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The following peculiar p-adic integrals have arisen in my work, and I would be interested if anyone can see how to tackle them.

Let $F$ be a $p$-adic field, $\mathfrak{o}$ its ring of integers, $\mathfrak{o}^{\times}$ the units in $\mathfrak{o}$, and $\varpi$ a fixed uniformizer in $F$. Let $\psi$ be an additive character of $F$, trivial on $\mathfrak{p}$, but nontrivial on $\mathfrak{o}$. Let $\gamma_{\psi}$ be the Weil index associated to $\psi$.

Integral 1) Suppose that $p = 2$. Let $n$ be a non-negative integer. Compute $$\int_{\mathfrak{o}^{\times}} \gamma_{\psi}(\varpi^n z) d^{\times} z$$

Integral 2) Suppose that $p \neq 2$ and let $n$ be a non-negative integer. Compute $$\int_{\mathfrak{o}^{\times}} \gamma_{\psi}(\varpi^n z) \tau(z) d^{\times} z,$$ where $\tau$ is a (possibly trivial) character of $\mathfrak{o}^{\times}$ that is trivial on $1 + \mathfrak{p}$.

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  • $\begingroup$ These computations should be straightforward, using the explicit formulas of Ranga Rao. See the appendix of "On some explicit formulas in the theory of the Weil representation" in Pacific J. of Math., Vol. 157, No. 2, 1993. $\endgroup$
    – Marty
    Commented Nov 16, 2014 at 7:14
  • $\begingroup$ Dear Marty: For $p = 2$, Ranga Rao only gives explicit formulas in the case where $F = \mathbb{Q}_2$. I would very much prefer to not assume this on the base field. Therefore I was hoping that the general properties of Weil indices (from Ranga Rao) would allow me to simplify/compute these integrals (in the case $p = 2$ and $p \neq 2$). $\endgroup$ Commented Nov 16, 2014 at 12:20

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