The imperfect Boson gas supplemented with a gentle repulsive interaction is completely solved. In particular, it is proved that it has nonextensive Bose-Einstein condensation, i.e., there is condensation without macroscopic occupation of the ground (k = 0) state level. (C) 1999 American Institute of Physics. [S0022-2488(99)03902-X].
- Bose-Einstein condensation