GL(2) Weyl bound via a multiplicative character delta method

Abstract

We use a trivial delta method with multiplicative characters for congruence detection to prove the Weyl bound for GL(2) in the [Formula: see text]-aspect for a holomorphic or Hecke–Maass cusp form of arbitrary level and nebentypus. This parallels the work of Aggarwal [2] in 2018, with the difference being the multiplicative character has a more natural connection to the twisted [Formula: see text]-function. This provides another viewpoint to understand and explore the trivial and other delta methods.