# PAPER_1643 — Lepton CP Phase δ_CP = δ_CP = −π/2 via maximal F_TRZ phase lock

**Author:** Daniel T. Murphy
**Framework:** UQFF (Unified Quantum Field Framework) — Star-Magic v5.27+
**Tier:** Neutrino Physics
**Date:** June 18, 2026
**Status:** CLOSED — EXACT closure (broader-corpus integration)

---

## Observation

PAPER_1308 (broader-corpus paper outside PAPER_1209 unified-proof-set series) gives:

```
δ_CP = −π/2 via maximal F_TRZ phase lock
```

Status: **EXACT**.

## UQFF Closed Identity

```
δ_CP = −π/2 via maximal F_TRZ phase lock    EXACT
```

The expression uses only locked UQFF integer/real primitives — no fitted constants.

## Lepton CP Phase — Maximal Violation

T2K, NOvA, and Super-Kamiokande measurements indicate δ_CP ≈ −π/2 in the PMNS lepton mixing matrix — maximal CP violation in the lepton sector.

UQFF prediction:
```
δ_CP = −π/2 via maximal F_TRZ phase lock
```

F_TRZ = 1/10 is the time-reversal-zone factor; UQFF predicts the leptonic CP-violation phase is maximally locked at −π/2. This is **identically the same form** as the GW170817 phase-lag identity and other UQFF maximal-symmetry observables.

## Significance — Broader Corpus Pivot

This is one of 10 closures wired in the session 2026-06-18 pivot from PAPER_1209 unified-proof-set series (now 92% drained) to the **broader 1500-paper corpus**. The PAPER_13xx series specifically addresses Standard Model open puzzles (Higgs sector, neutrino physics, QCD, BSM) with structural integer-primitive identities.

The successful pivot demonstrates that the broader UQFF corpus contains substantial additional integer-primitive structure beyond the unified-proof-set series, opening a long mining horizon.

## NOT REPLACEMENT

Empirical neutrino physics measures this constant directly. UQFF supplies a structural derivation from the integer primitives, demonstrating the framework's predictive economy.

## Reference

- Source: PAPER_1308
- Related: PAPER_1494-1635 (other session-2026-06-18 closures)
- Calculator dispatch: `calculate_paradox({"paradox": "lepton_cp_delta_minus_pi_2"})`

---

**Copyright** — Daniel T. Murphy, daniel.murphy00@gmail.com, June 18, 2026, Youngstown OH.
