REVIEW
Bounding The Number of Zeros Near the Central Point in Families of Cuspidal Newforms
Number Theory · Submitted 15 Aug 2026 · 25 references
Pith's verdict: New counting bound for low-lying zeros (N^{7/8} log N) is sound; positive proportion theorem rests on an unverified moment inequality the abstract overstates.
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Referee report
The paper
The paper claims
Under GRH, a positive proportion of even cuspidal newforms of prime level has a zero in a prescribed window about the central point whenever a stated centered-moment inequality holds.
The reading
What carries the argument
The machinery is the asymptotic theory of the centered moments of the one-level density: Theorem 1.8 (taken from [Coh+26]) states that under GRH and a Fourier-support condition $\operatorname{supp}(\hat{\varphi}) \subset (-\sigma/n,\sigma/n)$ with $1\le \sigma\le 2$, the $n$-th centered moment over the family converges to $(n-1)!!\,(V_\varphi^2)^{n/2} \pm S(n,a;\varphi)$, where $S(n,a;\varphi)$ is an explicit iterated integral of $\hat{\varphi}$ and $\varphi$. Two test functions carry the argument. The first is the sign-changing function $\varphi_\omega(x) = (1-(x/\omega)^2)\,\hat{g}(x)$, built from an auxiliary even function $h$ by rescaling and convolution; it is nonnegative exactly on $[-\omega,\omega]$ and nonpositive outside, so its positive contribution to the one-level statistic can only come from zeros inside the window, and this sign pattern converts an odd moment inequality into a statement about how many forms have zeros there. The second is an auxiliary nonnegative Schwartz function (Lemma 3.1) that is bounded below on $[-\omega,\omega]$ and has Fourier support in $(-1/n,1/n)$; it makes the $2n$-th moment of the zero count $R_f(\omega)$ uniformly bounded. The final step is Cauchy–Schwarz: the moment gap $\Delta = S(n,a;\varphi_\omega)-(-\mu)^n > 0$ bounds the average of the nonnegative quantities $\Pi_f = (X_f-\mu)^n-(-\mu)^n$ from below, the second moment of $\Pi_f$ is bounded by the same constant $C$, and $a_{\omega,N}/|F_N| \ge \Delta^2/(4C)$ follows.
Extended reading notes
Core claim
The paper's central claim is a count rather than an existence: the number $a_{\omega,N}$ of even newforms of level $N$ whose $L$-function has at least one normalized zero in $(-\omega,\omega)$ obeys the lower bounds of Theorems 1.15 and 1.18. Theorem 1.15 says that if $\omega$ satisfies $-\bigl(\hat{\varphi}(0)+\tfrac12\int \hat{\varphi}(y)\,dy\bigr) < S(1,\sigma;\varphi_\omega)$, then along a sequence of prime levels $a_{\omega,N} \gg N^{7/8}\log N$. Theorem 1.18 says that if for some odd $n\ge 3$ the strict inequality $(-\mu)^n < S(n,a;\varphi_\omega)$ holds, with $\mu$ the limiting mean of the one-level density, then $a_{\omega,N}/|F_N|$ stays bounded away from zero: a positive proportion of the family carries a zero in the window. From this the paper derives that some exact integer $r\ge 1$ occurs as the number of zeros in the window on a positive proportion of forms, that forms with at least $r$ zeros have density at most $C_1/r^{2n}$, and that a positive proportion of forms have between one and $r_0-1$ zeros. The unifying mechanism is that the sign-changing test function $\varphi_\omega$ makes the odd centered-moment excess detectable only through forms with zeros inside the window, while a uniformly bounded even moment of the zero count $R_f(\omega)$ prevents that excess from being concentrated on a negligible set of forms.
Load-bearing premise
The load-bearing premise is that some odd moment order $n\ge 3$ and some window $\omega$ satisfy the strict inequality $(-\mu)^n < S(n,a;\varphi_\omega)$, where $\mu$ is the family's average one-level density and $S(n,a;\varphi_\omega)$ is a computable 'moment-excess' integral; the paper assumes this inequality holds without verifying it for any explicit $n$ or $\omega$ or supplying numerical evidence, so if it fails for every odd $n\ge 3$ the positive-proportion theorem has no instances (and GRH is assumed throughout).
Editorial extensions
If this is right
- Under the first-moment condition, the number of forms with a zero in the window satisfies $a_{\omega,N} \gg N^{7/8}\log N$ infinitely often in prime level $N$, so the phenomenon already goes well beyond 'at least one form'.
- For any window satisfying the odd-moment condition, a fixed positive fraction $\Delta^2/(4C)$ of the family has at least one zero in the window, making such zeros typical rather than exceptional.
- The distribution of the number of zeros in the window has atoms: some positive integer $r$ occurs as the exact zero count on a positive proportion of forms (Corollary 1.20).
- Forms with unusually many zeros in the window are polynomially rare: the density of forms with at least $r$ zeros is at most $C_1/r^{2n}$, and a positive proportion of forms carry between 1 and $r_0-1$ zeros (Corollaries 3.3 and 3.4).
- Because $|F_N| \asymp N$ for fixed weight, the positive-proportion statement is a linear lower bound $a_{\omega,N} \gg_{\omega,n,k} N$ on the number of forms with a zero (Corollary 1.19).
Reading between the lines
- If the moment-excess inequality $(-\mu)^n < S(n,a;\varphi_\omega)$ were verified numerically, say for the explicit choice $h(u)=\cos(\pi u/2)$ at $\omega\approx 0.21864$ and small odd $n$, Theorem 1.18 would immediately yield an explicit positive proportion; the paper itself does not perform that verification, so the constant is not yet explicit.
- The same template—an odd moment excess detected by a sign-changing test function, converted by a bounded even moment of the zero count into a positive proportion—should transfer to other orthogonal families such as quadratic twists or Dirichlet $L$-functions wherever centered-moment asymptotics with an $S$-term are available, so the phenomenon is likely generic rather than special to prime-level n
- Letting the window shrink slowly with the level ($\omega_N \to 0$) is the natural next test: if the moment excess survives in that regime, the methods could begin to say something about how many forms vanish exactly at the central point, connecting through modularity and the Birch–Swinnerton-Dyer conjecture to the distribution of analytic ranks in the family.
Original abstract
We study low-lying zeros in families of even holomorphic cuspidal newforms of fixed weight and prime level, with particular emphasis on the number of forms having a zero in a prescribed normalized window about the central point and on the distribution of the number of such zeros among the forms. We quantify the number of forms having at least one zero in the window and study the distribution of the number of zeros in that window among the forms. Assuming the Generalized Riemann Hypothesis, we obtain new lower bounds for the number of forms having a low-lying zero. We first prove that, along an infinite sequence of prime levels $N$, the number of such forms is $\gg N^{7/8}\log N$. We then use higher centered moments and an appropriate test function to show that a positive proportion of the family has a zero in a prescribed window. Finally, we obtain polynomial upper-tail bounds for the number of zeros occurring there and show that a positive proportion of forms have a bounded, nonzero number of low-lying zeros.
The compiled record
The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
The abstract, sentence by sentence
We study low-lying zeros in families of even holomorphic cuspidal newforms of fixed weight and prime level, with particular emphasis on the number of forms having a zero in a prescribed normalized window about the central point and on the distribution of the number of such zeros among the forms. We quantify the number of forms having at least one zero in the window and study the distribution of the number of zeros in that window among the forms. Assuming the Generalized Riemann Hypothesis, we obtain new lower bounds for the number of forms having a low-lying zero. We first prove that, along an infinite sequence of prime levels $N$, the number of such forms is $\gg N^{7/8}\log N$. We then use higher centered moments and an appropriate test function to show that a positive proportion of the family has a zero in a prescribed window. Finally, we obtain polynomial upper-tail bounds for the number of zeros occurring there and show that a positive proportion of forms have a bounded, nonzero number of low-lying zeros.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We study low-lying zeros in families of even holomorphic cuspidal newforms of fixed weight and prime level, with particular emphasis on the number of forms having a zero in a prescribed normalized window about the central point and on the distribution of the number of such zeros among the forms. | contribution 0.91 | 0.90 | 0.09 | asserted 0.81 |
| s1 | We quantify the number of forms having at least one zero in the window and study the distribution of the number of zeros in that window among the forms. | contribution 0.98 | 0.94 | 0.09 | asserted 0.99 |
| s2 | Assuming the Generalized Riemann Hypothesis, we obtain new lower bounds for the number of forms having a low-lying zero. | result 0.80 | 0.93 | 0.22 | asserted 0.99 |
| s3 | We first prove that, along an infinite sequence of prime levels $N$, the number of such forms is $\gg N^{7/8}\log N$. | result 0.99 | 0.95 | 0.22 | asserted 1.00 |
| s4 | We then use higher centered moments and an appropriate test function to show that a positive proportion of the family has a zero in a prescribed window. | method 0.86 | 0.95 | 0.14 | asserted 1.00 |
| s5 | Finally, we obtain polynomial upper-tail bounds for the number of zeros occurring there and show that a positive proportion of forms have a bounded, nonzero number of low-lying zeros. | result 0.98 | 0.96 | 0.34 | asserted 1.00 |
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References
Discussion
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