The finite-dimensional property (T) conjecture for mapping class groups

From papers

Let SgnS_g^n be a compact oriented surface of genus gg with nn boundary components, and let Mod(Sgn)\mathrm{Mod}(S_g^n) denote its mapping class group. For a finite-dimensional unitary representation ρ\rho of this group, let H1(Mod(Sgn),ρ)H^1(\mathrm{Mod}(S_g^n),\rho) denote group cohomology with coefficients in the associated representation. Finite-dimensional property (T) conjecture. For g3g\geq 3 and n0n\geq 0, every finite-dimensional unitary representation ρ\rho satisfies

H1(Mod(Sgn),ρ)=0.H^1(\mathrm{Mod}(S_g^n),\rho)=0.

This intermediate conjecture is intended to cover unitary quantum representations, including the SU(2)\mathrm{SU}(2) and SO(3)\mathrm{SO}(3) cases. It is related to Daniel Litt's conjecture that irreducible representations of mapping class groups in genus at least 33 should be rigid, but no resolution is given here.

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Sources & referencesView supporting material

Primary source

Pierre Godfard, “Rigidity of SU(2) and SO(3) quantum representations of mapping class groups at prime levels”, arXiv:2511.19795 (2025).

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