1936 — The π/8 Accounting: Branch Cut, Exact Fiber in the Valley Set, and a Recorded Residual (WP19)
Date: 2026-08-23 Author: marici.Figueiredo Status: established as stated; one unresolved observation recorded in §5 Supersedes: nothing. Completes the flavor brief's WP4 at the level of the paper's ensemble claim. Consistent with 1911 (WP14b inheritance), 1929/1934 (WP16–WP18 fiber structure).
1. Question
Account for the fitted ensemble's loop-phase clustering near multiples of π/8 (the brief's fourth work package), keeping the three claims separate:
- phase values empirically cluster near π/8 multiples;
- a Yukawa-triangle angle equals a CKM angle at leading order;
- a UV symmetry dynamically selects the simple phase.
All exact-fit solves below are physical10-fiber solves over the fit
point p*. Per the fiber-claim policy they certify finite ambiguity,
never uniqueness; every converged root's sheet membership is certified
by its physical16 image against the two quotient sheets over p*.
2. Branch cut (exact)
The two cos δ sheets over p* (WP18) are not both viable against the paper's 17-observable fit:
- small-δ sheet (cos δ > 0): χ² = 3.3628, below the 3σ/7-dof cut 20.28;
- large-δ sheet (cos δ < 0): χ² = 651.19, top pulls γ +16.3σ, |Vtd| +14.0σ, β −10.3σ, α −9.1σ.
The ensemble of viable textures lives entirely on the cos δ > 0 sheet. The two-sheetedness of the measured ten-coordinate projection (1934) is therefore resolved by data with overwhelming margin: the second sheet never entered the paper's fit, and no ensemble property may be attributed to it.
3. The exact fiber is contained in the scan's valley set (certified)
A dense multi-start completion of the viable-sheet exact fiber at p* (class-phase anchors + 100 uniform phase anchors × 40 restarts per orbit; residual < 1e-7; physical16 branch gate) was run for every orbit whose WP15b dominant classes (χ²_min < 4) were not already matched to the sampled atlas at 1°. Result: in every orbit, each exact viable pinned phase has a dominant scan class within 1° — usually within 0.01°:
| orbit | exact pinned phases (deg) | matching scan classes (deg) |
|---|---|---|
| 0 | 42.831, 69.723 | 42.83, 69.72 |
| 4 | 46.861, 89.717 | 46.86, 89.73 |
| 5 | 21.671, 22.821 | 21.67, 22.82 |
| 7 | 89.717 | 89.69, 89.73 |
| 10 | 22.866, 23.890 | 22.87, 23.89 |
| 11 | 89.733 | 89.69, 89.73 |
| 13 | 89.717 | 89.69, 89.73 |
| 14 | 22.821 | 22.82 |
| 15 | 89.717 | 89.69, 89.73 |
| 16 | 68.922, 89.513 | 68.92, 89.51 |
| 17 | 89.733 | 89.69, 89.73 |
(orbits 2, 6, 9 needed no completion: all their dominant classes matched the sampled atlas phases in the first pass). The exact fit the paper implicitly solves is therefore a subset of the scan's viable minima, and the ensemble's phase content includes the exact fiber's phases.
4. The scan's extra valleys, and a falsified intermediate hypothesis
The intermediate hypothesis "every dominant class phase is a small perturbation of its own orbit's exact pinned phase" is falsified: 34 class records sit 20–66° from their orbit's viable pinned set. These are not defects and not bookkeeping mismatches (orbit indexing verified aligned between WP15b and WP18; identical χ² floor 3.36 at both valley types). They are additional, distinct viable χ² minima in the same charts — other physical quotient points inside the 3σ data ellipsoid.
Two structural facts about them:
- Sibling orbits share the valley multiset. Orbits 7, 11, 13, 15, 17 present the same valley phases {23.67, 46.86/46.94, 89.69/89.73}; orbit 4 presents the same set plus its own exact valley at 46.861.
- The exact p valley occupies different members of the shared set in different charts*: p* sits at folded phase 46.861 in orbit 4's chart and at 89.717 in orbit 7's chart. This is WP11's chart-dependence of the loop phase operating inside the fit ensemble — the same physical point carries different chart phases in sibling presentations, while the ensemble of physical minima is chart independent.
5. The accounting, and its boundary
Established at the level of the paper's claim:
- Every dominant class phase in the 134-class ensemble lies within 2.22° of a window center {22.5°, 45°, 67.5°, 90°}; claim 1 of WP4 is reproduced exactly as an empirical statement.
- For the exact-fiber (p*) valleys the mechanism is now exact: (i) the measured CKM angles at p* (α = 89.224°, β = 22.801°, γ = 67.976°) lie within ~1° of 4π/8, π/8, 3π/8; (ii) WP14b inheritance (ledger 1911) pins the chart loop phase to the CKM-angle data, J² = ρ² sin²φ per chart; (iii) the window binning (half-width 11.25°) absorbs the rest. Class multiplicities are scan-basin weights, not physics.
- No lattice attractor and no UV quantization law is needed or indicated. Claim 3 of WP4 finds no support anywhere in the ensemble structure: nothing selects the simple phase beyond the measured CKM angles themselves.
Recorded residual (unresolved observation). The extra valleys of §4
also hug the window centers within ~2°, and inheritance at p* does not
explain their tightness: each extra valley is a different physical
point on a different sheet of the chart map, with its own ρ, and
arcsin(J/ρ) on those sheets has no established reason to land near a
π/8 multiple. Candidate mechanisms: per-valley inheritance with
sheet-specific ρ; χ²-floor selection of φ through next-to-leading
observable dependence. Deciding between them requires per-valley
physical16 data that WP15b did not store. This is recorded, not
smoothed over: the "accounting" of the clustering is complete for the
exact fiber and empirical for the extra valleys.
6. Consequence for the sector question
WP4 is hereby closed at the level of the paper's evidence. The π/8 clustering is the measured near-π/8-ness of the CKM angles transported into chart phase coordinates by inheritance, plus binning — not an independent quantization phenomenon. This removes the last candidate "conspicuous coincidence" that could have been promoted to a UV law, and it leaves the sector assessment where WP11–WP18 put it: the flavor carrier is the physical quotient with its invariant readout; sparse textures are charts; the loop phase is chart data.
7. Artifacts
research/flavor/checkers/wp19_pi8_accounting.pyresearch/flavor/checkers/wp19b_valley_coverage.pyresearch/flavor/results/wp19_pi8_accounting.jsonresearch/flavor/results/wp19b_valley_coverage.json
Reproduce:
cd research/flavor
./.venv/Scripts/python checkers/wp19_pi8_accounting.py # slow: dense LM solves
./.venv/Scripts/python checkers/wp19b_valley_coverage.py # fast: stored artifacts only