A gauge-invariant measure for lattice chiral fermions

Nathaniel Craig

For SU(5) overlap fermions in the representation 10⊕5̄ on finite periodic four-dimensional Euclidean lattices, the paper constructs a smooth exponentially local measure current satisfying the anomaly equation and full integrability on admissible gauge fields. It reconstructs a gauge-invariant measure on every nonempty component, up to a constant phase, and restricts it to the four stated global forms of the Standard Model gauge group.

Sources for this record

What was already known

Lüscher’s abelian construction and perturbative nonabelian results did not give this stated nonperturbative smooth local measure for the covered chiral theories. Craig proposed the refinement strategy; the proof compares projectors at successive lattice spacings and controls the resulting current and global phases.

AI involvement AI-led

Craig explicitly describes the result as an Astra-led proof after his refinement proposal and iterations with Astra and outside experts. Astra also carried out proposed tests and formalization. Craig revised the text; Golterman, Shamir and other named experts contributed questions and feedback. The archive’s subsequent proof-detail completions remain separately documented.

Importance Major

Addresses a longstanding obstruction to a nonperturbative lattice definition of the covered chiral gauge theories.

Limitations

Admissibility is an essential plaquette bound. Relative phases between components remain free; reflection positivity, practical simulation and an interacting continuum theory remain open. The checking report records a failed original Comparator reference comparison alongside successful separate kernel and statement-type checks; physical correspondence is not experimental confirmation.

Technical verification Formal (Lean)

Craig’s versioned supplement reports successful Lean 4.35.0-rc2 compilation of all 16 modules, standard-axiom checking and separate kernel replay of the exported proofs, with statement-type checks. The original Comparator command failed on generated-name/proof-body matching; separate proof checks passed. Source correspondence was reviewed by AI agents, rather than an independent human panel.

Formal checking

Craig’s versioned supplement reports successful Lean 4.35.0-rc2 compilation of all 16 modules, standard-axiom checking and separate kernel replay of the exported proofs, with statement-type checks. The original Comparator command failed on generated-name/proof-body matching; separate proof checks passed. Source correspondence was reviewed by AI agents, rather than an independent human panel.

Checker
Lean 4.35.0-rc2 and separate kernel/axiom checks reported by Nathaniel Craig
Scope
Theorem 4.1: smooth exponentially local gauge-covariant current and gauge-invariant measure for SU(5), R=10⊕5-bar, on each nonempty admissible component of a finite periodic four-dimensional lattice; stated Standard Model restrictions.
Basis
Reported by the linked checker
Evidence source

Checking a formal statement does not establish that it matches the original problem.

Human understanding Few

Craig’s initial refinement strategy and expert feedback are documented. The reviewed sources do not identify how completely a named human can explain the Astra-led analytic and global-integrability proof; Few is the documentation default, not a report that humans cannot understand it.

Correction and publication history

2026-10-22 · publication

Added the sourced contribution with its stated hypotheses, AI role, prior work and checking limits.

Read this published revision