Hyperon Spin Correlation in High-Energy Heavy-Ion Collisions.

Recent experimental data show an unexpectedly large spin alignment of ϕ mesons in high-energy heavy-ion collisions, which can be explained by short-distance fluctuations of strong-force fields (vector ϕ fields) within the constituent-quark model. We calculate the hyperon spin correlations within the same model, taking into account hydrodynamic effects and a ϕ field fluctuating in space-time according to a Gaussian distribution. The ΛΛ[over ¯] spin correlation induced by the ϕ field is shown to be negative as opposed to that of ΛΛ or Λ[over ¯]Λ[over ¯]. We thus propose a new net spin-correlation observable as a sensitive probe to separate strong-force effects from hydrodynamic ones. With the strength of the field fluctuations extracted from the observed ϕ spin alignment, we predict the collision-energy dependence of the hyperon spin correlations and also investigate the dependence of the net spin correlation on azimuthal-angle and rapidity difference.