One-level density of zeros of $Γ_1(q)$ $L$-functions
Arijit Paul
TL;DR
The paper studies the one-level density of zeros for the large unitary family of $\Gamma_1(q)$ $L$-functions associated to holomorphic cusp forms. Using the explicit formula and a delicate off-diagonal analysis, it extends the admissible Fourier support to $(-\frac{8}{3},\frac{8}{3})$ under GRH and confirms the Katz–Sarnak unitary prediction for this family, i.e., $D_{\mathcal{F}}(\varphi) = \int_{-\infty}^{\infty} \varphi(x)\,dx + o(1)$. As an application, the work yields a lower bound of $\frac{5}{8}$ (62.5%) for the proportion of non-vanishing central values, the best known for any unitary family. The results indicate that the underlying GL2 structure and off-diagonal arithmetic play a decisive role in extending spectral-density support, more so than the symmetry group alone.
Abstract
We study the one-level density of zeros for a family of $Γ_1(q)$ $L$-functions. Assuming GRH, we are able to extend the support of the Fourier transform of the test function to $\left(-\frac{8}{3},\frac{8}{3}\right)$ and verify the Katz-Sarnak prediction for our unitary family. As an application, we obtain that the proportion of forms in the family with non-vanishing at the central point is at least $62.5\%$, assuming GRH. This is the highest non-vanishing proportion for any family associated with a unitary group. Moreover, this result indicates that the structural properties of $L$-functions play a more important role in extending the support than the associated symmetry group.
