The dependence of the emission size on the hadron mass

The size of the emission volume of pions and kaons, rππ and rKK, were measured in the hadronic Z0 decays through the two-pion and two-kaon Bose–Einstein correlations near threshold. Recently the emitter size of the two identical baryons, ΛΛ(Λ̄Λ̄), was evaluated from the dependence of the fraction of the spin S=1 state on the energy near threshold where it is affected by the Pauli exclusion principle. Here we show that the r dependence on the particle masses, namely the hierarchy rππ>rKK>rΛΛ observed in the Z0 hadronic decays, is well described in terms of the Heisenberg uncertainty principle. A good description can also be obtained via the virial theorem when applied to a general QCD potential. Other available approaches are also discussed.