The subconvexity bound for standard L-function in level aspect
Yueke Hu, Paul Nelson
TL;DR
This work establishes a new subconvexity bound for the standard L-function L(π, 1/2) of a unitary cuspidal automorphic representation π on GL_n over Q in the level aspect, allowing a varying finite ramification set S under a uniform archimedean growth condition. The authors develop an S-adic framework combining localized Whittaker analysis, p-adic test vectors, and Archimedean Eisenstein-growth control, introducing an auxiliary parameter R to balance disparate contributions and a denominator-control mechanism for finite places. The main result yields |L(π, 1/2)| ≤ C_1 (T^n)^{1/4 - δ} C(π^S)^{1/2} for some δ > 0 and all twists by square-conductor characters, with a corresponding corollary for L(π ⊗ χ, 1/2 + it) and conductor N^2. This advances higher-rank subconvexity in the horizontal variation (varying ramification sets) by unifying previous archimedean/subconvex techniques with new S-adic localization and Rankin–Selberg analyses, providing a framework potentially adaptable to broader level-aspect problems in automorphic L-functions.
Abstract
In this paper we prove a new subconvexity result for the standard L-function of a unitary cuspidal automorphic representation $π$ of $\text{GL}_n$, where the finite set of places $S$ with large conductors is allowed to vary, provided that the local parameters at every place in $S$ satisfy certain uniform growth condition.
