Small improvements on the Ball-Rivoal theorem and its $p$-adic variant
Li Lai
TL;DR
This work sharpens the Ball–Rivoal theme on the linear independence of $1$ and odd zeta values by tightly integrating Zudilin’s $oldsymbol{igPhi}_n$ denominator method. It yields explicit, non-vanishing linear forms in $1$ and odd zeta values, establishing a near-universal lower bound on the dimension of their $Q$-span for large even $s$, and provides a parallel $p$-adic result for $zeta_p(s)$ with an analogous constant. The approach remains explicit and programming-free for the main bounds, while computational parameter tuning delivers a sharper constant of approximately $1.119/(1+ ext{log }2)$ in a broader setting. Complementing this, the paper offers detailed $p$-adic preliminaries via Volkenborn integrals and overconvergent power series, together with a carefully constructed p-adic analogue of Nesterenko’s criterion and asymptotics. The results enhance the understanding of the arithmetic nature of zeta values, deliver explicit non-vanishing linear forms, and extend the Ball–Rivoal framework to the $p$-adic realm with explicit, quantitative bounds.
Abstract
We prove that the dimension of the $\mathbb{Q}$-linear span of $1,ζ(3),ζ(5),\ldots,ζ(s-1)$ is at least $(1.119 \cdot \log s)/(1+\log 2)$ for any sufficiently large even integer $s$. This slightly refines a well-known result of Rivoal (2000) or Ball-Rivoal (2001). Quite unexpectedly, the proof only involves inserting the arithmetic observation of Zudilin (2001) into the original proof of Ball-Rivoal. Although this result is covered by a recent development of Fischler (2021+), our proof has the advantages of being simple and providing explicit non-vanishing small linear forms in $1$ and odd zeta values. Moreover, we establish the $p$-adic variant: for any prime number $p$, the dimension of the $\mathbb{Q}$-linear span of $1,ζ_p(3),ζ_p(5),\ldots,ζ_p(s-1)$ is at least $(1.119 \cdot \log s)/(1+\log 2)$ for any sufficiently large even integer $s$. This is new, it slightly refines a result of Sprang (2020).
