{"id":"6cf37a4f-2126-4076-9d0c-2cb455cb453d","arxiv_id":"2601.12422","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":5,"one_line_summary":"A 3D air-shower simulation framework with ad-hoc modified hadronic interactions is validated against 1D CONEX and full CORSIKA, with important 3D lateral effects demonstrated.","lead":"This paper validates a new way to run 3D simulations of ultra-high-energy cosmic-ray air showers with artificially modified hadronic interactions, extending earlier 1D tools. The result is a validated infrastructure for testing whether changes to cross-section, elasticity, or multiplicity can explain the observed muon excess.","discovery_kind":"new_method","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Resampling correctness is assumed, not validated: Sec. III D only checks port fidelity between CONEX and CONEX 3D.","rationale":"The reader's weakest_assumption identifies the same load-bearing concern: the validation of modified interactions compares CONEX and CONEX 3D, which share the resampling code, so it only validates the port, not the physical faithfulness of the modifications. I agree. The central claim of maturity for physics conclusions requires that the ad-hoc modifications correspond to the intended changes in cross section, elasticity, and multiplicity. Without an independent test of the resampling algorithm, an undetected systematic error would invalidate any physics conclusions drawn. The reader's verdict is CONDITIONAL, which is appropriate: the implementation should be accepted only after an independent check or release of the code. My concern reinforces this conditionality but does not move the verdict to a different category. The proposed unit test is concrete, feasible, and directly settles whether the resampling is faithful.","tokens_in":16582,"tokens_out":9691,"duration_ms":103643,"concrete_test":"Build a unit test that applies the resampling algorithm to a large sample (≥10^5) of Sibyll2.3d-generated proton-proton interactions at a fixed lab energy (e.g., 10^16 eV). For each modified quantity, verify that the resampled sample reproduces the target f(E) within statistical uncertainty: for elasticity f_ela=1.5, the mean elasticity should rise by 50%; for multiplicity f_mult=1.7, the average charged multiplicity should increase by 70%. Also check total energy conservation in every resampled event. If the resampled moments deviate systematically from the targets, the modifications are not faithful and the framework is not mature for physics conclusions.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim that the modified-interaction implementation is 'mature enough for physics conclusions' rests on the correctness of the resampling algorithm for elasticity and multiplicity. Section III D compares CONEX and CONEX 3D under modifications, but both frameworks use the same resampling code ported from [9] (Section II). Agreement between them therefore demonstrates only that the 3D port is faithful, not that the resampling physically implements the intended changes. The paper relies on the original code being 'extensively tested' without providing an independent check. If the resampling contains a systematic bias—e.g., incorrect energy conservation when scaling elasticity, or an unintended correlation in multiplicity—both simulations share it, and the validation cannot reveal it. Consequently, physics conclusions drawn from the modified 3D showers would inherit any such error, and the central claim is not fully supported by the presented evidence.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper presents a method for implementing ad-hoc modifications of hadronic interaction parameters (cross section, elasticity, multiplicity) in CONEX 3D, a fully three-dimensional air-shower simulation framework that interfaces CONEX with CORSIKA. The modifications follow a logarithmic interpolation above a threshold energy E_thr, with independent thresholds and magnitudes for each parameter. The paper extensively validates the framework by comparing longitudinal and lateral observables, means and fluctuations, against CONEX and CORSIKA for proton and iron primaries at 5 EeV, using large statistics (7,000 showers per 3D setup; 100,000 for 1D). It then compares longitudinal profiles between CONEX and CONEX 3D under individual modifications, demonstrates the value of 3D information for muon lateral distributions, and tests the commutativity and additivity of parallel modifications. The central claim is that the implementation is 'mature enough for physics conclusions' provided the identified limitations in high-energy muon fluctuations are respected.","tokens_in":16882,"tokens_out":6473,"duration_ms":67751,"significance":"If the result holds, this work provides the cosmic-ray community with a tested 3D simulation tool for studying modified hadronic interactions, enabling physically meaningful comparisons with sparse ground-array data and multi-parameter interaction scenarios. The paper's strengths include unusually thorough validation statistics, open data availability, validation of the unmodified framework against independent CORSIKA simulations, and explicit acknowledgment of the limitations in muon fluctuations. The main residual risk is that the modified-interaction validation relies entirely on a consistency check with the 1D CONEX implementation, which shares the same resampling code, and the quantitative modified-interaction check is only presented for proton primaries.","major_comments":[{"comment":"The quantitative reproducibility check of the modifications is shown only for primary protons; the equivalent comparison for iron nuclei is absent. This is particularly relevant because Section II states that the nuclear cross-section modification uses a different parameterization than the original CONEX implementation. Without an iron benchmark, the central claim that the modified implementation is 'mature enough for physics conclusions' is not fully supported for nuclear primaries, which are part of the intended composition range. Please either add the missing iron comparison or explicitly restrict the claim to proton primaries.","section":"III D, Figs. 12-13"},{"comment":"The modified-interaction consistency check compares CONEX and CONEX 3D, but both frameworks use the same resampling code ported from [9]. Agreement therefore establishes that the 3D port is faithful, but it does not independently validate that the resampling physically realizes the intended modifications (e.g., energy conservation when scaling elasticity, correct leading-particle exclusion, target f19 distributions). Since the conclusion asserts maturity for physics conclusions, the authors should either add unit-level validation of the resampling against analytical or independent Monte Carlo expectations, or explicitly qualify the conclusion as consistency with the existing 1D implementation rather than absolute physical correctness.","section":"III D and VI"}],"minor_comments":[{"comment":"The text identifies Fig. 10 as the proton case and Fig. 11 as the iron case, but both figure captions state 'for primary iron nuclei.' The captions appear to be swapped; please correct this to avoid ambiguity.","section":"III C, Fig. 10 and Fig. 11 captions"},{"comment":"The notation 'Conex', 'CONEX', and 'Conex 3D' is used inconsistently; please standardize the capitalization and formatting of the framework names.","section":"Throughout"},{"comment":"The column descriptions in the caption are unclear: 'The fourth and sixth columns express the values in units of the statistical uncertainty' — specify which columns are meant (e.g., third and fifth) and define the statistical uncertainty used (standard error of the mean?).","section":"V, Table II"},{"comment":"The 'kink around 1300 g/cm2' attributed to the forced handover of particles to CORSIKA is given only a qualitative explanation. A brief quantitative description of the handover condition would strengthen the interpretation.","section":"III B"}],"recommendation":"major_revision","confidential_remarks":"The paper is a thorough technical validation and the open data are commendable. The main concern is the shared-resampling-code validation, which limits the strength of the central claim, and the absence of a quantitative modified-interaction check for iron primaries. These are addressable within the manuscript's scope, so I recommend major revision rather than rejection."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"This paper does something useful and does it carefully: it ports the existing 1D resampling of hadronic interaction parameters into CONEX 3D, adds simultaneous modifications with independent energy thresholds, and runs a substantial validation campaign. The statistics are serious — 7000 showers per 3D setup, 100k for 1D, with means and fluctuations compared against CORSIKA. The longitudinal agreement is excellent, and the lateral distributions under modified interactions are genuinely new. Showing that parallel modifications do not reduce to linear combinations of individual ones is a practical point the community will care about.\n\nThe honest limitations are also stated: high-energy muon fluctuations far from the core are not well reproduced, and the authors flag that the framework is mature enough only when that limitation is respected. The data are openly released, which I value.\n\nThe stress-test concern about shared resampling code is real but not as damaging as it sounds. Both CONEX and CONEX 3D use the same ported resampling, so the modified-interaction comparison in Sec. III D mostly demonstrates port fidelity, not independent physical validation. That is a fair limitation, but it is not a fatal one: the resampling algorithm is inherited from a previously published and extensively tested code, and the unmodified showers are independently checked against CORSIKA. The new part — the 3D structure — is validated independently. What is missing is an external check of the resampling physics itself, or release of the modified code so others can probe it. I would have liked a sentence quantifying how a hypothetical systematic bias in the resampling would propagate, but that is a request for extra analysis, not a reason to doubt the central result.\n\nThe paper is enabling infrastructure rather than a physics discovery. It will be useful to anyone simulating UHECR showers to interpret muon-excess and Xmax discrepancies, especially with sparse ground arrays. The writing is clear and the methodology is reproducible.\n\nMy recommendation: send it to peer review. Ask the authors to add a brief discussion of the resampling code's validation history and to either release the modified code or specify exactly what \"small adjustments\" were made. Neither is a blocker, but both would make the tool more trustworthy.\n\nI would bring this to a reading group, and I would cite it if I needed 3D modified-interaction simulations for my own work.","headline":"A thorough validation of CONEX 3D as a general tool for modified hadronic interactions; the shared-resampling caveat is real but minor, and the paper deserves serious refereeing.","tokens_in":17291,"tokens_out":1590,"would_cite":true,"duration_ms":19949,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"Ad-hoc modifications of hadronic interactions are now validated in full 3D air-shower simulations, enabling radial muon predictions for sparse ground arrays.","keywords":["cosmic rays","air showers","hadronic interactions","Monte Carlo simulation","CONEX 3D","muon production","shower maximum","lateral distribution"],"falsifier":"A direct comparison of modified 3D simulations against an independent implementation, e.g., native modifications inside CORSIKA without the CONEX resampling, or against measured lateral distributions of muons above 5 GeV far from the core, where the framework's fluctuations are known to deviate by more than 10%; if the deviations also appear in the mean or in a broader energy range, the central claim would be weakened.","tokens_in":16529,"feed_emoji":"⚛️","tokens_out":6181,"duration_ms":60654,"temperature":0.7,"pith_summary":"This paper establishes that ad-hoc modifications to three hadronic interaction parameters—cross section, elasticity, and multiplicity—can be faithfully implemented in full three-dimensional simulations of ultra-high-energy cosmic-ray air showers, not just in the one-dimensional longitudinal treatments used before. The authors validate the 3D framework against existing 1D simulations and against full 3D reference simulations, showing agreement within about 10% for most observables, with the exception of high-energy muon fluctuations far from the shower axis. They demonstrate that the 3D information matters: the total muon number, the quantity available to 1D simulations, masks a strong radial-dependent anti-correlation between muon yield and shower-maximum depth. They also show that modifying several parameters in parallel is not equivalent to adding their individual effects, so joint parameter scans are necessary for precision predictions. The claim is that the implementation is mature enough for physics conclusions, provided the muon-fluctuation limitation is respected.","feed_headline":"Full 3D air showers now accept modified hadron physics","feed_subtitle":"Validated against 1D and reference 3D codes; enables radial muon predictions for sparse detector arrays.","key_machinery":"The key machinery is the resampling algorithm that modifies secondary particles in each hadronic interaction to reach target elasticity and multiplicity values, combined with a pre-interaction scaling of the cross section, and the energy-dependent modification factor f(E)=1+(f_19-1)*log10(E/E_thr)/log10(10 EeV/E_thr) that determines the magnitude of each modification as a function of energy. This algorithm was ported from the 1D CONEX code into the CONEX 3D hybrid mode inside CORSIKA, where after a configurable threshold the full 3D shower is tracked. The port enables independent threshold energies and simultaneous modifications of several parameters, which was not previously possible.","core_discovery":"The central discovery is a validated method for applying resampling-based modifications of hadronic interactions—scaling the cross section, the elasticity (energy fraction of the leading particle), and the multiplicity (number of secondaries) by energy-dependent factors—within the CONEX 3D hybrid simulation option of CORSIKA. The modification factor grows logarithmically with energy above a threshold E_thr, reaching a chosen value f_19 at 10 EeV. The authors port the resampling code from the 1D CONEX package, extend it to allow independent thresholds and simultaneous modification of multiple parameters, and validate the result against 1D CONEX and pure CORSIKA simulations for proton and iron","pith_inferences":["The framework opens a path to treating ad-hoc parameter modifications as a surrogate model: a dense library of modified 3D simulations could be interpolated to scan the hadronic parameter space against experimental data, effectively converting the ad-hoc approach into a data-driven constraint on interaction models.","The identified weakness in high-energy muon fluctuations far from the axis suggests that the hybrid handover point or the cascade-equation treatment of very forward muon production may need refinement; a targeted fix could remove the main limitation for ground-array comparisons.","Because the modification factor is defined per nucleon for nuclear primaries, the effects are diluted for heavy nuclei; this energy-per-nucleon scaling implies that combined fits to composition and interaction modifications will need 3D simulations for each primary species, which is now feasible but computationally expensive.","The method could be extended to other parameters such as pion charge ratio or inelasticity, and the independent-threshold feature allows testing scenarios where the high-energy physics above 10^16 eV deviates from accelerator-based extrapolations."],"forward_implications":["Predictions for sparse ground arrays, which register particles at finite distances from the shower core, can now be computed directly under modified hadronic interactions, replacing an extrapolation from total muon numbers.","The observed muon excess and the deeper-than-expected shower maximum can be probed simultaneously in 3D, testing whether a single set of parameter modifications explains both discrepancies.","Parallel modifications of cross section, elasticity, and multiplicity yield predictions that differ from linearly combined individual effects at the percent level in muon number and up to 10 g/cm^2 in X_max, so joint scans are needed for precision comparisons.","The validation establishes that the hybrid CONEX 3D scheme is reliable even with a very low Monte-Carlo-to-cascade-equation threshold of 10^13 eV, extending the usable energy range for modified-interaction studies."],"fun_headline_variants":["Hadronic tweaks go 3D for cosmic ray showers","3D simulations unlock modified hadron interactions","Validated 3D method tests hadron parameter tweaks","Energy-dependent hadron mods now in full 3D showers"],"cache_read_input_tokens":2304,"weakest_assumption_plain":"The resampling code ported from CONEX is assumed correct; the validation only demonstrates that CONEX 3D reproduces the 1D code's results, so any error in the original algorithm would be inherited without detection.","fun_headline_variants_meta":{"raw":{"variants":["Hadronic tweaks go 3D for cosmic ray showers","3D simulations unlock modified hadron interactions","Validated 3D method tests hadron parameter tweaks","Energy-dependent hadron mods now in full 3D showers"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000581,"raw_usage":{"total_tokens":2538,"prompt_tokens":672,"completion_tokens":1866,"prompt_tokens_details":{"cached_tokens":256},"prompt_cache_hit_tokens":256,"prompt_cache_miss_tokens":416,"completion_tokens_details":{"reasoning_tokens":1807}},"tokens_in":416,"tokens_out":1866,"duration_ms":13485,"temperature":1.0,"reasoning_tokens":1807,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-03T09:47:18.211853+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A direct comparison of modified 3D simulations against an independent implementation, e.g., native modifications inside CORSIKA without the CONEX resampling, or against measured lateral distributions of muons above 5 GeV far from the core, where the framework's fluctuations are known to deviate by more than 10%; if the deviations also appear in the mean or in a broader energy range, the central claim would be weakened.","supporting_citations":[],"review_version":1}