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On Drinfeld modular forms of higher rank V: The behavior of distinguished forms on the fundamental domain

Number Theory 2020-09-04 v1

Abstract

\begin{document} \begin This paper continues work of the earlier articles with the same title. For two classes of modular forms ff: \begin{itemize} \item para-Eisenstein series αk\alpha_{k} and \item coefficient forms ak{}_a \ell_{k}, where kNk \in \mathbb{N} and aa is a non-constant element of Fq[T]\mathbb{F}_{q}[T], \end{itemize} the growth behavior on the fundamental domain and the zero loci Ω(f)\Omega(f) as well as their images BT(f)\mathcal{BT}(f) in the Bruhat-Tits building BT\mathcal{BT} are studied. We obtain a complete description for f=αkf = \alpha_{k} and for those of the forms ak{}_{a}\ell_{k} where kdegak \leq \deg a. It turns out that in these cases, αk\alpha_{k} and ak{}_{a}\ell_{k} are strongly related, e.g., BT(ak)=BT(αk)\mathcal{BT}({}_{a}\ell_{k}) = \mathcal{BT}(\alpha_{k}), and that BT(αk)\mathcal{BT}(\alpha_{k}) is the set of Q\mathbb{Q}-points of a full subcomplex of BT\mathcal{BT} with nice properties. As a case study, we present in detail the outcome for the forms α2\alpha_{2} in rank 3. \end{abstract} \maketitle \end{document}

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Cite

@article{arxiv.2009.01622,
  title  = {On Drinfeld modular forms of higher rank V: The behavior of distinguished forms on the fundamental domain},
  author = {Ernst-Ulrich Gekeler},
  journal= {arXiv preprint arXiv:2009.01622},
  year   = {2020}
}

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34 pages