Predictions → ALP Birefringence
Prediction
ALP Birefringence
A model-dependent ALP field-evolution calculation motivates a β value near 0.27°. Existing birefringence measurements have systematic and model-dependence questions and do not validate a bounce scenario.
Current constraint
Published CMB rotation estimates provide external context only. They are not an in-house validation of the β calculation or evidence that a bounce occurred.
Key results
- A model-dependent ALP calculation motivates β near 0.27°
- External birefringence estimates do not identify a bounce mechanism
- Foreground and estimator systematics remain material
- An injection-recovery exercise checks a pipeline response, not the physical model
Connected work
Surveys: Planck CMB (patch anomalies) · ACT DR6 (needs NaMaster re-run)
Papers: P1A — boundary note · P1B — namaster-proof research software
Timeline
Future CMB measurements may test model-dependent birefringence scenarios; they are not a bounce detection.
Next steps
- openACT re-run with NaMaster + galactic mask + multipole estimator
- openCross-frequency decorrelation for foreground removal
- openPlanck EB cross-spectrum independent measurement
- openTreat future LiteBIRD measurements as one constraint among model alternatives