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. 
A. Bialas and K. Zalewski (Jagellonian University, Cracow, Poland)