We discuss a formal derivation of an integral expression for the Li
coefficients associated with the Riemann xi-function which, in particular,
indicates that their positivity criterion is obeyed, whereby entailing the
criticality of the non-trivial zeros. We conjecture the validity of this and
related expressions without the need for the Riemann Hypothesis and discuss a
physical interpretation of this result within the Hilbert-Polya approach. In
this context we also outline a relation between string theory and the Riemann
Hypothesis.Comment: 8 pages, LaTeX, Quantum Theory and Symmetries 6 conference
proceeding
