Non-Inertial Response of Correlations: From Scalar Bell Observables to an Extended Correlation Tensor
A standard Bell observable is a scalar correlation associated with a selected pair of local measurement directions. We formulate it as a projection of a complete two-particle correlation tensor and distinguish two angular sectors. The central result is a reversal of the sign multiplying the cosine law: for coincident calibrated settings, the Bell observable is positive for photons and negative for a fermionic singlet. This distinction provides an operational criterion for experimental identification. For photons, the positive sign follows from averaging two projection amplitudes over the complete non-inertial phase interval; the fermionic sign follows from the negative exchange holonomy of the phase--momentum sector. Mapping phase directions to linear-polarizer axes produces the corresponding double-angle dependence. The photon Stokes tensor has positive linear-polarization components and a negative circular-polarization component, whereas the fermionic singlet has an isotropic negative tensor. We introduce a motion-dependent extended tensor and a frequency-dependent non-inertial susceptibility. A phase-synchronous two-arm experiment combines optical modulation, rotation, and seeded multiaxial piezoelectric vibration. Independent motion measurements separate common and differential components and allow controlled variation from correlated to independent and oppositely driven motion; a single rigid platform is the simpler common-frame limit. Bell-setting and state-correlation vectors express the sign reversal as a scalar projection. The construction yields binary joint probabilities and recovers the Tsirelson bound with oppositely signed optimal CHSH combinations.