2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/93228The nonrelativistic singlet state average $\langle ψ|{\vec a}\cdot\vec σ\otimes {\vec b}\cdot\vec σ|ψ\rangle =-\vec a\cdot\vec b $ can be relativistically generalized if one defines spin {\it via\/} the relativistic center-of-mass operator. The relativistic correction is quadratic in $v/c$ and can be measured in Einstein-Podolsky-Rosen-Bohm-type experiments with massive spin-1/2 particles. A deviation from the nonrelativistic formula would indicate that for relativistic nonzero-spin particles centers of mass and charge do not coincide.revtex, 3 pagesQuantum Physicstext