Bose-Einstein correlations: a study of an invariance group

A group of transformations changing the phases of the single particle density matrix, but leaving unchanged the predictions for identical particles concerning the momentum distributions, momentum correlations etc., is identified. Its implications for the determinations of the interaction region from studies of Bose-Einstein correlations are discussed.Comment: 15 pages LateX + one figure ep

Mass dependence of HBT correlations in e^+e^- annihilation

Mass dependence of the effective source radii, observed in hadronic $Z^0$ decays by several LEP I experiments, is analyzed in a model which assumes proportionality between four-momentum of a produced particle and the four-vector describing its space-time position at the freeze-out. It is shown that this relation (commonly accepted in description of high-energy collisions) can explain the data, provided all particles are emitted from a "tube" of $\sim 1$ fm in diameter at a constant proper time $\sim 1.5$ fm.Comment: 15 pages, 3 figure

Bose-Einstein condensation and independent production of pions

The influence of the HBT effect on the momentum spectra of independently produced pions is studied using the method developed earlier for discussion of multiplicity distributions. It is shown that in this case all the spectra and multiparticle correlation functions are expressible in terms of one function of two momenta. It is also shown that at the critical point all pions are attracted into one quantum state and thus form a Bose-Einstein condensate.Comment: 10 pages Latex, one figure as an EPS fil