{"id":"ea21c2e4-edbb-4df9-a3d9-e707da091fc8","arxiv_id":"2501.09796","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":1,"one_line_summary":"A model-independent catalog of branching-ratio limits for singly and doubly charged scalars from LEP and LHC Drell-Yan data, organized by weak isospin.","lead":"The authors convert existing LEP and LHC search limits into model-independent upper bounds on the decay fractions of singly and doubly charged scalar particles. The bounds depend only on the scalar's mass, electric charge, and weak isospin, so any new model can be tested without redoing the simulations.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Caveat on W-mediated production is the load-bearing assumption: model independence holds only if current DY-derived limits are insensitive to associated S++ S- production, which is asserted but not demonstrated.","rationale":"The paper's headline contribution is a model-independent recipe for converting DY pair-production limits into branching-ratio bounds, organized by (m, Q, t3). The calculation of the gamma/Z DY cross-section itself is credible: Eq. (2) follows from the covariant derivative, and the NLO QCD implementation with MG5 is standard. The concern is not about the algebra or the code but about the mapping from experimental limits to the DY-only production cross-section. The paper explicitly excludes W-mediated associated production in footnote 5 and asserts that current searches are weakly sensitive to it, but no numerical demonstration is provided. Since the same SM gauge structure that gives the Z/gamma coupling also gives W couplings whenever a charge-2 scalar has a charge-1 partner in the same multiplet, the model-independence claim is exactly as strong as that exclusivity assumption. If W-mediated production is subdominant in the signal regions used by ATLAS and the recast analyses, the central claim stands; if not, the bounds remain valid only as conservative limits and the advertised model independence is overstated. This is the same weakest assumption identified by the reader, so the verdict remains CONDITIONAL and no adjustment is needed.","tokens_in":14179,"tokens_out":14235,"duration_ms":178225,"concrete_test":"Use the full HTM or GM FeynRules/UFO implementation, including W-mediated couplings, to generate pp -> H++H-- and pp -> H++H- at 13 TeV for m_H++ = 200, 400, 600, 800 GeV with identical decay BRs, pass both samples through the ATLAS 139 fb-1 multi-lepton selection used to derive sigma95 in Ref. [9], and recompute the 95% CL BR limits. If the H++H- sample changes the excluded BR by more than 10% at any mass point, the W-mediated omission is numerically significant and the model-independence statement in the abstract and Eq. (4) needs a quantitative caveat; if the shift is negligible, the footnote's claim is confirmed.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The algebraic Z/gamma coupling in Eq. (2) is standard, so Eq. (2) is not the vulnerable premise by itself. The vulnerability is the implicit exclusivity assumption: the 95% CL limits sigma95 used in Eqs. (3)-(4) are attributed entirely to the s-channel gamma/Z DY amplitude. For scalar multiplets with |Delta Q|=1 partners (HTM, GM, LRSM, Zee-type), the same gauge sector also produces W-mediated associated final states, pp -> S_Q S_{Q-1}, e.g., pp -> H++ H-. Footnote 5 dismisses these because 'current searches have rather weak sensitivity,' but no cross-section or recast check is shown. If such associated production contributes to the ATLAS multi-lepton signal regions used in Figs. 2 and 5, then sigma95 is not a limit on sigma_prod(DY pair) alone, and the BR bound from Eq. (4) is not strictly model-independent; it is a conservative bound that depends on the extra parameters (total isospin, mixing angle, mass splitting) the paper says it avoids. This is the weakest link in the central claim.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper proposes a model-independent interpretation of LHC and LEP searches for pair-produced charged scalars. Starting from the observation that the Drell-Yan production cross section for a colorless charged scalar depends only on its mass, electric charge Q, and weak-isospin component t3, the authors use Eq. (4), BR ≤ sqrt(σ95/σprod), to convert existing 95% CL upper limits into upper bounds on branching ratios for singly and doubly charged scalars with various t3. They compute NLO QCD DY cross sections with FeynRules and MG5 aMC, apply the method to dilepton, WW, Wγ, WZ, τν, and long-lived searches, and validate against model-specific results for LRSM, GM, HTM, and LEP 2HDM. The paper also discusses mixed-t3 states and gives an HTM application. The central analytic relation is standard and the cross-checks against existing LEP and LRSM limits provide some confidence.","tokens_in":14461,"tokens_out":10976,"duration_ms":130305,"significance":"If the method is valid, it yields a useful catalog that lets experimental limits be reinterpreted for any scalar with given (m, Q, t3) without new simulations. The core relation Eq. (2) is parameter-free for fixed quantum numbers, and the reproduction of the known LEP 2HDM bound and the LRSM limits is a valuable sanity check. The paper is clearly written and addresses a practical need in the phenomenology community. The main caveat, discussed below, is whether the model-independence claim is fully supported given the neglect of W-mediated associated production.","major_comments":[{"comment":"Footnote 5 dismisses W-mediated associated production by saying that 'current searches have rather weak sensitivity,' but no quantitative evidence is supplied. For the models in Table 1 that contain both S++ and S+ (HTM, GM, LRSM, Zee-type), the process pp → S++S− can populate the same multi-lepton signal regions used in Figs. 2 and 5; if it does, σ95 in Eq. (3) is not a limit on σprod(DY) alone, and the bound from Eq. (4) is a conservative upper bound whose tightness depends on extra parameters that the paper claims to avoid. The authors should either provide a recast or cross-section estimate showing that W-mediated production is negligible in the actual signal regions, or explicitly state and prove that the derived bounds remain valid as conservative upper bounds in the presence of such processes. This is necessary to substantiate the paper's central model-independence claim.","section":"Methodology and results (footnote 5; Eqs. (3)-(4))"},{"comment":"The extension to mixed-t3 states is not reproducible as written. After the rotation in Eq. (5), the Z coupling to a physical state Sj+ is given by the jj element of U^T diag(K0, K1) U, so the DY cross section for Sj+Sj− depends on the mixing angle θ in a way that is not stated. The paper should provide the explicit coupling matrix and the formula used to generate Fig. 6; without this, the mixed-case claim is unsupported and the reader cannot reproduce the lower bounds shown there.","section":"Isospin dependent limits (Eq. (5) and Fig. 6)"}],"minor_comments":[{"comment":"The bullet 'In the case of the GM model, the H++5 decays to Wγ' violates charge conservation: a doubly charged scalar cannot decay to W+γ. This should read H+5 → W+γ, and the same typo appears in the next line of that bullet.","section":"Conclusions"},{"comment":"The phrase 'This approach enables to determine limits' is ungrammatical; it should be reworded as 'This approach enables one to determine limits' or 'This approach allows limits to be determined.'","section":"Abstract"},{"comment":"The details of the NLO cross-section calculation (PDF set, factorization and renormalization scales, and the numerical values of σprod) are not provided. A table or short appendix with these inputs would make the catalog reproducible.","section":"Methodology and results"},{"comment":"The long-lived doubly charged scalar bound from CDF is included in Fig. 5, but the text does not describe how the production cross-section at the 1.96 TeV p-pbar collider was computed. A brief explanation should be added.","section":"Isospin dependent limits (Fig. 5)"},{"comment":"The caption notes that lines joining discrete t3 values are 'drawn only for clear visual representation'; this is helpful, but it could be stated more prominently in the text to avoid any impression of continuous coverage.","section":"Fig. 5 caption"},{"comment":"Reference [11] is cited as an arXiv preprint without a journal reference; the authors should update it if it has appeared in a journal.","section":"References"}],"recommendation":"major_revision","confidential_remarks":"The paper's central idea is sound and the presentation is generally clear. The key technical risk is the unquantified neglect of W-mediated associated production, which bears directly on the model-independence claim. If the authors can demonstrate conservativeness or quantify the effect in the relevant signal regions, I would support publication. The absence of numerical cross-section values is also worth addressing in revision."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The genuinely new thing here is the systematic catalog: for singly and doubly charged scalars with t3 from -1 to +1, the authors take existing 95% CL cross-section limits and invert them into branching-ratio bounds using the fact that DY pair production depends only on mass, charge, and t3. That is a practical service for Run 3 and HL-LHC interpretation, and the paper does it cleanly. The NLO cross-sections are computed with MG5 aMC, the central formulas (3)-(4) are elementary and correctly applied, and the LEP validation (t3 = +1/2) matching the official 2HDM bound is a nice sanity check. The model survey in Table 1 is accurate and useful, and the mixed-angle example for the GM model is a good illustration.\n\nThe soft spots are real but not fatal. First, the W-mediated associated production caveat in footnote 5 is load-bearing for the model-independence claim. If a scalar multiplet has partners with |Delta Q| = 1, then pp -> S_Q S_{Q-1} can contribute to the same multi-lepton signal regions used for the ATLAS limits. The paper dismisses this by saying current searches have weak sensitivity, but no cross-section estimate or recast check is shown. That is the one place where the claimed model independence is asserted rather than demonstrated. It does not sink the paper — the derived bounds are still conservative if extra production only adds to the signal — but the abstract's phrase 'without appealing to a specific model' is too strong.\n\nSecond, the internal inconsistency in the conclusions (H++5 vs H+5, and 300 vs 320 GeV for the GM mass bound) should have been caught. The caption of Fig. 6 says the GM point sits around 300 GeV; the left panel of Fig. 5 says 320 GeV. That needs fixing. Third, the mixing-angle formula used in Fig. 6 is not given explicitly; the reader has to infer it. Fourth, using the 36 fb^-1 ATLAS dilepton limits instead of the 139 fb^-1 analysis is explained, but the justification (the newer analysis assumes a specific BR relation) is reasonable and stated.\n\nWho is this for? Phenomenologists who want a quick, model-agnostic way to turn charged-scalar search limits into BR constraints, and experimentalists doing reinterpretations. It deserves a serious referee: the method is sound, the physics is clear, and the flaws are fixable. I would not cite it in my own work before the inconsistencies are resolved, but I would send it to review.","headline":"A useful, mostly sound catalog that converts DY cross-section limits into isospin-dependent branching-ratio bounds; the model-independence claim is real but rests on a footnoted assumption about W-mediated production that the paper does not quantify.","tokens_in":14951,"tokens_out":911,"would_cite":false,"duration_ms":11441,"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 the Drell-Yan pair-production cross-section of charged scalars at the LHC depends only on mass, electric charge, and the third component of weak isospin, so existing limits can be converted into model-independent…","keywords":["charged scalars","Drell-Yan production","weak isospin","branching ratio bounds","LHC searches","doubly charged Higgs","Higgs triplet model","Georgi-Machacek model"],"falsifier":"Measure the Drell-Yan cross-section ratio, at fixed mass, for two charged scalars with the same charge but different $t_3$, for example $t_3=+1$ and $t_3=0$ doubly charged scalars in same-sign dilepton events; Eq. (2) predicts a specific ratio through the photon-$Z$ interference term, and a significant deviation would reveal an extra production mechanism. Alternatively, if a charged scalar with a $|\\Delta Q|=1$ partner is discovered, compute the $W$-mediated contribution and check whether the observed cross-section exceeds the photon/$Z$-only prediction by more than the quoted uncertainties.","tokens_in":14025,"feed_emoji":"⚛️","tokens_out":12107,"duration_ms":104261,"temperature":0.7,"pith_summary":"This paper argues that the Drell-Yan pair-production cross-section of a charged scalar at the LHC is fixed once the scalar's mass, electric charge $Q$, and third weak-isospin component $t_3^{(+Q)}$ are specified. If that is right, every $95\\%$ CL upper limit from LEP and LHC searches can be read directly as a bound on the scalar's branching ratio, with no need to simulate a particular model. The authors compile such bounds for singly and doubly charged scalars with $t_3$ values spanning $[-1,1]$ and $[0,1]$, covering same-sign dilepton, $W^+W^+$, $W^+\\gamma$, $W^+Z$, and $\\tau^+\\nu$ final states. They validate the recipe on the Higgs triplet and Georgi-Machacek models and show how it organizes limits for many other extended scalar sectors.","feed_headline":"Charged scalar limits collapse to mass, charge, isospin","feed_subtitle":"Same-sign dilepton and W-gamma searches can now bound any singly or doubly charged scalar, whatever the model.","key_machinery":"The load-bearing identity is Eq. (2), $K_Z^Q = t_3^{(+Q)} - Q \\sin^2\\theta_W$, the $Z$-boson coupling of the charged scalar in units of $e/(\\sin\\theta_W \\cos\\theta_W)$. This one number fixes the photon-$Z$ interference pattern and therefore the whole Drell-Yan cross-section at a given mass. The second piece is the reinterpretation formula Eq. (4), $\\mathrm{BR}(S_Q^+\\to F_1) \\le \\sqrt{\\sigma_{95}/\\sigma_{\\rm prod}}$, which converts measured cross-section limits into branching-ratio bounds. The production cross-sections are evaluated at next-to-leading order in QCD, and the paper treats the narrow-width case so that production and decay factorize.","core_discovery":"The central claim is that charged-scalar pair production through photon and $Z$ exchange is governed by a single coupling coefficient $K_Z^Q = t_3^{(+Q)} - Q \\sin^2\\theta_W$, so the production cross-section $\\sigma_{\\rm prod}(m, Q, t_3)$ carries no other model information. An experimental $95\\%$ CL bound $\\sigma_{95}$ on $pp \\to S_Q^+ S_Q^- \\to F_1 \\bar F_2$ therefore becomes the branching-ratio constraint $\\mathrm{BR}(S_Q^+\\to F_1)\\,\\mathrm{BR}(S_Q^-\\to \\bar F_2) \\le \\sigma_{95}/\\sigma_{\\rm prod}$, which reduces to $\\mathrm{BR}(S_Q^+\\to F_1) \\le \\sqrt{\\sigma_{95}/\\sigma_{\\rm prod}}$ when the two decay chains coincide. The same bound then applies to every model whose charged scalar occupies the same $(Q, t_3)$ slot: the doubly charged scalars of the Higgs triplet and Georgi-Machacek models share one constraint, and the right-handed doubly charged scalar of the left-right symmetric model and the Zee-Babu scalar share another. The paper works out these bounds for mass ranges currently probed at LEP and the LHC and demonstrates the translation onto model parameters in the Higgs triplet model.","pith_inferences":["Extending the same catalog to charges $Q \\ge 3$ would require no new formalism, only experimental searches in the corresponding final states; the coupling formula and reinterpretation identity are charge-agnostic.","The photon/$Z$-only assumption is the least secure piece at future luminosities: if $W$-mediated pair production becomes observable for models with $|\\Delta Q|=1$ partners, the bounds would need an additional parameter, the total isospin and mass splitting.","A direct experimental test of the whole classification is the cross-section ratio for $t_3=+1$ versus $t_3=0$ at fixed mass; measuring that ratio in same-sign dilepton events would probe Eq. (2) without any model assumption.","The branching-ratio bounds could be compiled as a lookup table for global fits, letting any proposed scalar model be checked against LHC data by table lookup rather than a dedicated simulation."],"forward_implications":["If correct, the same experimental limit applies to any model with a charged scalar in the same $(m, Q, t_3)$ slot: the Higgs-triplet and Georgi-Machacek doubly charged scalars ($t_3=1$) share a bound, and the left-right symmetric $H_R^{++}$ and Zee-Babu scalar ($t_3=0$) share another.","The $W^+\\gamma$ channel is identified as a central search target for singly charged scalars; the recast limits used here already exclude branching ratios above roughly 40% for a 300 GeV scalar.","In the Georgi-Machacek model, the $W^+W^+$ channel places a lower mass bound near 320 GeV on the doubly charged scalar, and the $W^+\\gamma$ channel bounds the singly charged scalar near 300 GeV.","Projected HL-LHC sensitivity in the same-sign dimuon channel could exclude doubly charged scalars with $t_3=1$ up to about 1.5 TeV if they decay predominantly to muons.","Even long-lived doubly charged scalars with no visible decay mode receive $t_3$-dependent mass bounds, here derived from Tevatron data, so the classification covers scenarios invisible to prompt searches."],"supporting_citations":[{"why":"Supplies the $K_Z^Q = t_3 - Q \\sin^2\\theta_W$ formula and the observation that the Drell-Yan cross-section depends only on $Q$, $t_3$ and mass.","marker":"[8]"},{"why":"Provides the LEP $e^+e^- \\to S^+S^-$ limits on $\\mathrm{BR}(S^+ \\to \\tau^+\\nu)$ that the paper generalizes to other $t_3$ values.","marker":"[7]"},{"why":"Provides the ATLAS 139 fb$^{-1}$ multi-lepton limits used for the same-sign dilepton branching-ratio bounds in the isospin comparison.","marker":"[9]"},{"why":"Provides the ATLAS limits on $pp \\to S^{++}S^{--} \\to W^+W^+$ used for the diboson constraints.","marker":"[10]"},{"why":"Recast analysis supplying the LHC bounds on singly charged scalars in the $W^+\\gamma$ and $W^+Z$ final states.","marker":"[12]"},{"why":"Provides the ATLAS 36 fb$^{-1}$ same-sign dilepton limits used in the main doubly charged scalar plots.","marker":"[59]"},{"why":"Derives the square-root reinterpretation formula $\\mathrm{BR} \\le \\sqrt{\\sigma_{95}/\\sigma_{\\rm prod}}$ for converting cross-section limits into branching-ratio bounds.","marker":"[50]"},{"why":"Supplies the NLO QCD correction for doubly charged Higgs pair production used in the production cross-section.","marker":"[55]"}],"fun_headline_variants":["Charged scalar limits: just mass, charge, and isospin","Drell-Yan bounds on charged scalars decoded by weak isospin","Model-free charged scalar constraints from Drell-Yan data","Weak isospin collapses charged scalar search space","One isospin coefficient sets all charged scalar limits"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The result depends on the assumed formula for the $Z$ coupling being the complete description of production, with $W$-mediated channels neglected; if a charged scalar receives sizable model-dependent production, the branching-ratio limits would no longer be strictly model-independent.","fun_headline_variants_meta":{"raw":{"variants":["Charged scalar limits: just mass, charge, and isospin","Drell-Yan bounds on charged scalars decoded by weak isospin","Model-free charged scalar constraints from Drell-Yan data","Weak isospin collapses charged scalar search space","One isospin coefficient sets all charged scalar limits"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000224,"raw_usage":{"total_tokens":1480,"prompt_tokens":981,"completion_tokens":499,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":597,"completion_tokens_details":{"reasoning_tokens":413}},"tokens_in":597,"tokens_out":499,"duration_ms":5128,"temperature":1.0,"reasoning_tokens":413,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-10T19:39:51.433925+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure the Drell-Yan cross-section ratio, at fixed mass, for two charged scalars with the same charge but different $t_3$, for example $t_3=+1$ and $t_3=0$ doubly charged scalars in same-sign dilepton events; Eq. (2) predicts a specific ratio through the photon-$Z$ interference term, and a significant deviation would reveal an extra production mechanism. Alternatively, if a charged scalar with a $|\\Delta Q|=1$ partner is discovered, compute the $W$-mediated contribution and check whether the observed cross-section exceeds the photon/$Z$-only prediction by more than the quoted uncertainties.","supporting_citations":[],"review_version":1}