Establish whether the migration nuisance is degenerate with nucleon final-state-interaction parameters

Determine whether the proton-visibility migration fraction is fully degenerate at the one-standard-deviation level with the GENIE nucleon mean-free-path, nucleon absorption, or charge-exchange final-state-interaction parameters when those nuisance directions are floated simultaneously.

Background

The paper tests the relationship between the effective migration fraction and the GENIE nucleon mean-free-path parameter only through fixed shifts of the latter, rather than by fitting both parameters simultaneously. This restriction is motivated by the low effective rank of the MicroBooNE covariance matrix.

The fixed-shift tests show only small changes in the fitted migration fraction over the tested range, but they do not rule out degeneracy when the parameters are jointly varied. The authors explicitly identify a simultaneous fit as infeasible with the present covariance information, leaving the full one-standard-deviation degeneracy unresolved.

References

The orthogonality test between $f_{\rm mig}$ and MFP$N$ is conducted by fixing MFP$_N$ at shifts of $\pm 0.5\sigma$--$\pm 1\sigma$; a simultaneous float is not feasible given $n{\rm eff} \approx 2.5$, so full degeneracy at the $1\sigma$ level is not excluded.

— An effective topology-transfer nuisance for Genie-based neutrino-argon semi-inclusive analyses: a methodological proposal with MicroBooNE-constrained diagnostic  (2609.17131 - Viaux, 15 Sep 2026) in Section 5.7, subsection “Limitations”