REVIEW
Zero density in short strips and short-interval bounds toward Hypothesis S
Number Theory · Submitted 11 Oct 2026
Pith's verdict: Clean technical extension of Guth–Maynard to short strips; honest about its limits, but the advance is narrow.
T0 · AI review
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Referee report
The paper
The paper claims
Improved zero-density estimates for the Riemann zeta function in short vertical strips, and applications to prime exponential sums with phase α n^β.
The reading
What carries the argument
The large-value estimate of Guth and Maynard for Dirichlet polynomials and the Type II zero integral argument of Maynard and Pratt, adapted to short strips via a detector function (a mollified Dirichlet polynomial combined with a gamma factor integral). This detector separates zeros into Type I (controlled by the large-value estimate) and Type II (controlled by moment bounds). The short-interval fourth moment of the Riemann zeta function (cited from Heath-Brown and Iwaniec) supplies the moment input for Type II. For the automorphic applications, the earlier Ye–Zhang density bounds for cusp forms are used instead of any new short-strip density estimate.
Extended reading notes
Core claim
The paper establishes a general moment-to-density theorem (Theorem 1.1) for globally tempered automorphic L-functions on short strips. Applied to the Riemann zeta function using the known short-interval fourth moment (Heath-Brown, Iwaniec), it obtains N_ζ(σ; T, T+T^a) ≪ $T^{{a B(σ)+ε}}$ with B(σ)=15(1-σ)/(3+5σ) for 7/10 ≤ σ ≤ 4/5 and 2/3 ≤ a ≤ 1. This improves the earlier exponent of Ye–Zhang on that σ-range and localizes the Guth–Maynard full-interval bound to intervals of length T^a. The paper then derives explicit power savings for smoothed prime-power sums with phase exp(2π i α n^β) for fixed α≠0, 0<β<1, using the explicit formula. The minimal interval length thresholds for obtaining a power saving are 2/3 (for zeta), 3/4 (for GL(2) cusp forms twisted by a real character), and 5/6 (for self-dual GL(3) Maass cusp forms). Uniform frequency dependence for mα with 1 ≤ m ≤ K^R is also given.
Load-bearing premise
The short-interval fourth moment of the Riemann zeta function, ∫$_T^{{T+T^a}}$ |ζ(1/2+it)|^4 dt ≪ $T^{{a+η}}$ for a ≥ 2/3, is cited from Heath-Brown and Iwaniec and not proved in the paper; if this bound were false or required a larger minimal a, the main zero-density improvement for zeta would be lost.
Editorial extensions
If this is right
- For the Riemann zeta function, the zero-density exponent on 7/10 < σ < 4/5 is strictly improved, narrowing the gap toward the density hypothesis.
- The smoothed prime-power sum S_ζ(mα, β; K, K^δ) admits a power saving over the interval length K^δ whenever δ > d(β), with d(β) as low as 2/3 (at β=8/9), and the saving is effective uniformly for m up to K^R.
- For twists of self-dual GL(2) cusp forms by a real primitive character, a power saving holds for β < 2/3 with minimal interval threshold 3/4, without assuming the Ramanujan conjecture.
- For self-dual GL(3) Maass cusp forms, a power saving holds for β < 1/2 with minimal interval threshold 5/6, also without Ramanujan.
Reading between the lines
- If improved short-interval moments for cusp-form L-functions become available (e.g., via progress on the Ramanujan conjecture or subconvexity), the same framework could yield new zero-density bounds for those L-functions and extend the power-saving range.
- The fact that the improvement is limited to the strip 7/10 < σ < 4/5 suggests that a different mechanism would be needed to push beyond these endpoints, perhaps requiring new large-value estimates or moment inputs.
- The technique of using the explicit formula to convert short-strip zero-density estimates into bounds on exponential sums over primes is general and could be applied to other L-functions once corresponding density estimates are obtained.
Original abstract
We deduce zero-density estimates in short vertical strips from short-interval moments of globally tempered automorphic $L$-functions, by adapting the large-value estimate of Guth and Maynard and the Type II zero argument of Maynard and Pratt to the framework of Ye and Zhang. For the Riemann zeta function, we obtain $N_\zeta(\sigma;T,T+T^a)\ll T^{15a(1-\sigma)/(3+5\sigma)+\varepsilon}$ for $2/3\le a\le1$ and $7/10\le\sigma\le4/5$, improving Ye--Zhang's exponent in the interior of this range. Combining the localized density bound with the recent quasi-Riemann theorems, we estimate smoothed prime-power sums with phase $\exp(2\pi i\alpha n^\beta)$ on intervals of length $K^\delta$. For $0<\beta<13/20$, we obtain a power saving whenever $\max\{17/30,1-\beta\}<\delta<1$; in particular the square-root phase admits every $\delta>17/30$. A revised transform estimate retains both the stationary spread and the Fourier width $K/L$. For example, the bound at $\beta=1/2$, $\delta=3/5$ is $K^{15/26+\varepsilon}$, uniformly for frequencies $m\alpha$ with $1\le m\le K^{1/10}$. We also retain power savings for certain self-dual $GL(2)$ twists and self-dual $GL(3)$ cusp forms, without assuming Ramanujan. All three applications have explicit frequency dependence.
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 deduce zero-density estimates in short vertical strips from short-interval moments of globally tempered automorphic $L$-functions, by adapting the large-value estimate of Guth and Maynard and the Type II zero argument of Maynard and Pratt to the framework of Ye and Zhang. For the Riemann zeta function, we obtain $N_\zeta(\sigma;T,T+T^a)\ll T^{15a(1-\sigma)/(3+5\sigma)+\varepsilon}$ for $2/3\le a\le1$ and $7/10\le\sigma\le4/5$. This improves Ye--Zhang's exponent for $7/10<\sigma<4/5$ and localizes Guth--Maynard's density bound to short intervals of ordinates. Through the explicit formula, we apply these estimates to smoothed prime-power sums with phase $\exp(2\pi i\alpha n^\beta)$, for fixed $\alpha\ne0$ and $0<\beta<1$. We obtain explicit power savings over the interval length $K^\delta$ for zeta and, using the earlier cusp-form density bounds, for certain real primitive character twists of self-dual $GL(2)$ cusp forms and self-dual $GL(3)$ Maass cusp forms. The smallest interval thresholds in these three applications are $2/3$, $3/4$, and $5/6$, respectively. We give explicit frequency dependence when $\alpha$ is replaced by $m\alpha$, uniformly for $1\le m\le K^R$ with any fixed $R>0$. The cusp-form applications do not require the Ramanujan conjecture.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We deduce zero-density estimates in short vertical strips from short-interval moments of globally tempered automorphic $L$-functions, by adapting the large-value estimate of Guth and Maynard and the Type II zero argument of Maynard and Pratt to the framework of Ye and Zhang. | contribution 0.59 | 0.94 | 0.33 | asserted 1.00 |
| s1 | For the Riemann zeta function, we obtain $N_\zeta(\sigma;T,T+T^a)\ll T^{15a(1-\sigma)/(3+5\sigma)+\varepsilon}$ for $2/3\le a\le1$ and $7/10\le\sigma\le4/5$. | result 1.00 | 0.94 | 0.38 | asserted 1.00 |
| s2 | This improves Ye--Zhang's exponent for $7/10<\sigma<4/5$ and localizes Guth--Maynard's density bound to short intervals of ordinates. | interpretation 0.86 | 0.90 | 0.30 | asserted 1.00 |
| s3 | Through the explicit formula, we apply these estimates to smoothed prime-power sums with phase $\exp(2\pi i\alpha n^\beta)$, for fixed $\alpha\ne0$ and $0<\beta<1$. | method 0.72 | 0.92 | 0.06 | asserted 1.00 |
| s4 | We obtain explicit power savings over the interval length $K^\delta$ for zeta and, using the earlier cusp-form density bounds, for certain real primitive character twists of self-dual $GL(2)$ cusp forms and self-dual $GL(3)$ Maass cusp forms. | result 0.96 | 0.95 | 0.19 | asserted 1.00 |
| s5 | The smallest interval thresholds in these three applications are $2/3$, $3/4$, and $5/6$, respectively. | result 1.00 | 0.90 | 0.11 | asserted 1.00 |
| s6 | We give explicit frequency dependence when $\alpha$ is replaced by $m\alpha$, uniformly for $1\le m\le K^R$ with any fixed $R>0$. | result 0.72 | 0.93 | 0.04 | asserted 1.00 |
| s7 | The cusp-form applications do not require the Ramanujan conjecture. | result 0.68 | 0.63 | 0.04 | asserted 1.00 |
What was examined, and what was not
- arXiv listing abstract v1
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References
Discussion
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