Matchings of theta lifts associated to Non-trivial Automorphic Characters of Odd Orthogonal Groups

Abstract

This work is largely inspired by the 2003 Ph.D. thesis \cite{snitz} of Kobi Snitz. In his thesis, Snitz constructed two irreducible, automorphic, cuspidal representations $ \pi $ and $ \pi' $ of the metaplectic group $ G\left ( \mathbb A \right ) = \widetilde{ SL }_{ 2 } \left ( \mathbb A \right ) $ where each representation is obtained from a different global theta lifts of certain non-trivial automorphic characters $ \xi $ and $ \xi' $ of the orthogonal groups $ H_{ \mathbb A } = O \left ( q, V \right ) \left ( \mathbb A \right ) $ and $ H_{ \mathbb A } '= O \left ( q', V' \right ) \left ( \mathbb A \right ) $, respectively, where $ \mathbb A = \mathbb A_{ \mathbb F } $ is the adele ring of a number field $ \mathbb F $. Snitz shows that for certain matching data of quadratic spaces and automorphic quadratic characters, that these two representations of $ G \left ( \mathbb A \right ) $ are isomorphic, i.e. $ \pi\cong\pi'$. The goal of this work is to reformulate and generalize Snitz's work to higher rank groups. Namely we wish to determine for which admissible data $\left ( \left ( q, V \right ) ,\xi , \left ( q', V' \right ),\xi'\right )$ satisfying certain local necessary conditions could an isomorphism possibly exist between two global theta lifts $ \pi $ and $ \pi'$ with respect to two reductive dual pairs $ H_{ \mathbb A } \times G_{ \mathbb A } $ and $ H'_{ \mathbb A } \times G_{ \mathbb A } $ and two non-trivial automorphic quadratic characters $ \xi $ and $ \xi'$ of the orthogonal groups $ H_{ \mathbb A } = O \left ( q, V \right ) \left ( \mathbb A \right ) $ and $ H_{ \mathbb A } '= O \left ( q', V'\right ) \left ( \mathbb A \right ) $, respectively and the group $ G $ which is the symplectic or the metaplectic group.