A theory of generalized Lamé curves

Fuente: arXiv
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Auteurs principaux: Chou, You-Cheng, Wang, Chin-Lung, Wu, Po-Sheng
Format: Preprint
Publié: 2026
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author Chou, You-Cheng
Wang, Chin-Lung
Wu, Po-Sheng
author_facet Chou, You-Cheng
Wang, Chin-Lung
Wu, Po-Sheng
contents We study the generalized Lamé equation on an elliptic curve $E$ with multiple singularities. By restricting to the locus admitting solutions with quasi-periodic properties, we construct two curves: (i) The generalized Lam'e curve: with $n:=\sum\nolimits_{i=1}^r n_i\in\mathbb Z_{\geq 0}$, we construct $\mathcal{Y}_{\mathbf n}(\mathbf p;τ)$, which lies in an affine bundle over $Sym^n E$ and parametrizes generalized Hermite--Halphen ansatz solutions. (ii) The log-free curve: each $n_i\in\frac12\mathbb N$ gives a polynomial equation in the accessory parameters. This leads to a non-complete intersection variety $V_{\mathbf{n}}(\mathbf{p};τ)$ when all $n_i\in\frac12\mathbb N$. We prove that it is a reduced curve. We analysis the GLC as an algebraic family over the pole configuration space $\mathbf{p}$. We study the shifted addition map \[ σ: Sym^n E\longrightarrow E, \] establishing a generically finite, degree formula. The geometry of boundary degenerations under pole collisions perfectly mirrors the tensor algebra of $\mathfrak{sl}_2(\mathbb{C})$-modules within the BGG category $\mathcal{O}$. We generalize pre-modular forms to a framework of twisted isomonodromic deformations. We construct $(\mathbf{n}, \mathbf{p})$-deformed pre-modular forms parameterized by pseudo-monodromy data $(t,s)$, whose vanishing governs these deformations and factorizes along boundary strata. Iterating these deformations through the boundary allows any arbitrary configuration to be continuously deformed down to the classical Lamé equation. Finally, we prove the Treibich conjecture stated for $r=2$ extra symmetric pairs, as well as its generalizations for $r \leq 4$.
format Preprint
id arxiv_https___arxiv_org_abs_2604_21880
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A theory of generalized Lamé curves
Chou, You-Cheng
Wang, Chin-Lung
Wu, Po-Sheng
Algebraic Geometry
Classical Analysis and ODEs
We study the generalized Lamé equation on an elliptic curve $E$ with multiple singularities. By restricting to the locus admitting solutions with quasi-periodic properties, we construct two curves: (i) The generalized Lam'e curve: with $n:=\sum\nolimits_{i=1}^r n_i\in\mathbb Z_{\geq 0}$, we construct $\mathcal{Y}_{\mathbf n}(\mathbf p;τ)$, which lies in an affine bundle over $Sym^n E$ and parametrizes generalized Hermite--Halphen ansatz solutions. (ii) The log-free curve: each $n_i\in\frac12\mathbb N$ gives a polynomial equation in the accessory parameters. This leads to a non-complete intersection variety $V_{\mathbf{n}}(\mathbf{p};τ)$ when all $n_i\in\frac12\mathbb N$. We prove that it is a reduced curve. We analysis the GLC as an algebraic family over the pole configuration space $\mathbf{p}$. We study the shifted addition map \[ σ: Sym^n E\longrightarrow E, \] establishing a generically finite, degree formula. The geometry of boundary degenerations under pole collisions perfectly mirrors the tensor algebra of $\mathfrak{sl}_2(\mathbb{C})$-modules within the BGG category $\mathcal{O}$. We generalize pre-modular forms to a framework of twisted isomonodromic deformations. We construct $(\mathbf{n}, \mathbf{p})$-deformed pre-modular forms parameterized by pseudo-monodromy data $(t,s)$, whose vanishing governs these deformations and factorizes along boundary strata. Iterating these deformations through the boundary allows any arbitrary configuration to be continuously deformed down to the classical Lamé equation. Finally, we prove the Treibich conjecture stated for $r=2$ extra symmetric pairs, as well as its generalizations for $r \leq 4$.
title A theory of generalized Lamé curves
topic Algebraic Geometry
Classical Analysis and ODEs
url https://arxiv.org/abs/2604.21880