A Note on primitive pairs for graded Lie algebras
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arXiv
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| Format: | Preprint |
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2025
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| author | Chatterjee, Tamanna |
| author_facet | Chatterjee, Tamanna |
| contents | We develop a theory of primitive pairs for $\mathbb{Z}$-graded Lie algebras when the sheaves have coefficients in a field $\Bbbk$ of positive characteristic, providing a graded analogue of the role played by cuspidal pairs in the generalized Springer correspondence. We consider the centralizer $G_0$ of a fixed cocharacter $χ$ in a connected, reductive, algebraic group $G$ and its action on the eigenspaces $\mathfrak{g}_n$ of $χ$. Building on the framework of parity sheaves and the Fourier transform established in \cite{Ch,Ch1}, we show that every indecomposable parity sheaf on $\mathfrak{g}_n$ can be expressed as a direct summand of a complex induced from primitive data on a Levi subgroup. This result extends the fact that, in the graded setting, any indecomposable parity sheaf is direct summand of an induced cuspidal datum \cite{Ch}. This confirms the organizing role of primitive pairs in the block decomposition of the category of $G_0$-equivariant parity sheaves on $\mathfrak{g}_n$. We further establish that primitive pairs on the nilpotent cone induce primitive pairs in the graded setting, and we prove that primitivity is preserved under the Fourier--Sato transform. These results reveal a deep compatibility between the geometry of graded Lie algebras and their representation-theoretic structures, forming the foundation for a graded version of the generalized Springer correspondence in positive characteristic. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2510_24506 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A Note on primitive pairs for graded Lie algebras Chatterjee, Tamanna Representation Theory We develop a theory of primitive pairs for $\mathbb{Z}$-graded Lie algebras when the sheaves have coefficients in a field $\Bbbk$ of positive characteristic, providing a graded analogue of the role played by cuspidal pairs in the generalized Springer correspondence. We consider the centralizer $G_0$ of a fixed cocharacter $χ$ in a connected, reductive, algebraic group $G$ and its action on the eigenspaces $\mathfrak{g}_n$ of $χ$. Building on the framework of parity sheaves and the Fourier transform established in \cite{Ch,Ch1}, we show that every indecomposable parity sheaf on $\mathfrak{g}_n$ can be expressed as a direct summand of a complex induced from primitive data on a Levi subgroup. This result extends the fact that, in the graded setting, any indecomposable parity sheaf is direct summand of an induced cuspidal datum \cite{Ch}. This confirms the organizing role of primitive pairs in the block decomposition of the category of $G_0$-equivariant parity sheaves on $\mathfrak{g}_n$. We further establish that primitive pairs on the nilpotent cone induce primitive pairs in the graded setting, and we prove that primitivity is preserved under the Fourier--Sato transform. These results reveal a deep compatibility between the geometry of graded Lie algebras and their representation-theoretic structures, forming the foundation for a graded version of the generalized Springer correspondence in positive characteristic. |
| title | A Note on primitive pairs for graded Lie algebras |
| topic | Representation Theory |
| url | https://arxiv.org/abs/2510.24506 |