## Action of the Johnson-Torelli group on representation varieties

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- by William M. Goldman and Eugene Z. Xia PDF
- Proc. Amer. Math. Soc.
**140**(2012), 1449-1457 Request permission

## Abstract:

Let $\Sigma$ be a compact orientable surface with genus $g$ and $n$ boundary components $B = (B_1,\dots , B_n)$. Let $c = (c_1,\dots ,c_n)\in [-2,2]^n$. Then the mapping class group $\mathsf {MCG}$ of $\Sigma$ acts on the relative $\mathsf {SU}(2)$-character variety $\mathfrak {X}_{\mathcal {C}}:=\mathsf {Hom}_\mathcal {C}(\pi ,\mathsf {SU}(2))/\mathsf {SU}(2)$, comprising conjugacy classes of representations $\rho$ with $\mathfrak {tr}(\rho (B_i)) = c_i$. This action preserves a symplectic structure on the smooth part of $\mathfrak {X}_{\mathcal {C}}$, and the corresponding measure is finite. Suppose $g =1$ and $n = 2$. Let $\mathcal {J} \subset \mathsf {MCG}$ be the subgroup generated by Dehn twists along null homologous simple loops in $\Sigma$. Then the action of $\mathcal {J}$ on $\mathfrak {X}_{\mathcal {C}}$ is ergodic for almost all $c$.## References

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## Additional Information

**William M. Goldman**- Affiliation: Department of Mathematics, University of Maryland, College Park, Maryland 20742
- MR Author ID: 74725
- ORCID: 0000-0002-4143-6404
- Email: wmg@math.umd.edu
**Eugene Z. Xia**- Affiliation: Department of Mathematics, National Center for Theoretical Sciences, National Cheng-kung University, Tainan 701, Taiwan
- Email: ezxia@ncku.edu.tw
- Received by editor(s): April 26, 2010
- Received by editor(s) in revised form: December 24, 2010
- Published electronically: July 26, 2011
- Additional Notes: The first author gratefully acknowledges partial support by National Science Foundation grant DMS070781.

The second author gratefully acknowledges partial support by the National Science Council, Taiwan, with grants 96-2115-M-006-002 and 97-2115-M-006-001-MY3. - Communicated by: Bryna Kra
- © Copyright 2011
American Mathematical Society

The copyright for this article reverts to public domain 28 years after publication. - Journal: Proc. Amer. Math. Soc.
**140**(2012), 1449-1457 - MSC (2010): Primary 57M05, 22D40, 13P10
- DOI: https://doi.org/10.1090/S0002-9939-2011-10972-9
- MathSciNet review: 2869130