energy at e+e- colliders: single-W production e+e- -> e nu W with W->e nu, radiative Bhabha scattering with the photon lost in the beam pipe, and two-photon processes. These backgrounds must be included or their neglect justified quantitatively, since they can contribute in the same EmissT region and affect the limit.","section":"Sec. 3.2, Table 1"},{"comment":"No systematic uncertainties are incorporated in the limit-setting procedure. At 1000 fb^-1 the statistical uncertainties are small, so the 95% CL exclusion boundaries will be sensitive to background normalization uncertainties and detector response uncertainties such as energy scale and resolution. The authors should include nuisance parameters in the CLs calculation or, at a minimum, discuss the expected impact on the mass reach.","section":"Sec. 5"},{"comment":"The claim that the LHC cannot effectively probe DeltaM <= 80 GeV is based on Ref. [30], which is coauthored by one of the present authors. This comparison should be cross-checked against up-to-date LHC searches, for example the CMS and ATLAS vector-like lepton searches, to assess the uniqueness claim independently rather than relying on a self-referential paper.","section":"Sec. 5, Ref. [30]"}],"minor_comments":[{"comment":"The two subsections report different WHIZARD versions (3.1.4 in Sec. 3.1 and 3.4.1 in Sec. 3.2); this is likely a typo and should be corrected.","section":"Sec. 3.1 vs Sec. 3.2"},{"comment":"The references contain several formatting errors: [5] and [6] are not correctly formatted, [15] exhibits a unicode issue, and [49] contains a stray 'PIG' in the title.","section":"References"},{"comment":"The captions of Figures 3 and 5 refer to 'the pre-selection cuts listed in table 2' but the figures are placed at the end of Section 4; consider clarifying which selection stage each figure corresponds to.","section":"Sec. 4 and captions of Figs. 3 and 5"},{"comment":"In Table 2, the pre-selection and final selection columns are identical for the first three rows, which makes it difficult to see which cuts are applied at which stage; consider listing only the added final-selection cuts.","section":"Table 2"}],"recommendation":"major_revision","confidential_remarks":"The paper is a straightforward Monte Carlo projection whose main novelty is the compressed-mass region. The self-reference to Ref. [30] and the omission of systematics and signal-efficiency reporting make it premature for publication in its current form. The analysis could be brought to publishable quality with additional validation, but as it stands, the central claim is not fully supported by the reported information."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Dear [Colleague],\n\nYou should know about this paper if you track ILC physics cases or lepton portal dark matter. It's a Monte Carlo projection, not a measurement, but it's the first ILC-specific exclusion study for this simplified model with three mass splittings (5, 10, 100 GeV). The simulation chain is standard: WHIZARD with ISR/beamstrahlung, PYTHIA showering, Delphes with the ILD card, and a CLs limit using the EmissT shape. That is all done carefully enough for a sensitivity study.\n\nThe genuinely new result is the claim that with 1000 fb^-1 at 500 GeV and lambda_L=0.1, the ILC would exclude ML up to 100 GeV for DeltaM=5, 180 GeV for DeltaM=10, and the full tested range for DeltaM=100. The LHC comparison comes from Ref. [30], coauthored by one of the present authors, but the limit computation itself is independent, so the circularity burden is minor.\n\nThe soft spots are the usual ones for this genre: no systematic uncertainties, a background list that omits single-W, e-gamma, and gamma-gamma processes, and no public code or data. More specifically, there is no signal efficiency table and no DeltaM=5 kinematic plot; Figure 5 only shows DeltaM=10, 20, 100. That is a transparency problem for the narrow-splitting claim.\n\nI want to disagree with a specific worry that the 10 GeV pT cut kills the DeltaM=5 signal. That would matter if the L pair were produced back-to-back along the beam, so the decay electrons inherit only the small p* (~5 GeV). But for the mass range where the DeltaM=5 exclusion is claimed (ML up to 100 GeV), the L is highly boosted at 500 GeV CM; a 100 GeV L has momentum ~229 GeV. The differential production cross-section has substantial weight at large angles, so the electron pT is typically far above 10 GeV. The stress-test's assumption that the beam-aligned configuration dominates is not correct. Still, showing the DeltaM=5 distribution would settle it.\n\nWho is this for? People building the ILC physics case and model-builders who want a quick handle on lepton portal sensitivities. A serious referee should look at it, mainly to demand systematics and a background-completeness check, and to see the DeltaM=5 plots. The qualitative statement that the ILC can probe the quasi-degenerate region is likely right; the precise mass limits should be treated as preliminary.\n\nRecommendation: send to peer review. It's a solid, if narrow, sensitivity study that deserves scrutiny.\n\nBest,\n[Your name]","headline":"A plausible ILC sensitivity projection for lepton portal dark matter; the narrow-splitting exclusion is believable, though the missing DeltaM=5 plots and systematics need attention.","tokens_in":12476,"tokens_out":5759,"would_cite":true,"duration_ms":52054,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":null,"created_at":"2026-08-12T21:55:47.371637+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":null,"supporting_citations":[],"review_version":1}