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| Format: | Preprint |
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2022
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| Online Access: | https://arxiv.org/abs/2201.11293 |
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| _version_ | 1866912805270061056 |
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| author | Harris, Benjamin Oshima, Yoshiki |
| author_facet | Harris, Benjamin Oshima, Yoshiki |
| contents | Let $G$ be a real linear reductive group and let $H$ be a unimodular, locally algebraic subgroup. Let $\operatorname{supp} L^2(G/H)$ be the set of irreducible unitary representations of $G$ contributing to the decomposition of $L^2(G/H)$, namely the support of the Plancherel measure. In this paper, we will relate $\operatorname{supp} L^2(G/H)$ with the image of moment map from the cotangent bundle $T^*(G/H)\to \mathfrak{g}^*$. For the homogeneous space $X=G/H$, we attach a complex Levi subgroup $L_X$ of the complexification of $G$ and we show that in some sense "most" of representations in $\operatorname{supp} L^2(G/H)$ are obtained as quantizations of coadjoint orbits $\mathcal{O}$ such that $\mathcal{O}\simeq G/L$ and that the complexification of $L$ is conjugate to $L_X$. Moreover, the union of such coadjoint orbits $\mathcal{O}$ coincides asymptotically with the moment map image. As a corollary, we show that $L^2(G/H)$ has a discrete series if the moment map image contains a nonempty subset of elliptic elements. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2201_11293 |
| institution | arXiv |
| publishDate | 2022 |
| record_format | arxiv |
| spellingShingle | On the asymptotic support of Plancherel measures for homogeneous spaces Harris, Benjamin Oshima, Yoshiki Representation Theory Let $G$ be a real linear reductive group and let $H$ be a unimodular, locally algebraic subgroup. Let $\operatorname{supp} L^2(G/H)$ be the set of irreducible unitary representations of $G$ contributing to the decomposition of $L^2(G/H)$, namely the support of the Plancherel measure. In this paper, we will relate $\operatorname{supp} L^2(G/H)$ with the image of moment map from the cotangent bundle $T^*(G/H)\to \mathfrak{g}^*$. For the homogeneous space $X=G/H$, we attach a complex Levi subgroup $L_X$ of the complexification of $G$ and we show that in some sense "most" of representations in $\operatorname{supp} L^2(G/H)$ are obtained as quantizations of coadjoint orbits $\mathcal{O}$ such that $\mathcal{O}\simeq G/L$ and that the complexification of $L$ is conjugate to $L_X$. Moreover, the union of such coadjoint orbits $\mathcal{O}$ coincides asymptotically with the moment map image. As a corollary, we show that $L^2(G/H)$ has a discrete series if the moment map image contains a nonempty subset of elliptic elements. |
| title | On the asymptotic support of Plancherel measures for homogeneous spaces |
| topic | Representation Theory |
| url | https://arxiv.org/abs/2201.11293 |