Random walks through the areal Mahler measure: steps in the complex plane
Matilde N. Lalín, Siva Sankar Nair, Berend Ringeling, Subham Roy
TL;DR
This work establishes explicit formulas for the areal Mahler measure $m_{\mathbb{D}}$ for two fundamental polynomial families: $x+y+k$ and $Q_k=(x+1)(y+1)+kz$. By interpreting $m_{\mathbb{D}}$ through the areal Zeta Mahler function and a random-walk framework, the authors derive hypergeometric, dilogarithmic, and modular-analytic expressions that relate $m_{\mathbb{D}}$ to the classical Mahler measure $m$, plus contributions from Deninger-cycle volumes. They present two proofs for the main results in the $x+y+k$ case (a hypergeometric/ZAMM approach and a direct computation), and they extend the methodology to $Q_k$, obtaining density formulas and a detailed expansion of $m_{\mathbb{D}}(Q_k)$ that includes a central volume term $c_0(k)$ with modular significance. The results yield efficient numerical schemes, illuminate connections to special values of $L$-functions and Bloch–Wigner dilogarithms, and reveal geometric (Deninger-cycle) and modular structures underlying areal Mahler measures.
Abstract
We study the areal Mahler measure of the two-variable, $k$-parameter family $x+y+k$ and prove explicit formulas that demonstrate its relation to the standard Mahler measure of these polynomials. The proofs involve interpreting the areal Mahler measure as a random walk in the complex plane and utilizing the areal analogue of the Zeta Mahler function to arrive at the result. Using similar techniques, we also present formulas for a three-variable family $(x+1)(y+1)+kz$ in terms of the standard Mahler measure, along with terms that involve certain hypergeometric functions. For both families we show that its areal Mahler measure is, up to elementary functions, a linear combination of the normal Mahler measure and the volume of the Deninger cycle of the corresponding family.
