Heat kernel-zeta function relationship coming from the classical moment problem
Résumé
By using ideas and strong results borrowed from the classical moment problem, we show how -under very general conditions- a discrete number of values of the spectral zeta function (associated generically with a non-decreasing sequence of numbers, and not necessarily with an operator) yields all the moments corresponding to the density of states, as well as those of the partition function of the sequence (the two basic quantities that are always considered in a quantum mechanical context). This goes beyond the well known expression of the small-t asymptotic expansion of the heat kernel of an operator in terms of zeta function values. The precise result for a given situation depends dramatically on the singularity structure of the zeta function. The different specific situations that can appear are discussed in detail, using seminal results from the zeta function literature. Attention is paid to formulations involving zeta functions with a non-standard pole structure (as those arising in noncommutative theories and others). Finally, some misuses of the classical moment problem are pointed out.