Physical Review Letters
Thermodynamics of an Ultrarelativistic Ideal Bose Gas
Howard E. Haber, H. Arthur Weldon
Abstract
We discuss the properties of an ideal relativistic Bose gas with nonzero chemical potential $\ensuremath{\mu}$ (i.e., with net charge) but differ from all previous discussions by including the effects of antiparticles. We obtain for the first time the relevant high-temperature expansion, emphasizing the constraint $|\ensuremath{\mu}|<~m$, and show that a box of massless particles can have a net charge even though $\ensuremath{\mu}=0$. Finally, we discuss the properties of Bose-Einstein condensation for both massless and massive bosons in $d$ space dimensions.