Abstract
Let be a quadratic extension of nonarchimedean locally compact fields of residual characteristic and let denote its nontrivial automorphism. Let be an algebraically closed field of characteristic different from . To any cuspidal representation of , with coefficients in , such that (such a representation is said to be -selfdual) we associate a quadratic extension , where is a tamely ramified extension of and is a tamely ramified extension of , together with a quadratic character of . When is supercuspidal, we give a necessary and sufficient condition, in terms of these data, for to be -distinguished. When the characteristic of is not , denoting by the nontrivial -character of trivial on -norms, we prove that any -selfdual supercuspidal -representation is either distinguished or -distinguished, but not both. In the modular case, that is when , we give examples of -selfdual cuspidal nonsupercuspidal representations which are not distinguished nor -distinguished. In the particular case where is the field of complex numbers, in which case all cuspidal representations are supercuspidal, this gives a complete distinction criterion for arbitrary complex cuspidal representations, as well as a purely local proof, for cuspidal representations, of the dichotomy and disjunction theorem due to Kable and Anandavardhanan, Kable and Tandon, when .
Citation
Vincent Sécherre. "Supercuspidal representations of ${\rm GL}_n({\rm F})$ distinguished by a Galois involution." Algebra Number Theory 13 (7) 1677 - 1733, 2019. https://doi.org/10.2140/ant.2019.13.1677
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