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| Auteurs principaux: | , |
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| Format: | Preprint |
| Publié: |
2025
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| Accès en ligne: | https://arxiv.org/abs/2506.12918 |
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| _version_ | 1866913895435730944 |
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| author | Liu, Ben Nie, Sian |
| author_facet | Liu, Ben Nie, Sian |
| contents | In a previous paper, the second named author obtains a decomposition of an elliptic higher Deligne-Lusztig representation into irreducible summands, which are built in the same way as Yu types using a geometric analog $κ'$ of the Weil-Heisenberg representation $κ$. In this note, we show that $κ'$ and $κ$ differs by a character $χ$. Moreover, under a mild condition on the cardinality $q$ of the residue field (for instance $q > 3$), we show that $χ$ equals the quadratic character constructed by Fintzen-Kaletha-Spice, which gives an explicit irreducible decomposition result on elliptic higher Deligne-Lusztig representations. As an application, we deduce (under the mild condition on $q$) that each unramified Yu type appears in the cohomology of higher Deligne-Lusztig varieties, and each unramified Kaletha's regular supercuspidal representation is the compact induction of a specified higher Deligne-Lusztig representation up to a sign. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_12918 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | An explicit decomposition of higher Deligne-Lsuztig representations Liu, Ben Nie, Sian Representation Theory In a previous paper, the second named author obtains a decomposition of an elliptic higher Deligne-Lusztig representation into irreducible summands, which are built in the same way as Yu types using a geometric analog $κ'$ of the Weil-Heisenberg representation $κ$. In this note, we show that $κ'$ and $κ$ differs by a character $χ$. Moreover, under a mild condition on the cardinality $q$ of the residue field (for instance $q > 3$), we show that $χ$ equals the quadratic character constructed by Fintzen-Kaletha-Spice, which gives an explicit irreducible decomposition result on elliptic higher Deligne-Lusztig representations. As an application, we deduce (under the mild condition on $q$) that each unramified Yu type appears in the cohomology of higher Deligne-Lusztig varieties, and each unramified Kaletha's regular supercuspidal representation is the compact induction of a specified higher Deligne-Lusztig representation up to a sign. |
| title | An explicit decomposition of higher Deligne-Lsuztig representations |
| topic | Representation Theory |
| url | https://arxiv.org/abs/2506.12918 |