# UTFANSWF QCD Nucleon Mass-Response Prediction Contract — FROZEN
Date: 2026-08-19 America/New_York
Status: frozen before comparison to external sigma-term/mass-sensitivity determinations

## Goal
Use the already-frozen v23 CLS N_f=2+1 isoQCD nucleon fit to generate new target-free continuum quark-mass-response outputs.

## Inputs fixed before target comparison
- Frozen v23 RGI-coordinate ensemble table: `PROTON_ORIGIN_CLS_RGI_QUARK_INPUT_V2_2026-08-16.csv`.
- Same five declared fit ansatze and AICc model averaging as the v23 proton-origin hardening: L, Ql, Qmix, LcutM, QlCutM.
- Physical RGI quark coordinates: M_ud=0.00470 GeV, M_s=0.1270 GeV.
- Fixed physical reference scale sqrt(t0)=0.7364089479793612 GeV^-1.
- Continuum evaluation c=0.

## Blindness
No nucleon sigma term, scalar matrix element, strangeness content, or external quark-mass derivative is used to select a model, coefficient, weighting, or stopping rule.

## Primary outputs
At fixed reference sqrt(t0), define
  D_ud = d M_N / d M_ud,
  D_s  = d M_N / d M_s.
Because x_q=sqrt(t0) M_q and M_N=Y_N/sqrt(t0), at fixed sqrt(t0), D_q = partial Y_N / partial x_q.
Also report
  Sigma_ud^(t0-fixed)=M_ud D_ud,
  Sigma_s^(t0-fixed)=M_s D_s,
and logarithmic sensitivities f_ud=Sigma_ud/M_N and f_s=Sigma_s/M_N.

## Claim boundary
These are UTFANSWF internally executed predictions of the *fixed-reference-scale RGI mass response of the frozen v23 isoQCD fit*. They are not promoted as physical Feynman-Hellmann sigma terms unless the quark-mass derivative of the scale-setting observable t0 is separately derived and included.
