Surprises from Bose-Einstein correlations

An investigation of the space-time extension of particle sources in the current-ensemble formalism shows that under quite general assumptions exist a quantum statistical (${\mathrm{\pi }}^{+}$ ${\mathrm{\pi }}^{\mathrm{-}}$) correlation and a difference between (${\mathrm{\pi }}^0$ ${\mathrm{\pi }}^0$) and (${\mathrm{\pi }}^{\mathrm{-}}$ ${\mathrm{\pi }}^{\mathrm{-}}$) Bose-Einstein correlations. These effects are found to be enhanced for small momenta and radii.