The DELPHI and ALEPH experiments have released new results of the Fermi-Dirac correlations for pp (\bar{ p} \bar{ p}) and Bose-Einstein correlations for K^0_s K^0_s. Both experiments measure very small source radius for protons R \sim 0.1 fm. The source dimension for K^0_s K^0_s is in agreement with the previous measurements for K^+ K^-, K^0_s K^0_s. These results, together with earlier LEP measurements, establish the dependence of the correlation radius on the hadron mass. This paper discusses some of the attempts to describe this phenomenon.
Categories: hep-ex