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Main Authors: Schippers, Eric, Staubach, Wolfgang
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2506.08160
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author Schippers, Eric
Staubach, Wolfgang
author_facet Schippers, Eric
Staubach, Wolfgang
contents We consider a compact Riemann surface $\mathscr{R}$ with a complex of non-intersecting Jordan curves, whose complement is a pair of Riemann surfaces with boundary, each of which may be possibly disconnected. We investigate conformally invariant integral operators of Schiffer, which act on $L^{2}$ anti-holomorphic one-forms on one of these surfaces with boundary and produce holomorphic one-forms on the disjoint union. These operators arise in potential theory, boundary value problems, approximation theory, and conformal field theory, and are closely related to a kind of Cauchy operator. We develop an extensive calculus for the Schiffer and Cauchy operators, including a number of adjoint identities for the Schiffer operators. In the case that the Jordan curves are quasicircles, we derive a Plemelj-Sokhotski jump formula for Dirichlet-bounded functions. We generalize a theorem of Napalkov and Yulmukhametov, which shows that a certain Schiffer operator is an isomorphism for quasicircles. Finally, we characterize the kernels and images, and derive index theorems for the Schiffer operators, which will in turn connect conformal invariants to topological invariants.
format Preprint
id arxiv_https___arxiv_org_abs_2506_08160
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Scattering theory on Riemann surfaces I: Schiffer operators, cohomology, and index theorems
Schippers, Eric
Staubach, Wolfgang
Differential Geometry
Algebraic Geometry
Complex Variables
53C56, 51M15, 30F15, 30F30
We consider a compact Riemann surface $\mathscr{R}$ with a complex of non-intersecting Jordan curves, whose complement is a pair of Riemann surfaces with boundary, each of which may be possibly disconnected. We investigate conformally invariant integral operators of Schiffer, which act on $L^{2}$ anti-holomorphic one-forms on one of these surfaces with boundary and produce holomorphic one-forms on the disjoint union. These operators arise in potential theory, boundary value problems, approximation theory, and conformal field theory, and are closely related to a kind of Cauchy operator. We develop an extensive calculus for the Schiffer and Cauchy operators, including a number of adjoint identities for the Schiffer operators. In the case that the Jordan curves are quasicircles, we derive a Plemelj-Sokhotski jump formula for Dirichlet-bounded functions. We generalize a theorem of Napalkov and Yulmukhametov, which shows that a certain Schiffer operator is an isomorphism for quasicircles. Finally, we characterize the kernels and images, and derive index theorems for the Schiffer operators, which will in turn connect conformal invariants to topological invariants.
title Scattering theory on Riemann surfaces I: Schiffer operators, cohomology, and index theorems
topic Differential Geometry
Algebraic Geometry
Complex Variables
53C56, 51M15, 30F15, 30F30
url https://arxiv.org/abs/2506.08160