A large sieve inequality for characters to quadratic moduli
C. C. Corrigan
TL;DR
This work proves a large sieve inequality for additive characters with moduli given by a quadratic polynomial $f$, extending known results from square moduli to general degree-two polynomials. The core is a dyadic, Farey-based reduction together with a principal estimate bounding a key quantity $K_\delta$ via a sophisticated exponential-sum analysis that uses Gauss sums and short-interval counting. The main outcome yields a bound for $\mathscr{N}_f(Q,N)$ that sharpens the trivial estimate in the range $f(Q)\ll N\ll f(Q)^2$ and confirms the conjectural behavior in $f(Q)\ll N\ll f(Q)\sqrt{Q}$, while enabling a weighted zero-density result for twists of Dirichlet $L$-functions by characters with conductors of the form $f(q)$. The paper further derives a multiplicative analogue and discusses the implications for zero distribution and mean values of Dirichlet polynomials, including conditional improvements under conjectures for higher moments.
Abstract
In this article, we establish a large sieve inequality for additive characters to moduli in the range of appropriate integer polynomials of degree two. As an application, we derive a weighted zero-density estimate for twists of $L$-functions associated to multiplicative characters with conductor of this form.
