Some thermal properties of ideal gas

Abstract In this article, we investigate the thermal properties of non-relativistic many-body systems at finite temperatures and chemical potential. We compute the one-point function of various operators constructed out of the basic fields in ideal bosonic and fermionic many-body systems. The one-point function is non-zero only for operators with zero particle numbers. We investigate these operators in $$\mathbb R^d$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>R</mml:mi> <mml:mi>d</mml:mi> </mml:msup> </mml:math> and $$\mathbb R^d_{+}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>R</mml:mi> <mml:mo>+</mml:mo> <mml:mi>d</mml:mi> </mml:msubsup> </mml:math> , i.e. a flat space with a planar boundary. Furthermore, we compute the Green’s function and using the operator product expansion, we express it in terms of the thermal one-point function of the higher spin currents. On $$\mathbb R^d_{+}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>R</mml:mi> <mml:mo>+</mml:mo> <mml:mi>d</mml:mi> </mml:msubsup> </mml:math> , the operator product expansion allows to express the bulk-bulk Green’s function in terms of the thermal Green’s function of the boundary operators. We also study the ideal system by placing it on curved spatial surfaces, specifically spherical surfaces. We compute the partition function and Green’s function on spheres, squashed-sphere and hemispheres. Finally, we compute the large radius corrections to the partition function and Green’s function by expanding in the large radius limit.