0.04650 ± 0.01602
Kud = d ln MN / d ln mud at fixed t0.
NP-01 · August 19, 2026
Light-Quark → Nucleon-Mass Response
A frozen fixed-t0 RGI light-quark response curve survives lattice-spacing robustness checks from −20% through +20% without promoting the result to a physical sigma term.
Frozen response
The result is a controlled local response, not a physical sigma-term claim.
43.76 ± 14.42 MeV
Σud(t0 fixed). This label is intentionally retained to prevent promotion to a physical sigma term.
24 ensembles
Five lattice spacings enter the frozen response and leave-one-β robustness audit.
NP-01 verdict: PASS. The sign and monotonic direction survive every leave-one-lattice-spacing rerun; the physical sigma-term promotion is explicitly superseded.
Prediction curve
Finite light-quark shifts produce a frozen nucleon-mass response.
| Δmud | Predicted ΔMN | Conservative σ | Leave-one-β central range |
|---|---|---|---|
| −20% | −8.808 MeV | 2.940 MeV | −10.448 to −6.825 MeV |
| −10% | −4.390 MeV | 1.456 MeV | −5.202 to −3.403 MeV |
| −5% | −2.192 MeV | 0.725 MeV | −2.596 to −1.699 MeV |
| +5% | +2.185 MeV | 0.719 MeV | +1.694 to +2.585 MeV |
| +10% | +4.362 MeV | 1.429 MeV | +3.384 to +5.159 MeV |
| +20% | +8.697 MeV | 2.826 MeV | +6.750 to +10.275 MeV |
Robustness
The important part is the direction surviving the lattice-spacing audit.
The central fixed-t0 response remains positive under every leave-one-β rerun. Curvature and strange-response promotions did not survive the same level of scrutiny and are therefore not carried as predictions.
β omitted → Σud(t0 fixed) central value (MeV)3.40 → 33.94 · 3.46 → 43.00 · 3.55 → 51.81 · 3.70 → 34.91 · 3.85 → 44.08
What this does not say
It is not a direct physical pion-nucleon sigma-term determination.
It does not promote the earlier light-curvature result.
It does not promote the strange response.
The prediction is the fixed-t0 response curve and its robustness envelope.
Reproducibility path
Find the exact frozen inputs inside the verified bundle.
python -m harness.run_all_gates
Bundle paths:
research/new_predictions/reproduce_new_predictions.pyresearch/new_predictions/support/UTFANSWF_V23_LIGHT_QUARK_NUCLEON_RESPONSE_CURVE_FROZEN_2026-08-19.jsonresearch/new_predictions/support/UTFANSWF_V23_QCD_RESPONSE_ROBUSTNESS_SUPERSESSION_2026-08-19.jsonresults/new_predictions/result.json