Generic twisted $T$-adic exponential sums of binomials.

link: http://arxiv.org/abs/0911.5182
Abstract

The twisted $T$-adic exponential sum associated to $x^{d}+\lambda x$ is
studied. If $\lambda\neq0,$ then an explicit arithmetic polygon is proved to be
the Newton polygon of the twisted $C$-function of the T-adic exponential sum.
It gives the Newton polygons of the $L$-functions of twisted $p$-power order
exponential sums.