# Superzeta Functions: an Overview

Chapter
Part of the Lecture Notes of the Unione Matematica Italiana book series (UMILN, volume 8)

## Abstract

In view of the central symmetry of the set of Riemann zeros, $$\rho \leftrightarrow 1 - \rho$$ which crucially reflects the functional equation (3.26), there is no clear reason to pick either the ρ themselves (with $$\rho \equiv \frac{1}{2} \pm i\tau_{k}, {\rm Re} \tau_{k} > 0$$) or the $$\rho(1 - \rho) = \frac{1}{4} + \tau_{k}^{2}$$ as the basic set upon which to build zeta functions over the Riemann zeros. This is a nonlinear remapping freedom as discussed in Sect. 1.1, which leads to generalized zeta functions of several kinds. This chapter gives an introductory overview of the various possibilities. In decreasing order of analytical tractability, and in our older notation to be soon discarded, we may define: Functions of first kind: $$\sum_{\rho}(x - \rho)^{-s}, \qquad {\rm Re} s > 1;$$ Functions of second kind: $$\sum\limits_{k = 1}^{\infty}(\tau_{k}^{2} + v)^{-\sigma},\qquad \mathfrak{R}\sigma > \frac{1}{2};$$ Functions of third kind: $$\sum\limits_{k = 1}^{\infty}(\tau_{k}^{2} + \tau)^{-s},\qquad {\rm Re} s > 1.$$ In all three kinds the argument (in exponent) is the principal variable, the other one a shift parameter. Each parametric family starts as an analytic function of its argument in its indicated half-plane of convergence, due to (4.7) or (4.26), but it will extend to a meromorphic function in the entire complex plane (of its argument), with a computable singular part. The domain of each shift parameter is left as large as possible: simply, none of the quantities to be raised to a power should lie on the cut $$\mathbb{R}_{-}$$; this will hardly matter with the fairly small parameter values that we will emphasize.

## Keywords

Meromorphic Function Zeta Function Central Symmetry Shift Parameter Riemann Hypothesis
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.