Casimir Geometry as a Probe of Short Range Forces

Casimir force searches provide among the most sensitive laboratory probes of new short range interactions. Existing constraints rely almost exclusively on a single geometry. We show that Casimir geometry constitutes an independent observable, as Yukawa-type interactions and Casimir background exhibit different geometric scaling for bulk forces and surface quantum effects. We derive the first constraints from sphere-sphere and plate-plate geometries, thereby completing the canonical set of Casimir geometries, obtaining the most stringent Casimir-based bounds for $\lambda \lesssim {10}^{-8}\mathrm{m}$. Our results establish geometry as a new handle for systematic searches for short range forces.