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Criteria for discrete decomposability and admissibility in the branching problem
Abstract
In this paper, we study when the restriction of an irreducible representation of a reductive Lie group G to a reductive subgroup H is discretely decomposable. T.\ Kobayashi gave a necessary condition for discrete decomposability in terms of associated varieties. In a previous paper, we proved that the condition is also sufficient if $(G, H)$ is a symmetric pair. The purpose of this paper is to prove the sufficiency for any reductive subgroup H under some hypothesis on G (e.g., G is linear). As an application, we show that discrete decomposability is equivalent to h-admissibility when the compact factor of h is maximal in some sense.
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BibTeX
@misc{kitagawa2026criteria,
title = {{Criteria for discrete decomposability and admissibility in the branching problem}},
author = {Masatoshi Kitagawa},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.06458},
eprint = {2609.06458},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.06458},
}
RIS
TY - UNPB
TI - Criteria for discrete decomposability and admissibility in the branching problem
AU - Masatoshi Kitagawa
PY - 2026
DA - 2026/09/06
PB - arXiv
DO - 10.48550/arxiv.2609.06458
UR - https://arxiv.org/abs/2609.06458
AB - In this paper, we study when the restriction of an irreducible representation of a reductive Lie group G to a reductive subgroup H is discretely decomposable. T.\ Kobayashi gave a necessary condition for discrete decomposability in terms of associated varieties. In a previous paper, we proved that the condition is also sufficient if $(G, H)$ is a symmetric pair. The purpose of this paper is to prove the sufficiency for any reductive subgroup H under some hypothesis on G (e.g., G is linear). As an application, we show that discrete decomposability is equivalent to h-admissibility when the compact factor of h is maximal in some sense.
ER -