An Explicit Entire Function of Order One with All Zeros on a Line and Bounded in a Half-Plane
Ralph Furmaniak
TL;DR
The paper constructs an explicit order-$1$ entire function $Ξ_c(s)$ with all zeros on the critical line $Re(s)=1/2$ and a symmetry $Ξ_c(s)=Ξ_c(1-s)$, together with a normalized ratio $Z_c(s)$ that remains bounded for $Re(s)>1$ yet blows up on the line $Re(s)=1$. This is achieved via a Hadamard product with carefully perturbed zeros, guided by a Fourier-analytic mechanism that links the zero perturbations to a damped Dirichlet-series component, and a dyadic large-sieve argument that yields unconditional control. The authors further show that the ratio $Z_c/Z_0$ is itself a Dirichlet series with a generalized Euler product, bounded in $Re(s)>1$ and unbounded on $Re(s)=1$, with all zeros on the critical line; its zeros/poles reflect the perturbed and unperturbed spectra. A spectral identity connects the perturbations to a main Fourier sum, and a Phragmén–Lindelöf transfer explains the sharp bounded/unbounded transition. Numerically, the zeros exhibit highly regular spacing and value distributions that are isotropic but constrained, highlighting a distinct contrast with the microscopic GUE statistics of the Riemann zeta function. The construction demonstrates that an RH-like zero distribution can coexist with a sigma-1 transition, providing a concrete, analyzable object that straddles essential features of $ζ$ without its arithmetic complexity.
Abstract
We construct a single explicit entire function $Ξ_c(s)$ of order 1, with all zeros provably on $Re(s) = 1/2$, satisfying a functional equation $Ξ_c(s) = Ξ_c(1-s)$, whose normalized form $Z_c(s) = Ξ_c(s)/[\tfrac{1}{2}s(s-1)π^{-s/2}Γ(s/2)]$ is uniformly bounded for $Re(s) > 1 + δ$ yet satisfies $\sup_t|Z_c(1+it)| = +\infty$. The function thus satisfies an analogue of the Riemann Hypothesis together with the sharp bounded/unbounded transition at $σ= 1$ characteristic of $ζ$. The construction uses Hadamard products with controlled zero perturbations; the transition is proved unconditionally via a dyadic large-sieve argument and a Phragmén-Lindelöf transfer.
