The closed piecewise uniform string revisited
... another one using a Hurwitz zeta function. The latter results in a representation in terms of finite sums over polynomials. Several limiting cases are considered as well, for instance, the high-temperature expansion, which is expressed in terms of the heat kernel coefficients. The vacuum energy has no ultraviolet divergences, and the corresponding heat kernel coefficient is zero due to the constancy of the speed of light. This is in parallel to a similar situation in macroscopic electrodynamics.
1. Brevik ...