English

Branched projective structures on a Riemann surface and logarithmic connections

Complex Variables 2018-08-15 v1 Algebraic Geometry

Abstract

We study the set PS{\mathcal P}_S consisting of all branched holomorphic projective structures on a compact Riemann surface XX of genus g1g \geq 1 and with a fixed branching divisor S:=i=1dnixiS:= \sum_{i=1}^d n_i\cdot x_i, where xiXx_i \in X. Under the hypothesis that ni=1n_i=1, for all ii, with dd a positive even integer such that d2g2d \neq 2g-2, we show that PS{\mathcal P}_S coincides with a subset of the set of all logarithmic connections with singular locus SS, satisfying certain geometric conditions, on the rank two holomorphic jet bundle J1(Q)J^1(Q), where QQ is a fixed holomorphic line bundle on XX such that Q2=TXOX(S)Q^{\otimes 2}= TX\otimes {\mathcal O}_X(S). The space of all logarithmic connections of the above type is an affine space over the vector space H0(X,KX2OX(S))H^0(X, K^{\otimes 2}_X \otimes {\mathcal O}_X(S)) of dimension 3g3+d3g-3+d. We conclude that PS{\mathcal P}_S is a subset of this affine space that has codimenison dd at a generic point.

Keywords

Cite

@article{arxiv.1808.04555,
  title  = {Branched projective structures on a Riemann surface and logarithmic connections},
  author = {Indranil Biswas and Sorin Dumitrescu and Subhojoy Gupta},
  journal= {arXiv preprint arXiv:1808.04555},
  year   = {2018}
}
R2 v1 2026-06-23T03:33:03.869Z