DOI: 10.1515/forum-2023-0308 ISSN: 0933-7741

A remark on the automorphisms of the moduli space of logarithmic λ-connections over a curve

Anoop Singh

Abstract

Let X be a compact Riemann surface of genus

g ≥ 3 {g\geq 3}
and let S be a finite subset of X . Let ξ be a fixed line bundle over X of degree d . We consider the moduli space
ℳ Hod ⁢ ( X , S , ξ ) {\mathcal{M}_{\rm Hod}(X,S,\xi)}
of logarithmic λ-connections singular over
S ⊂ X {S\subset X}
of rank n and degree d with fixed residues in the center of
𝔤 ⁢ 𝔩 ⁢ ( n , ℂ ) {\mathfrak{gl}(n,\mathbb{C})}
, where n and d are mutually coprime. We determine the Picard group and investigate the automorphism group of
ℳ Hod ⁢ ( X , S , ξ ) {\mathcal{M}_{\rm Hod}(X,S,\xi)}
. Let
ℳ Hod ′ ⁢ ( X , S , ξ ) ⊂ ℳ Hod ⁢ ( X , S , ξ ) {\mathcal{M}^{\prime}_{\rm Hod}(X,S,\xi)\subset\mathcal{M}_{\rm Hod}(X,S,\xi)}
be the open subvariety consisting of those logarithmic λ-connections whose underlying vector bundle is stable. We show that there is a natural compactification of the moduli space
ℳ Hod ′ ⁢ ( X , S , ξ ) {\mathcal{M}^{\prime}_{\rm Hod}(X,S,\xi)}
. We also recall the logarithmic version of Riemann–Hilbert correspondence which arises from Deligne’s extension theorem, and using this we prove the Torelli-type theorem for
ℳ Hod ⁢ ( X , S , ξ ) {\mathcal{M}_{\rm Hod}(X,S,\xi)}
.