{"id":"dbab8f6e-ddfc-445b-b91e-cefcde45ccb4","arxiv_id":"2508.08478","paper_version":1,"verdict":"CONDITIONAL","confidence":"LOW","novelty_score":4.0,"correctness_risk":"unknown","formal_verification":"none","parameter_count":2,"one_line_summary":"On IceTop simulations, a two-component lateral distribution fit recovers the GeV-muon content of air showers, and the reconstructed muon parameters shift with the chosen hadronic interaction model.","lead":"This paper tests whether IceTop, the surface array of the IceCube Neutrino Observatory, can separate the electromagnetic and low-energy muon parts of cosmic-ray air showers by fitting two different lateral distribution shapes at once, using simulations. The result matters because a trustworthy muon readout would sharpen cosmic-ray composition and hadron-physics measurements at PeV energies, but the reconstructed muon parameters are shown to depend on the assumed hadronic mode","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Muon-LDF accuracy claim depends on showing the muonic template is identifiable and the ground truth is not generated by the same fit family; the corrupted text leaves both unverified.","rationale":"The reader's weakest assumption already points at per-event template identifiability; I agree, with one sharpening. My concern is the possible circularity of the validation: if the same LDF family is used to generate the ground truth and to fit the data, 'accurate recreation' is not independently demonstrated. This is not an ad hominem or a disagreement with field consensus; it is a standard closure requirement for any decomposition method. The corrupted full text means the relevant definitions and fit constraints cannot be verified, which is why the reader's CONDITIONAL verdict is the right one. I would not move the verdict; I would attach the proposed particle-level-truth and injection tests as conditions for acceptance, and I would flag the missing evidence in the revision request. The hadronic-model comparison, while interesting, inherits the same identifiability risk, so it should not be interpreted as a physics result until the closure tests pass.","tokens_in":23460,"tokens_out":5301,"duration_ms":67492,"concrete_test":"Regenerate a test set with two independent truth definitions for the same simulated events: (a) the LDF parameters used in the simulation/generator, and (b) binned muon lateral density computed directly from tagged muon energy deposits or particle-level hits without any LDF fit. Refit all tank signals with the two-component LDF. The claim is supported only if reconstruction agrees with (b) to the quoted accuracy, while still showing the claimed hadronic-model spread. As a direct identifiability check, inject synthetic tank signals whose muonic LDF slope is shifted by ±20% from the reconstruction template and verify the fit recovers the injected slope rather than snapping to the template. This settles whether the muon component is seen in the data or imposed by the prior.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim is that the two-component LDF reconstruction recreates the muon distribution accurately. The load-bearing condition is not simply that the two templates have different shapes; it is that the simulated 'true' muon LDF used for validation is independent of the LDF functional form used in the fit. If the truth is produced by the same generator-level LDF parameterization that the fit inverts, the agreement is partly a template-prior recovery rather than evidence that the GeV muon component is identifiable in IceTop tank signals. That concern is sharpened by the physical regime: the muonic contribution is a small fraction of the EM-dominated signal at IceTop spacings, so an unconstrained two-template fit can trade normalization and slope between components without much change in the total. The submitted full text is mostly unreadable replacement characters, so sections defining the truth (particle-level vs. LDF-generated) and the fit constraints cannot be checked. This is load-bearing because it affects the accuracy demonstration itself and also the hadronic-model comparison: if the fit follows its template prior, the reported model spread may reflect the templates rather than the interaction models.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript presents a simulation-based study of IceTop air-shower reconstruction, in which electromagnetic and muonic lateral distribution functions (LDFs) are fitted simultaneously to tank signals on an event-by-event basis. The abstract claims that this two-component reconstruction accurately reproduces the muon distribution and that the reconstructed muonic LDF parameters vary significantly with the hadronic interaction model. However, the submitted full text is almost entirely unreadable, consisting of replacement characters with only the abstract and scattered equation fragments legible. No quantitative validation, no concrete definition of the LDFs or fit constraints, and no description of the simulation truth can be verified from the supplied material.","tokens_in":23600,"tokens_out":4060,"duration_ms":51090,"significance":"If the method and validation were fully supported, this work could be valuable for IceCube/IceTop cosmic-ray composition studies and for quantifying hadronic-model systematic uncertainties in surface-detector muon measurements. The paper does not ship machine-checked proofs, reproducible code, or a publicly accessible derivation; the contribution is currently unsubstantiated because the readable portion contains no quantitative accuracy metric, no uncertainty analysis, and no independent cross-check of the muon reconstruction.","major_comments":[{"comment":"The central claim that the two-component LDF reconstruction 'recreates the muon distribution in IceTop accurately' is not supported by any quantitative metric in the readable text. The manuscript must provide, at minimum, reconstructed-versus-true muon densities, bias and resolution as a function of energy and distance, and uncertainties on the reconstructed LDF parameters. Without these, the accuracy claim is unverifiable and load-bearing.","section":"Abstract / Full Text"},{"comment":"The submitted full text is corrupted and unreadable; sections, equations, figures, and tables cannot be inspected. This makes it impossible to check the definitions of the electromagnetic and muonic LDF templates, the exact fitting procedure, the constraints used, or the nature of the simulation truth. A clean, readable manuscript is required before any substantive evaluation can proceed.","section":"Full Text (unreadable)"},{"comment":"The stress-test concern about circularity is not resolved. If the 'true' muon LDF used for validation is generated from the same functional family and with the same parameterization as the muonic template fitted to the tank signals, then a good fit may only show template-prior recovery rather than genuine identifiability of the GeV muon component. The authors must demonstrate that the ground-truth muon distribution comes from an independent source, e.g., particle-level simulation output or a distinctly parameterized LDF, and that this independence is maintained in the closure tests.","section":"Validation / ground truth"},{"comment":"The physical regime makes identifiability nontrivial: the muonic signal is a small fraction of the electromagnetic signal at IceTop spacings, and an unconstrained two-template fit can trade normalization and slope between the components. The paper needs explicit identifiability checks, such as profile-likelihood scans, covariance analysis, or closure tests with injected muon components whose LDF shape differs from the template family. Without this, the reported shift of muonic parameters with hadronic model may reflect template degeneracy rather than a physical hadronic-model dependence.","section":"Identifiability of the two-component fit"}],"minor_comments":[{"comment":"No readable references are present in the submitted text, so the relationship to previous IceTop muon-reconstruction and LDF-fitting work cannot be assessed. The authors should ensure the bibliography is complete and properly rendered.","section":"References / context"},{"comment":"The figure and table captions appear garbled, making it impossible to interpret even the fragments that are visible. All figures and tables must be legible and properly captioned in the revised version.","section":"Figures and tables"}],"recommendation":"uncertain","confidential_remarks":"The submission is not in a reviewable state due to the corrupted full text. I recommend asking the authors to resubmit a clean, readable version before technical review proceeds. Once readable, the reviewer should focus on (i) quantitative validation metrics, (ii) independence of the simulation truth from the fitted LDF family, and (iii) identifiability of the muonic component at IceTop spacings."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Colleague,\n\nQuick take on 2508.08478. The abstract claims two things: the two-component LDF reconstruction recreates the muon distribution accurately in IceTop simulations, and the reconstructed muonic LDF parameters shift significantly with the hadronic interaction model. Both are plausible and standard for the field, but the submitted full text is encoding-corrupted to the point of unreadability, so the load-bearing details cannot be checked.\n\nWhat's actually new: not much on the abstract's own terms. The reconstruction scheme is described as the existing event-by-event approach; the paper is a validation and a hadronic-model systematic scan. That is still useful. IceTop is the only large surface array at the South Pole, and a quantified model spread on the reconstructed muon component would help composition and muon-deficit analyses.\n\nWhat I can't verify: the quantitative accuracy claim. The abstract gives no numbers, no comparison of reconstructed vs. true muon densities, no error bars. The stress-test concern is legitimate and directly on point: if the simulated 'true' muon LDF is generated with the same functional family the fit uses, the agreement partly reflects template-prior recovery, not identifiability in the tank signals. The muonic signal is a small fraction of the EM-dominated signal at IceTop spacings, so an unconstrained two-template fit can trade normalization and slope. That doesn't mean the paper is wrong; it means the referee needs to see the definition of the simulation truth, the fit constraints, and the separability checks. The corrupted text hides exactly that.\n\nThe hadronic-model scan is a mild circularity: if the fit follows its template prior, the model spread may reflect the templates. But even then, a quantified shift across generators is a useful systematic envelope, provided the shift is presented with uncertainties. Also, the corrupted source contains an embedded arXiv header from a different paper (2508.08479 cs.DC), which suggests the wrong file was submitted.\n\nBottom line: this is a workmanlike validation study, not a new discovery. It deserves a full peer review because IceTop muon reconstruction is central to current composition work, and the paper could supply the missing systematic. My verdict is conditional on the referee being able to read the full text. Tell the authors to resubmit a clean PDF.\n\nI would not cite it until the details are visible, but I'd send it to an expert referee.","headline":"Simulation validation of IceTop's two-component LDF reconstruction; plausible but unverifiable from the corrupted full text, and the accuracy claim depends on template identifiability and truth being independent of the fit family.","tokens_in":24165,"tokens_out":4042,"would_cite":false,"duration_ms":42132,"reading_group":"maybe","serious_thinker":"unclear","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"The paper establishes that the two-component LDF reconstruction reproduces the muon distribution in IceTop simulations, and that the reconstructed muonic LDF parameters shift significantly with the hadronic interaction model.","keywords":["air showers","muon lateral distribution function","IceTop","hadronic interaction models","cosmic-ray composition","electromagnetic component","detector simulation"],"falsifier":"Using simulations with Monte Carlo truth for the muon contribution in each tank, systematically reduce the muon signal and refit; if the reconstructed muonic LDF normalization fails to track the true muon fraction, or if removing the muon component leaves the muonic fit parameters essentially unchanged, the claimed accuracy of the two-component reconstruction is not established.","tokens_in":23258,"feed_emoji":"🧊","tokens_out":5671,"duration_ms":66075,"temperature":0.7,"pith_summary":"The paper asks whether a surface detector array like IceTop can see the muon part of an air shower separately from the overwhelming electromagnetic part. It argues yes: by fitting two lateral distribution functions at once—one for each component—the muon distribution can be recreated in simulated showers. It then shows the reconstructed muon parameters are not fixed by the data alone; they move noticeably with the hadronic interaction model assumed in the simulation. That matters because muon measurements are a primary window into cosmic-ray composition and hadronic physics, and any model dependence must be carried as a systematic if these reconstructed parameters are used as observables.","feed_headline":"Two-component fit recovers muon signal in simulated IceTop showers","feed_subtitle":"Reconstructed muon LDF parameters shift strongly with hadronic model, so composition analyses must carry that spread.","key_machinery":"The lateral distribution function (LDF)—the expected signal density in a tank as a function of perpendicular distance from the shower axis—is the central object. The reconstruction fits two LDFs at once to the same set of tank signals: one for the electromagnetic component and one for the muonic component. The argument rests on these two templates being distinguishable in the summed signal, so the fit can assign each tank's signal to the correct component; the muonic LDF parameters are then read off from the fitted template.","core_discovery":"The central claim is that a simultaneous fit of separate electromagnetic and muonic lateral distribution functions to IceTop tank signals can accurately recreate the muon distribution of an air shower as seen by the array. This is established in simulation: showers are generated, tank signals are simulated, and the two-template fit is shown to recover the muon component. The paper then shows that the parameters of the reconstructed muonic LDF—its normalization and shape—change substantially when different hadronic interaction models are used to generate the same observable conditions, so the model choice is a real source of systematic uncertainty in the reconstructed muon component.","pith_inferences":["An implication the paper leaves implicit: applied to data, the same two-component fit would let IceTop alone tag the muon content of individual showers, but only if the detector simulation's absolute signal scale matches data; a dedicated data/MC calibration would be needed.","The spread in reconstructed parameters across hadronic models is itself a handle: at energies where IceTop is sensitive, the measured muonic LDF could be compared with each model's prediction to discriminate between hadronic models.","Because the two LDF templates are fitted simultaneously, strong event-by-event shower fluctuations could push the fit into a degeneracy band; a useful stress test would be fitting with one template removed and checking how much the reconstructed electromagnetic result moves."],"forward_implications":["If the two-component reconstruction is accurate, IceTop can supply per-event muon lateral distributions at GeV energies without requiring in-ice muon measurements.","Any composition or hadronic-physics result derived from the reconstructed muonic LDF must attach a systematic uncertainty reflecting the observed across-model spread of the muonic LDF parameters.","The electromagnetic LDF reconstructed in the same fit should be correspondingly cleaner for studies of the electromagnetic shower size.","Muonic LDF parameters and their model spread can be used as inputs to combined IceTop–IceCube analyses, where high-energy muons measured in the deep detector anchor the GeV muon component."],"supporting_citations":[],"fun_headline_variants":["IceTop fit recovers muon signal, but hadronic model shifts it","Two-component LDF fit recovers muons, but model choice alters parameters","Hadronic model choice shifts IceTop's reconstructed muon parameters","Simultaneous EM and muon LDF fit recovers muons, but model matters"],"cache_read_input_tokens":2816,"weakest_assumption_plain":"The two component templates are identifiable in each shower: the muon signal is large enough, and its lateral shape different enough from the electromagnetic shape at the fitted distances, that the simultaneous fit returns the true muon component rather than a trade-off between the templates.","fun_headline_variants_meta":{"raw":{"variants":["IceTop fit recovers muon signal, but hadronic model shifts it","Two-component LDF fit recovers muons, but model choice alters parameters","Hadronic model choice shifts IceTop's reconstructed muon parameters","Simultaneous EM and muon LDF fit recovers muons, but model matters"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000553,"raw_usage":{"total_tokens":2420,"prompt_tokens":642,"completion_tokens":1778,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":386,"completion_tokens_details":{"reasoning_tokens":1695}},"tokens_in":386,"tokens_out":1778,"duration_ms":15997,"temperature":1.0,"reasoning_tokens":1695,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-05T21:32:50.078860+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Using simulations with Monte Carlo truth for the muon contribution in each tank, systematically reduce the muon signal and refit; if the reconstructed muonic LDF normalization fails to track the true muon fraction, or if removing the muon component leaves the muonic fit parameters essentially unchanged, the claimed accuracy of the two-component reconstruction is not established.","supporting_citations":[],"review_version":1}