Particle number fluctuations in relativistic Bose and Fermi gases

Particle number fluctuations are studied in relativistic Bose and Fermi gases. The calculations are done within both the grand canonical and canonical ensemble. The fluctuations in the canonical ensemble are found to be different from those in the grand canonical one. Effects of quantum statistics strongly increase in the grand canonical ensemble for large chemical potential. This is, however, not the case in the canonical ensemble, and in the limit of large charge density a strongest difference between the grand canonical and canonical ensemble results is observed.