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arxiv: 1906.12310 · v1 · pith:4RPK55FCnew · submitted 2019-06-28 · ✦ hep-ph · hep-ex

Proposal for the validation of Monte Carlo implementations of the standard model effective field theory

Gauthier Durieux (ed.) , Ilaria Brivio (ed.) , Fabio Maltoni (ed. ex officio) , Michael Trott (ed. ex officio) , Simone Alioli , Andy Buckley , Mauro Chiesa , Jorge de Blas
show 33 more authors
Athanasios Dedes C\'eline Degrande Ansgar Denner Christoph Englert James Ferrando Benjamin Fuks Peter Galler Admir Greljo Valentin Hirschi Gino Isidori Wolfgang Kilian Frank Krauss Jean-Nicolas Lang Jonas Lindert Michelangelo Mangano David Marzocca Olivier Mattelaer Kentarou Mawatari Emanuele Mereghetti David J. Miller Ken Mimasu Michael Paraskevas Tilman Plehn Laura Reina Janusz Rosiek J\"urgen Reuter Jos\'e Santiago Kristaq Suxho Lampros Trifyllis Eleni Vryonidou Christopher White Cen Zhang Hantian Zhang
This is my paper

Pith reviewed 2026-05-25 13:30 UTC · model grok-4.3

classification ✦ hep-ph hep-ex
keywords SMEFTMonte Carlo validationeffective field theoryamplitude comparisontree-level validationcross-validationstandard model extensions
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The pith

Numerical comparisons of squared amplitudes at selected phase-space points can cross-validate Monte Carlo implementations of the standard model effective field theory.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper proposes a concrete procedure for checking that different computer programs correctly implement the standard model effective field theory in event generation. The method works by computing squared amplitudes for the linear effective-field-theory pieces and their interference with standard-model contributions, then comparing the numerical values between pairs of implementations at chosen momentum configurations and parameter values. Comparisons are carried out mainly at tree level, with a brief discussion of possible one-loop extensions. If the numbers agree, the implementations are considered mutually consistent for the processes examined. The paper also catalogues existing SMEFT Monte Carlo tools and the comparisons already performed with this approach.

Core claim

The central claim is that pairwise numerical comparison of the squares of linear SMEFT amplitudes and of their interference with the standard model, evaluated at specific phase-space and parameter points, constitutes a practical validation procedure for Monte Carlo implementations of the SMEFT.

What carries the argument

Numerical comparison of squared amplitudes at fixed phase-space and parameter points, performed separately on the linear EFT squares and on the SM-EFT interference terms.

If this is right

  • Tree-level SMEFT implementations in different Monte Carlo generators can be checked for mutual consistency on a process-by-process basis.
  • The same point-wise comparison technique can be applied to the interference terms between the effective theory and the standard model.
  • Existing SMEFT Monte Carlo codes can be systematically listed and cross-checked using the proposed benchmarks.
  • The validation procedure can be extended to one-loop order for selected processes.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Validated implementations could then be used interchangeably when generating simulated events for collider searches that include SMEFT effects.
  • Persistent numerical disagreement at the chosen points would flag an error in at least one of the codes.
  • The method supplies a practical route to reduce theoretical uncertainty when combining results from multiple simulation tools.

Load-bearing premise

Agreement on squared amplitudes at a finite collection of chosen points is sufficient to establish that two implementations agree everywhere in phase space and for all parameter values.

What would settle it

Two implementations agree at all the proposed validation points but produce numerically different results for an observable or process evaluated at a different phase-space or parameter point.

read the original abstract

We propose a procedure to cross-validate Monte Carlo implementations of the standard model effective field theory. It is based on the numerical comparison of squared amplitudes computed at specific phase-space and parameter points in pairs of implementations. Interactions are fully linearised in the effective field theory expansion. The squares of linear effective field theory amplitudes and their interference with standard-model contributions are compared separately. Such pairwise comparisons are primarily performed at tree level and a possible extension to the one-loop level is also briefly considered. We list the current standard model effective field theory implementations and the comparisons performed to date.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

0 major / 2 minor

Summary. The manuscript proposes a procedure to cross-validate Monte Carlo implementations of the standard model effective field theory (SMEFT). The method relies on numerical comparisons of squared amplitudes (and their interferences with the SM) evaluated at specific phase-space and parameter points between pairs of implementations. All interactions are linearised in the EFT expansion; the squares of the linear EFT amplitudes and the SM-EFT interference terms are compared separately. The primary focus is tree-level calculations, with a brief discussion of a possible one-loop extension. The paper also catalogs existing SMEFT implementations and the comparisons that have already been performed.

Significance. If adopted, the proposed validation procedure would provide a practical, community-wide standard for ensuring consistency among SMEFT Monte Carlo codes, which is essential for reliable EFT interpretations of LHC data. The explicit separation of linearised EFT contributions from interferences is a clear strength that reduces the risk of implementation errors. The manuscript usefully inventories current tools and prior checks, thereby lowering the barrier to future pairwise validations. No machine-checked proofs or public validation code are supplied, but the proposal itself constitutes a concrete, actionable contribution to the field.

minor comments (2)
  1. [Abstract / Section on one-loop extension] The abstract states that 'a possible extension to the one-loop level is also briefly considered.' If space permits, a short paragraph in the main text outlining the concrete obstacles (e.g., UV renormalisation or infrared subtraction) would help readers assess the feasibility of that extension.
  2. [Section cataloguing implementations] When listing existing SMEFT implementations, including the specific versions or git commits used in the comparisons already performed would improve reproducibility of the cited checks.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for their positive assessment of our manuscript and for recommending acceptance. The referee's summary correctly identifies the core proposal and its potential utility as a community standard for SMEFT Monte Carlo validation.

Circularity Check

0 steps flagged

No circularity: external validation proposal

full rationale

The paper proposes a practical numerical cross-validation procedure for SMEFT Monte Carlo implementations via pairwise comparison of squared amplitudes (and SM interference) at selected phase-space and parameter points, with linearisation in the EFT expansion. This is a methodological recommendation without any derivation chain, fitted parameters renamed as predictions, or load-bearing self-citations. The central claim does not reduce to its own inputs by construction and contains no self-definitional, ansatz-smuggling, or renaming steps. The finite-point nature of the checks is explicitly acknowledged as a feature of numerical validation rather than a hidden assumption.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The proposal relies on standard assumptions from quantum field theory and Monte Carlo simulation techniques without introducing new free parameters or entities.

axioms (2)
  • domain assumption Interactions are fully linearised in the effective field theory expansion.
    Explicitly stated as the basis for the comparisons in the proposal.
  • domain assumption Numerical agreement at selected points can detect implementation errors in Monte Carlo generators.
    This underpins the entire validation strategy.

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discussion (0)

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Forward citations

Cited by 1 Pith paper

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