On the real zeros of depth 1 quasimodular forms

Bo-Hae Im; Wonwoong Lee

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arXiv · 2401.01000

On the real zeros of depth 1 quasimodular forms

Bo-Hae Im·Wonwoong Lee

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Abstract

We discuss the critical points of modular forms, or more generally the zeros of quasimodular forms of depth $1$ for $\mathrm{PSL}_2(\mathbb Z)$. In particular, we consider the derivatives of the unique weight $k$ modular forms $f_k$ with the maximal number of consecutive zero Fourier coefficients following the constant $1$. Our main results state that (1) every zero of a depth $1$ quasimodular form near the derivative of the Eisenstein series in the standard fundamental domain lies on the geodesic segment $\{z \in \mathbb H: \Re(z)=1/2\}$, and (2) more than half of zeros of $f_k$ in the standard fundamental domain lie on the geodesic segment $\{z \in \mathbb H: \Re(z)=1/2\}$ for large enough $k$ with $k\equiv 0 \pmod{12}$.

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Bo-Hae Im, Wonwoong Lee. 2024-01-02. On the real zeros of depth 1 quasimodular forms. https://arxiv.org/abs/2401.01000

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