Casimir effect for a dilute dielectric ball at finite temperature - art. no. 025013

The Casimir effect at finite temperature is investigated for a dilute diele ctric ball; i.e., the relevant internal and free energies are calculated. T he starting point in this study is a rigorous general expression for the in ternal energy of a system of noninteracting oscillators in terms of the sum over the Matsubara frequencies. Summation over the angular momentum values is accomplished in a closed form by making use of the addition theorem for the relevant Bessel functions. For removing the divergences the renormaliz ation procedure is applied that has been developed in the calculation of th e corresponding Casimir energy at zero temperature. The behavior of the the rmodynamic characteristics in the low and high temperature limits is invest igated.