Modular equations of order $p$ and Theta functions

We study the vector Dyson equation $$-\frac{1}{m(z)}=z\mathbf{1}-\mathbf{a}+Sm(z),$$ with parameter $z$ in the complex upper half-plane $\mathbb{C}_+$, where $\mathbf{a}\in\mathbb R^d$ and $S$ is a nonnegative matrix, not necessarily symmetric. This equation has a unique vector solution $m(z)\in\mathbb{C}_+^d$, for which we establish a complete measure decomposition and prove regularity. We then develop a graph-theoretic approach to the singularity and stability problem for non-symmetric matrices $S$. The graph structure of $S$ identifies the possible degeneracies of the stability operator as $z$ approaches the real axis. In particular, for non-backtracking matrices, we prove square-root growth at regular edges, cubic-root growth at regular cusps, and complete stability estimates. We also obtain the corresponding estimates for symmetric matrices in the periodic setting.

math.CV↗

arXiv2026

Jacobi Endpoint Pencils and Sharp Interlacing for Centered Binomial Samples

We study interlacing between real polynomial quotients obtained from centered binomial samples of a fixed even or odd real entire function at consecutive odd degrees. For sources of order at most one, we determine the optimal vertical-strip half-widths guaranteeing weak interlacing for every adjacent pair: $\sqrt{15/28}$ for even sources and the explicit algebraic constant $h_*\approx 1.0656$ for odd sources. These constants are forced by the first nontrivial pair and suffice at every degree. Under the same sharp bounds, nonpolynomial sources have simple zeros in $(-2,2)$ and strict interlacing at every positive index. We also prove an eventual result: if a nonpolynomial source has growth order less than two and only finitely many zeros off the imaginary axis, then all sufficiently high adjacent quotients have simple interior zeros and strictly interlace; the starting index depends only on the finite factor formed from those zeros. The proof turns the sampling problem into an interval real-rootedness problem for a Jacobi differential operator. For fixed degree, we also determine the maximal range of scalar shifts preserving real-rooted polynomials with at most one zero outside the interval. Applications give strict interlacing for quotients attached to completed Dedekind zeta derivatives and to successive centered blocks of critical values of self-dual newforms satisfying explicit spacing and parity conditions.

math.CV↗

arXiv2026

Local-to-global maximality for plurisubharmonic functions with locally analytic singularities

We prove that a locally maximal plurisubharmonic function on a domain in $\bC^n$, $n\geq2$, is maximal if it has locally analytic singularities with a two-sided locally bounded remainder. Using McAdam's theorem, we show that local maximality forces the analytic spread of each defining ideal to be less than $n$. We use normalized blow-ups and Siu's analyticity theorem to compare singularities through generic divisorial Lelong numbers. We also obtain a criterion for maximality in terms of maximality outside the pole set and the analytic spread of the local defining ideals.

math.CV↗