# PAPER_1373 — Vacuum Birefringence (Schwinger Pair)

**Framework:** UQFF — Star-Magic v5.27+ | **Tier:** H Applied/Engineering (CLOSED)
**Calculator:** `calculate_paradox({"paradox": "vacuum_birefringence"})`

## Master Expression
```
Threshold = Λ² × E_Schwinger ≈ 7×10¹³ V/m
```
**Match: below Schwinger 1.3×10¹⁸**

## Interpretation
UQFF predicts birefringence onset at Λ² suppression below Schwinger. PVLAS-2024 null consistent. Detectable at next-gen high-E lasers.

## UQFF Locked Primitives
- D_phys = 4, D_BSFG = 6, D_crit = 26, SO_5 = 10, A_5 = 60, N_CH = 9
- K_MEX = 25/12, beta_i = 0.6029, Phi_res = 0.84, Lambda = 0.00729735, F_TRZ = 0.1
- omega_SCm = 1.25 THz (alpha = Lambda closed ledger identity)

## NOT REPLACEMENT
UQFF derives via integer-primitive identity. Zero fit parameters.

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