{"id":"5d5c3fa0-2061-46da-a841-0a8b5a23d6a1","arxiv_id":"2412.06297","paper_version":1,"verdict":"UNVERDICTED","confidence":"HIGH","novelty_score":0.0,"correctness_risk":"low","formal_verification":"none","parameter_count":0,"one_line_summary":"A review of recent ATLAS and CMS prompt searches for feebly interacting particles, reporting updated exclusion limits without any new experimental result.","lead":"This paper is a conference summary of eight recent ATLAS and CMS searches for feebly interacting particles at the LHC. It reviews new exclusion limits on dark mesons, heavy neutral leptons, dark matter, and dark photons, but presents no new data or analysis.","discovery_kind":"review","skeptic_critique":{"model":"deepseek-v4-flash","headline":"No significant objection identified: this proceedings faithfully reports eight ATLAS/CMS searches; the central claim inherits the external credibility of those analyses and no internal error threatens it.","rationale":"The reader's verdict of UNVERDICTED is appropriate. A proceedings paper restates the experimental results without adding new derivations or data, so its correctness risk is low but its independent verifiability is nil. The weakest point is indeed the reliance on the eight underlying analyses; however, that is an external dependency, not an internal flaw. The claim 'first collider-based constraints' is specific but plausible, and no obvious contradiction appears. My recommended action is to leave the verdict unchanged.","tokens_in":6853,"tokens_out":3894,"duration_ms":38189,"concrete_test":"Check the 'first collider-based constraints' assertions in §2 by confirming from the cited papers that no earlier collider search covers the same model and parameter range; in particular verify that ATLAS JHEP 09 (2024) 005 is the first dark-meson collider search and CMS JHEP 06 (2024) 123 the first prompt HNL search with hadronic tau decays above the W mass. Also correct the 'massless dark photon' wording in the [15] paragraph to 'massive dark photon'.","verdict_should_be":"UNCHANGED","load_bearing_attack":"No load-bearing concern found. The paper is a conference proceedings that summarizes eight published or arXiv-accepted ATLAS and CMS searches and draws no independent quantitative conclusion. Its central claim—that the exclusion limits significantly extend probed parameter space and in some cases are first collider constraints—is a faithful restatement of the cited results. The only inaccuracy I noticed is in the paragraph discussing Ref. [15]: the minimal dark photon model is described as 'resulting in a massless dark photon,' although the search is for dimuon resonances at 1.1–2.6 and 4.2–7.9 GeV, which requires a massive dark photon. This appears to be a typo and does not affect the reported limits or the summary claim.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper is a conference proceedings contribution by J. Knolle on behalf of the ATLAS and CMS Collaborations, reviewing eight recent prompt searches for feebly interacting particles at the LHC using the 2015–2018 13 TeV dataset of roughly 140 fb–1. The covered searches address dark mesons decaying to top and bottom quarks, heavy neutral leptons in trilepton and Z′-mediated channels, simplified dark matter models with s-channel mediators, a dark Higgs model with associated W-boson-pair production, a 2HDM-plus-pseudoscalar-mediator combination, low-mass dimuon resonances using scouting triggers, and Higgs-boson decays to a photon plus a massless dark photon. For each selected analysis, the paper reports the main exclusion limits, expected and observed 95% CL intervals, and the considered model parameters. The central claim is that the presented results significantly extend the probed parameter space and, in some cases, provide the first collider constraints for the considered models.","tokens_in":7099,"tokens_out":4377,"duration_ms":44323,"significance":"The paper is a compact, well-organized survey of current ATLAS and CMS prompt searches for feebly interacting particles. Its strength is its faithful, concise reporting of the eight cited analyses, with correct attribution to the original papers and appropriate reproduction of their figures. The paper contains no new derivation or independent calculation, so its scientific value rests on the accuracy of the summary and on the trustworthiness of the underlying experimental papers. As a proceedings contribution, it serves the community as a useful reference point for the status of these searches. The claim that the limits extend the parameter space and include first collider constraints is a faithful restatement of the cited results; the paper does not overreach beyond what the original analyses report.","major_comments":[],"minor_comments":[{"comment":"The sentence describing the minimal dark photon model in the scouting-trigger dimuon search says that the model results in a massless dark photon. This is a typo: the search targets dimuon resonances with masses of 1.1–2.6 and 4.2–7.9 GeV, which requires a massive dark photon. Please correct the wording to state that the dark photon is massive, and if appropriate clarify the mass-generation mechanism (e.g., a dark Higgs or Stueckelberg mass term).","section":"Section 2, paragraph on Ref. [15]"},{"comment":"The abstract states that the results are based on an integrated luminosity of “about 140 fb–1”. The individual analyses use 138 or 139 fb–1; while “about 140” is acceptable for a proceedings, adding a brief footnote or parenthetical listing the exact luminosities of the individual analyses would remove potential ambiguity for readers who compare the cited papers.","section":"Abstract and introduction"},{"comment":"In the heavy neutral lepton and Z′ sections, comparison figures are cited as Ref. [20], which is a CMS review article rather than a primary search. The text already says “various analyses” and “different production channel,” but it would be clearer to state explicitly that the comparison is taken from the review, not from the search under discussion, to avoid any impression that the new limits are being directly compared with one another.","section":"Section 2, HNL and Z′ paragraphs"}],"recommendation":"minor_revision","confidential_remarks":"This is a standard LHCP proceedings paper summarizing published ATLAS and CMS results. The only substantive issue is the incorrect “massless dark photon” statement in the scouting-trigger section, which should be corrected before publication. There are no concerns about novelty, scope, or citation practice; the paper is an accurate and useful survey. I recommend minor revision."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"You asked about Knolle's LHCP proceedings write-up, arXiv:2412.06297. The short version: it's exactly what it says on the tin—a review of eight published ATLAS and CMS searches for prompt feebly interacting particles, with no new analysis, data, or derivation. The reader's report is right: novelty is zero, but the summary is accurate and the claims are faithful restatements of the cited results.\n\nWhat it does well: the organization is clear, the model-by-model structure (dark mesons, HNLs, DM mediators, dark photons) is easy to follow, and the figures are well chosen. For someone coming into the field, it gives a quick, reliable map of what ATLAS and CMS have done in this corner of Run 2. The paper also correctly flags where a search is a first collider constraint (e.g., the dark meson search and exclusive tau-coupling HNL search), and it doesn't oversell beyond what the cited papers say.\n\nThe main soft spot is the one the stress-test caught: the paragraph on Ref. [15] describes the minimal dark photon model as \"resulting in a massless dark photon,\" which is wrong in context—the search targets dimuon resonances at 1.1–2.6 and 4.2–7.9 GeV, so the dark photon is massive by construction. It reads like a typo (they meant massless mixing or something else) and doesn't affect any of the reported limits, but it should be fixed before publication. Minor.\n\nThe other caveat is not a flaw in this genre: the paper takes the statistical procedures and backgrounds of the eight underlying analyses on trust, citing them. That's appropriate for a proceedings review; independent verification belongs in the original papers. The reader's weakest assumption is real but applies to any such summary.\n\nOverall, this is a solid, honest review. It's not a research contribution, and nobody should cite it as a primary source for a physics result. But as an overview for graduate students or theorists wanting the current experimental status in prompt FIP searches, it's useful and accurate. I'd bring it to a reading group for that purpose, not because it changes anything.\n\nRecommendation: if this came through a peer-review route (as some proceedings do), send it to a referee—it's the kind of descriptive paper that a knowledgeable editor can accept after checking the typo. It deserves a light-touch review, not a desk reject.","headline":"A competent, faithful proceedings summary of eight ATLAS/CMS prompt searches; no new results but a useful map for non-experts, with one minor typo about the dark photon model.","tokens_in":7394,"tokens_out":993,"would_cite":false,"duration_ms":11640,"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":"This review of eight ATLAS and CMS searches claims that the 2015-2018 LHC data at 13 TeV now exclude previously unexplored masses and couplings for dark mesons, heavy neutral leptons, dark matter mediators, and dark photons.","keywords":["feebly interacting particles","prompt signatures","heavy neutral leptons","dark mesons","dark photons","dark matter","ATLAS and CMS","LHC Run 2"],"falsifier":"If any one of the eight analyses were re-run with a corrected background model that moved its 95% CL upper limit above the boundary the paper shows as excluded, the claim of extended coverage would be wrong for that model. A concrete place to look is the CMS scouting dimuon search: a narrow resonance with local significance above 5 $\\sigma$ anywhere between 1.1 and 7.9 GeV in the same 140 $fb^{-1}$ data would contradict the dark photon exclusion presented in Fig. 4.","tokens_in":6691,"feed_emoji":"🔍","tokens_out":11434,"duration_ms":107207,"temperature":0.7,"pith_summary":"This paper is a summary of eight recent ATLAS and CMS searches for promptly produced feebly interacting particles, using the full 2015-2018 LHC Run 2 dataset of 13 TeV proton-proton collisions with an integrated luminosity of about 140 $fb^{-1}$. It seeks to establish that these searches jointly extend the excluded parameter space for four classes of models: dark mesons decaying to top and bottom quarks, heavy neutral leptons, dark matter in several mediator scenarios, and dark photons. In some cases the paper reports that the searches give the first collider-based constraints for the considered model. If the claims are correct, the low-mass windows that strong-coupling searches cannot reach are now being closed by prompt-signature searches, and the combination of complementary final states is the reason the coverage improves.","feed_headline":"Eight LHC analyses extend limits on feebly interacting particles","feed_subtitle":"Run 2's 140 fb^-1 dataset now rules out new mass ranges for dark mesons, heavy neutrinos, dark photons, and dark matter.","key_machinery":"The central mechanism is the 'prompt signature' assumption together with the shared Run 2 dataset: each of the eight analyses selects events where the new particle is produced and decays at the interaction point, so the experimental handle is the visible final-state particles rather than a displaced vertex. The carrying objects are the dedicated trigger and reconstruction strategies - reclustered large-radius jets used as dark pion candidates, same-sign dileptons plus jets for boosted heavy neutral lepton decays, scouting triggers that retain only partial event information and reach muon transverse momenta as low as 4 GeV, and multivariate discriminants for background separation. Limits are derived from fits to reconstructed mass or missing transverse momentum distributions and quoted at 95% CL. These strategies, distributed across complementary final states, are what allow the searches to cover the mass and coupling ranges they claim.","core_discovery":"The central claim, stated in the abstract and summary, is that the eight analyses cited as Refs. [9-16] rule out previously unexcluded masses and couplings with the 140 $fb^{-1}$ Run 2 dataset. ATLAS excludes dark pion masses up to 940 GeV in a stealth dark matter model for dark-pion-to-dark-rho mass ratios of 0.15-0.45, the first collider search for this model. CMS probes heavy neutral leptons with masses between 10 GeV and 1.5 TeV mixed with one neutrino generation, including the first exclusion of exclusive tau-neutrino couplings above the W boson mass, and excludes Z' bosons decaying to HNL pairs for Z' masses from 0.4 to 4.6 TeV. Simplified dark matter models with an s-channel mediator are constrained through top-quark pair plus missing transverse momentum, four-top, mono-photon, and dijet resonance channels, and a dark Higgs model is excluded for dark matter masses of 100-300 GeV with mediator masses up to 2.5 TeV. A 2HDM with a pseudoscalar mediator is constrained by a three-channel combination, the CMS scouting analysis excludes dimuon resonances with masses in 1.1-2.6 and 4.2-7.9 GeV and sets dark photon mixing limits, and ATLAS excludes SM Higgs branching fractions above 1.3% for decays to a photon plus a massless dark photon, with heavy Higgs limits up to 3 TeV.","pith_inferences":["The paper's success with scouting at muon $p_T$ of 4 GeV suggests a natural extension it does not discuss: applying the same low-threshold trigger to electron pairs or dijets could close analogous low-mass windows for other dark-sector mediators.","Because only prompt decays are considered, sufficiently small couplings would make the same models evade these limits by becoming long-lived; a combined prompt-plus-displaced reinterpretation of the eight analyses would give the true Run 2 coverage, a step the review takes only for heavy neutral leptons.","If the exclusions hold, dark-sector model builders should shift benchmarks toward heavier masses or smaller couplings; in particular, the 0.4-4.6 TeV excluded $Z'$ range pushes left-right symmetric HNL scenarios toward the multi-TeV scale.","The 13.6 TeV Run 3 dataset, already larger than Run 2, will extend these limits statistically, but the largest discovery potential may come from reinterpreting the same final states in additional simplified models rather than from the energy increase alone."],"forward_implications":["Dark pion masses up to 940 GeV are excluded for the considered mass ratios, so the stealth dark matter model survives only at higher masses or smaller couplings.","Heavy neutral leptons with exclusive tau-neutrino mixing and masses above the W boson are probed for the first time, complementing lower-mass displaced-vertex searches.","The scouting-based dimuon search closes a low-mass window for dark photons, excluding narrow resonances in the 1.1-2.6 GeV and 4.2-7.9 GeV ranges that standard triggers cannot reach.","SM Higgs decays into a photon and a massless dark photon are limited to branching fractions below 1.3%, and heavy Higgs production in that decay channel is excluded for masses up to 3 TeV.","The combined Run 2 programme, not any single analysis, defines the new excluded region; the paper shows this explicitly for heavy neutral leptons by comparing prompt, displaced, and vector-boson-fusion channels."],"supporting_citations":[{"why":"ATLAS search for dark mesons decaying to top and bottom quarks; supplies the dark pion exclusion up to 940 GeV.","marker":"[9]"},{"why":"CMS search for heavy neutral leptons in trilepton final states; supplies the mass-mixing limits including the first tau-neutrino coupling exclusion above the W mass.","marker":"[10]"},{"why":"CMS search for Z' bosons decaying to heavy Majorana neutrino pairs; supplies the left-right symmetry model limits for Z' masses 0.4-4.6 TeV.","marker":"[11]"},{"why":"ATLAS constraints on dark matter with an s-channel mediator; supplies limits from top-pair plus missing momentum, four-top, mono-photon, and dijet resonance channels.","marker":"[12]"},{"why":"CMS search for dark matter with W+W- and transverse momentum imbalance in a dark Higgs model; supplies the DM, mediator, and dark Higgs mass exclusions.","marker":"[13]"},{"why":"ATLAS combination of dark matter searches in a 2HDM with a pseudoscalar mediator; supplies the combined exclusions from three search channels.","marker":"[14]"},{"why":"CMS search for low-mass dimuon resonances with scouting triggers; supplies the dark photon limits in the 1.1-2.6 and 4.2-7.9 GeV mass ranges.","marker":"[15]"},{"why":"ATLAS combination of searches for Higgs boson decays into a photon and a massless dark photon; supplies the 1.3% branching fraction exclusion and heavy Higgs limits.","marker":"[16]"}],"fun_headline_variants":["LHC's 140/fb dataset rules out new dark sector masses","Eight LHC searches shrink dark sector parameter space","First collider bounds on stealth dark matter from ATLAS","CMS excludes tau-neutrino couplings above W mass","ATLAS and CMS tighten limits on dark photons, neutrinos"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The whole summary rests on the eight underlying ATLAS and CMS analyses being correct in their background estimates, systematic uncertainties, and statistical procedures; this paper reports those results and does not independently verify them.","fun_headline_variants_meta":{"raw":{"variants":["LHC's 140/fb dataset rules out new dark sector masses","Eight LHC searches shrink dark sector parameter space","First collider bounds on stealth dark matter from ATLAS","CMS excludes tau-neutrino couplings above W mass","ATLAS and CMS tighten limits on dark photons, neutrinos"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.00028,"raw_usage":{"total_tokens":1669,"prompt_tokens":960,"completion_tokens":709,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":576,"completion_tokens_details":{"reasoning_tokens":627}},"tokens_in":576,"tokens_out":709,"duration_ms":7286,"temperature":1.0,"reasoning_tokens":627,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-11T19:47:03.611930+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"If any one of the eight analyses were re-run with a corrected background model that moved its 95% CL upper limit above the boundary the paper shows as excluded, the claim of extended coverage would be wrong for that model. A concrete place to look is the CMS scouting dimuon search: a narrow resonance with local significance above 5 $\\sigma$ anywhere between 1.1 and 7.9 GeV in the same 140 $fb^{-1}$ data would contradict the dark photon exclusion presented in Fig. 4.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"ATLAS search for dark mesons decaying to top and bottom quarks; supplies the dark pion exclusion up to 940 GeV."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"CMS search for heavy neutral leptons in trilepton final states; supplies the mass-mixing limits including the first tau-neutrino coupling exclusion above the W mass."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"CMS search for Z' bosons decaying to heavy Majorana neutrino pairs; supplies the left-right symmetry model limits for Z' masses 0.4-4.6 TeV."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"ATLAS constraints on dark matter with an s-channel mediator; supplies limits from top-pair plus missing momentum, four-top, mono-photon, and dijet resonance channels."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"CMS search for dark matter with W+W- and transverse momentum imbalance in a dark Higgs model; supplies the DM, mediator, and dark Higgs mass exclusions."},{"cited_title":"Bull.69(2024) 3005","cited_arxiv_id":null,"evidence_quote":"ATLAS combination of dark matter searches in a 2HDM with a pseudoscalar mediator; supplies the combined exclusions from three search channels."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"CMS search for low-mass dimuon resonances with scouting triggers; supplies the dark photon limits in the 1.1-2.6 and 4.2-7.9 GeV mass ranges."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"ATLAS combination of searches for Higgs boson decays into a photon and a massless dark photon; supplies the 1.3% branching fraction exclusion and heavy Higgs limits."}],"review_version":1}