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Pabitra Barman

Publications and source records attributed to Pabitra Barman.

3 recordsLinked to original sources

Entropy and domination for quasi-Hitchin representations

Let $S$ be a closed oriented surface of genus $g\geq 2$. We consider an $n$-pleated representation $ρ: π_1(S) \to \mathrm{PSL}_n(\mathbb{C})$ obtained by bending a Hitchin representation $ρ_0:π_1(S) \to \mathrm{PSL}_n(\mathbb{R})$ along a maximal geodesic lamination. The space of such $n$-pleated representations was recently introduced by Maloni-Martone-Mazzoli-Zhang who provided a parametrization via shear-bend cocycles. Our main result is that $ρ_0$ dominates $ρ$ in the Hilbert length spectrum and the translation-length spectrum, with a strict domination for $\textit{most}$ curves, that we call $\textit{statistical}$ domination. Using this, we prove some entropy rigidity results: namely, the Hilbert entropy of any quasi-Hitchin representation in the bending fiber is strictly greater than that of $ρ_0$, the same for the translation length entropy when $ρ_0$ is $n$-Fuchsian, and in the latter case a new proof that for hyperconvex representations the Hausdorff dimension of the full limit set increases. The proof involves analyzing the weighted planar networks for finite approximants of the monodromy matrix, and establishing a strict matrix domination for generic monodromy using the equidistribution of closed geodesics in the unit tangent bundle of $S$.

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On the domination of surface-group representations in $\mathrm{PU}(2,1)$

This article explores surface-group representations into the complex hyperbolic group $\mathrm{PU}(2,1)$ and presents domination results for a special class of representations called $T$-bent representations. Let $S_{g,k}$ be a punctured surface of negative Euler characteristic. We prove that for a $T$-bent representation $ρ: π_1(S_{g,k}) \rightarrow \mathrm{PU}(2,1)$, there exists a discrete and faithful representation $ρ_0: π_1(S_{g,k}) \rightarrow \mathrm{PO}(2,1)$ that dominates $ρ$ in the Bergman translation length spectrum, while preserving the lengths of the peripheral loops.

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Dominating surface-group representations via Fock-Goncharov coordinates

Let $S$ be a punctured surface of negative Euler characteristic. We show that given a generic representation $ρ:π_1(S) \rightarrow \mathrm{PSL}_n(\mathbb{C})$, there exists a positive representation $ρ_0:π_1(S) \rightarrow \mathrm{PSL}_n(\mathbb{R})$ that dominates $ρ$ in the Hilbert length spectrum as well as in the translation length spectrum, for the translation length in the symmetric space $\mathbb{X}_n= \mathrm{PSL}_n(\mathbb{C})/\mathrm{PSU}(n)$. Moreover, the $ρ_0$-lengths of peripheral curves remain unchanged. The dominating representation $ρ_0$ is explicitly described via Fock-Goncharov coordinates. Our methods are linear-algebraic, and involve weight matrices of weighted planar networks.

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