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Reducibility of the Principal Series for Sp~2(F) over a p-adic Field

  Published:2010-05-20
 Printed: Aug 2010
  • Christian Zorn,
    Mathematics Department, The Ohio State University, Columbus, OH, USA
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Abstract

Let $G_n=\mathrm{Sp}_n(F)$ be the rank $n$ symplectic group with entries in a nondyadic $p$-adic field $F$. We further let $\widetilde{G}_n$ be the metaplectic extension of $G_n$ by $\mathbb{C}^{1}=\{z\in\mathbb{C}^{\times} \mid |z|=1\}$ defined using the Leray cocycle. In this paper, we aim to demonstrate the complete list of reducibility points of the genuine principal series of ${\widetilde{G}_2}$. In most cases, we will use some techniques developed by Tadić that analyze the Jacquet modules with respect to all of the parabolics containing a fixed Borel. The exceptional cases involve representations induced from unitary characters $\chi$ with $\chi^2=1$. Because such representations $\pi$ are unitary, to show the irreducibility of $\pi$, it suffices to show that $\dim_{\mathbb{C}}\mathrm{Hom}_{{\widetilde{G}}}(\pi,\pi)=1$. We will accomplish this by examining the poles of certain intertwining operators associated to simple roots. Then some results of Shahidi and Ban decompose arbitrary intertwining operators into a composition of operators corresponding to the simple roots of ${\widetilde{G}_2}$. We will then be able to show that all such operators have poles at principal series representations induced from quadratic characters and therefore such operators do not extend to operators in $\mathrm{Hom}_{{\widetilde{G}_2}}(\pi,\pi)$ for the $\pi$ in question.
MSC Classifications: 22E50, 11F70 show english descriptions Representations of Lie and linear algebraic groups over local fields [See also 20G05]
Representation-theoretic methods; automorphic representations over local and global fields
22E50 - Representations of Lie and linear algebraic groups over local fields [See also 20G05]
11F70 - Representation-theoretic methods; automorphic representations over local and global fields
 

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