Analyzing Correlations for spin-1/2 particles and Singlet pairs

TL;DR

This paper reviews the computation of spin correlations in spin-1/2 particles and EPRB pairs, revealing that certain Bell inequalities lack physical meaning under realistic assumptions, and shifts focus from locality to realism.

Contribution

It demonstrates that Bell inequalities with three or four axes are physically meaningless under realistic assumptions, challenging traditional interpretations of quantum correlations.

Findings

Bell inequalities with three or four axes cannot have physical meaning

Certain correlations cannot be evaluated under realistic assumptions

Locality assumptions are unaffected by these results

Abstract

We review the computation of correlations of successive projections of the spin onto axes for spin-1/2 particles and EPRB pairs (in the Singlet state). We assume forms of Realism (at least as general as the Predictive Hidden Variables in the classical Bell's Theory), to review one particle correlations before we further assume Locality and analyze EPRB pairs. To our surprise, we find that the Abstract Bell Inequalities with three or four axes cannot have physical meaning i.e., two spin projections cannot belong to one particle or some correlations that one would need cannot be evaluated. A recent version of Bell's Theory without Locality turns out to be unaffected by our results that refocus the open issues on "realism" rather than "local realism", inviting us to leave locality alone so to speak.