The exotic inverted Kloosterman sum

Lei Fu, Daqing Wan

Let $B$ be a product of finitely many finite fields containing ${\mathbb{F}}_q$, $\psi :{\mathbb{F}}_q\to {\overline{\mathbb{Q}}}_{\ell }^{\ast }$ a nontrivial additive character, and $χ: B^*\to \overli…