The exact price of local realism in CHSH experiments: a measurement-dependence-detection trade-off surface, a moir'e phase-locking mechanism that saturates it, and an unmeasured fringe in the fourfold coincidence sum
The research maps how much measurement dependence ($M$) is needed for local hidden-variable theories to explain observed CHSH test results based on detector efficiency ($\eta_{\rm eff}$). It finds an exact price surface, proving that pure detection models cannot simultaneously explain quantum correlations and angle-independent coincidence rates. A specific mechanism, moiré phase locking, saturates this bound.