• Subhashis Nag

Articles written in Proceedings – Mathematical Sciences

• Schiffer variation of complex structure and coordinates for Teichmüller spaces

Schiffer variation of complex structure on a Riemann surfaceX0 is achieved by punching out a parametric disc$$\bar D$$ fromX0 and replacing it by another Jordan domain whose boundary curve is a holomorphic image of$$\partial \bar D$$. This change of structure depends on a complex parameter ε which determines the holomorphic mapping function around$$\partial \bar D$$.

It is very natural to look for conditions under which these ε-parameters provide local coordinates for Teichmüller spaceT(X0), (or reduced Teichmüller spaceT#(X0)). For compactX0 this problem was first solved by Patt [8] using a complicated analysis of periods and Ahlfors' [2] τ-coordinates.

Using Gardiner's [6], [7] technique, (independently discovered by the present author), of interpreting Schiffer variation as a quasi conformal deformation of structure, we greatly simplify and generalize Patt's result. Theorems 1 and 2 below take care of all the finitedimensional Teichmüller spaces. In Theorem 3 we are able to analyse the situation for infinite dimensionalT(X0) also. Variational formulae for the dependence of classical moduli parameters on the ε's follow painlessly.

• Canonical measures on the moduli spaces of compact Riemann surfaces

We study some explicit relations between the canonical line bundle and the Hodge bundle over moduli spaces for low genus. This leads to a natural measure on the moduli space of every genus which is related to the Siegel symplectic metric on Siegel upper half-space as well as to the Hodge metric on the Hodge bundle.

• Self-dual connections, hyperbolic metrics and harmonic mappings on Riemann surfaces

The Sampson-Wolf model of Teichmüller space (using harmonic mappings) is shown to be exactly the same as the more recent Hitchin model (utilizing self-dual connections). Indeed, it is noted how the self-duality equations become the harmonicity equations. An interpretation of the modular group action in this model is mentioned.

• # Proceedings – Mathematical Sciences

Current Issue
Volume 129 | Issue 5
November 2019

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019