Character sums over co-dimension one sub-lattices in finite field extensions

Abstract

We obtain nontrivial bounds for multiplicative character sums over codimension-one sublattices of finite field extensions ${\mathbb{F}}_{p^d}$. This extends earlier results of Davenport--Lewis and Chang from full-dimensional settings to the codimension-one setting. As an application, we establish cancellation in character sums over binary cubic forms for intervals of length $p^{3/8+\epsilon }$. Our approach combines Burgess-type amplification technique, represesentation of character sum using multiplicative energy and it's estimates to prove the result.

10 pages