Uniqueness of Bessel models for $\mathrm{GSpin}$ groups
Pan Yan
TL;DR
This work proves a multiplicity-one result for general Bessel models on $\mathrm{GSpin}$ groups over local fields of characteristic zero, by reducing to the spherical case. The authors construct a local zeta integral $\mathcal{Z}_{\mu}$ associated with a Bessel functional and analyze induced representations $\pi_s'$ of $\mathrm{GSpin}(V')$ to realize $\mathcal{Z}_{\mu}$ in a spherical model, showing nonvanishing and absolute convergence in a suitable region. The main contribution is proving $\dim_{\mathbb{C}} \operatorname{Hom}_{H}(\pi \otimes \pi_0, \xi) \le 1$, unifying Whittaker and spherical uniqueness within a single Bessel-family framework and aligning with local Gan–Gross–Prasad expectations for $\mathrm{GSpin}$ groups. This result paves the way for Euler product factorization of global Rankin–Selberg integrals on $\mathrm{GSpin}$ and provides a foundational step toward the local Gan–Gross–Prasad conjecture in this setting, with implications for both nonarchimedean and archimedean fields.
Abstract
We prove the uniqueness of general Bessel models for $\mathrm{GSpin}$ groups over a local field of characteristic zero. The proof is to reduce it to the spherical case, which has been proved by Emory and Takeda in the non-archimedean case and by Emory, Kim, and Maiti in the archimedean case.
