Fluctuations in the canonical ensemble

The particle number and energy fluctuations in a system of charged particles are studied in the canonical ensemble for nonzero net values of the conserved charge. In the thermodynamic limit, the fluctuations in the canonical ensemble differ from those in the grand canonical ensemble. A system with several species of particles is considered. We calculate the quantum statistical effects that can be taken into account for the canonical ensemble fluctuations in the infinite-volume limit. The fluctuations of the particle numbers in the pion-nucleon gas are considered in the canonical ensemble as an example of the system with two conserved charges---baryonic number and electric charge.