Abstract
We prove explicit rationality-results for Asai- $L$-functions, $L^S(s,\Pi’,{\rm As}^\pm)$, and Rankin-Selberg $L$-functions, $L^S(s,\Pi\times\Pi’)$, over arbitrary CM-fields $F$, relating critical values to explicit powers of $(2\pi i)$. Besides determining the contribution of archimedean zeta-integrals to our formulas as concrete powers of $(2\pi i)$, it is one of the crucial advantages of our refined approach, that it applies to very general non-cuspidal isobaric automorphic representations $\Pi’$ of ${\rm GL}_n(\mathbb A_F)$. As a major application, this enables us to establish a certain algebraic version of the Gan–Gross–Prasad conjecture, as refined by N.\ Harris, for totally definite unitary groups: This generalizes a deep result of Zhang and complements totally recent progress of Beuzard-Plessis. As another application we obtain a generalization of an important result of Harder–Raghuram on quotients of consecutive critical values, proved by them for totally real fields, and achieved here for arbitrary CM-fields $F$ and pairs $(\Pi,\Pi’)$ of relative rank one.
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URL
https://arxiv.org/abs/1705.07701