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REAL ZEROS OF L-FUNCTION DERIVATIVES: DENSITY-ONE ASYMPTOTICS IN ARITHMETIC FAMILIES

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Abstract

We study real zeros of the derivative of an uncompleted L-function on [1/2, 1]. The limiting stationary process has covariance sech2((t− s)/2) after the change of variables σ = 1/2+e^−t. Its nonzero-level Rice intensity gives the constant e^−1/2/(π√2) for quadratic Dirichlet characters, a specified family of quadratic Hecke characters over Q(i), and the unweighted level-one holomorphic family; the resulting density-one asymptotics are unconditional. For a fixed holomorphic modular form and its quadratic twists, and for non-Galois cubic Artin L- functions, we obtain the same constant under the respective family GRH. The real cyclic cubic augmentation instead has constant 1/(π√2). In these three GRH families a uniform quantile estimate controls all three counts: distinct real zeros, zeros with multiplicity, and strict sign changes. For an individual complex cubic character, the derivative has o(log log q) real zeros in density under cubic-character GRH. We also prove a uniform mean asymptotic and exponential concentration for the random Euler model.

Introduction and statements

For a real entire LL-function LL, write RLdistR_L^{\mathrm{dist}} and RLmultR_L^{\mathrm{mult}} for the number of zeros of L′L' on the closed real interval [1/2,1][1/2,1], without and with complex-analytic multiplicity. Write SLS_L for the number of strict sign changes of L′L' on (1/2,1)(1/2,1). All derivatives in this paper are derivatives of the uncompleted function. These conventions matter at the central point and for families with root number −1-1.

The phrase “in density” always refers to the original family measure. Thus RL/HL→cR_L/H_L \to c in density means that, for every fixed η>0\eta> 0, the proportion with ∣RL/HL−c∣>η\lvert R_L/H_L - c\rvert> \eta tends to zero. This does not assert an asymptotic for every member, or an asymptotic for the family mean of the unbounded count.

Our constants are

cBM=e−1/2π2,c(m,v)=e−m2/(2v)π2(v>0).(1)c_{\mathrm{BM}} = \frac{e^{-1/2}}{\pi\sqrt{2}}, \qquad c(m,v) = \frac{e^{-m^{2}/(2v)}}{\pi\sqrt{2}} \quad(v>0). \tag*{(1)}

The parameters mm and vv are, respectively, the weighted mean of the prime-square logarithmic coefficient and the weighted variance of the prime coefficient. They are defined precisely in the Euler-model section. The variance of the derivative of a stationary Gaussian process with covariance sech⁡2(t/2)\operatorname{sech}^{2}(t/2) is 1/21/2. Its crossings of the level −m/v-m/\sqrt{v} have intensity c(m,v)c(m,v). This is why changing the drift from 1/21/2 to −1/2-1/2 preserves the constant, whereas removing the drift changes it.

Unconditional arithmetic asymptotics

Let F(X)\mathcal{F}(X) be the set of fundamental discriminants DD with 1<∣D∣≤X1<|D|\le X, of both signs, and let χD\chi_D be the primitive quadratic character of conductor ∣D∣|D|.

Theorem 1.1 (Quadratic Dirichlet family, unconditional). For each fixed η>0\eta>0, all but oη(X)o_{\eta}(X) elements of F(X)\mathcal{F}(X) satisfy, simultaneously,

max⁡C∈{Rdist,Rmult,S}∣CL(s,χD)log⁡log⁡∣D∣−cBM∣≤η.\max_{C\in\{R^{\mathrm{dist}},R^{\mathrm{mult}},S\}}\left|\frac{C_{L}(s,\chi_D)}{\log\log|D|}-c_{\mathrm{BM}}\right|\le\eta.

No hypothesis on zeros or central values is imposed.

The full signed family in this theorem requires an arithmetic argument at the prime 22. A theorem for the subfamily D=8dD=8d cannot simply be relabelled as a theorem for all fundamental discriminants. We give the complete extension of the mollified estimate, including the other residue classes and the cancellation of the paired primary terms, in the unconditional-family section.

For the Gaussian-integer family put π=1+i\pi=1+i. Let d∈Z[i]d\in\mathbb{Z}[i] range over elements that are prime to 22 and squarefree as ideals, with X/2<N(d)≤XX/2<N(d)\le X. Use the primitive quadratic Hecke character χπ5d\chi_{\pi^{5}d}. The finite conductor has norm 32N(d)32N(d), and the normalization used for the completion has conductor parameter Qd=128N(d)Q_d=128N(d). Each character occurs with exactly the two labels d,−dd,-d.

Theorem 1.2 (Quadratic Hecke family over Q(i)\mathbb{Q}(i), unconditional). For the preceding family, the three counts Rdist,Rmult,SR^{\mathrm{dist}},R^{\mathrm{mult}},S of L(s,χπ5d)L(s,\chi_{\pi^{5}d}) each equal

(cBM+o(1))log⁡log⁡Qd(c_{\mathrm{BM}}+o(1))\log\log Q_d

in density. More explicitly, at each fixed relative tolerance η>0\eta>0, the exceptional number of labels is oη(X)o_{\eta}(X). The same statement holds when each character is counted once and for cumulative norm cutoffs.

This is a specified quadratic Hecke family, rather than all Hecke characters over Q(i)\mathbb{Q}(i).

Let Hk\mathcal{H}_k be the set of normalized level-one holomorphic Hecke eigenforms of even weight kk, each counted once. The LL-function is normalized to have central point 1/21/2.

Theorem 1.3 (All even weights at level one, unconditional). As even k→∞k\to\infty, for each fixed η>0\eta>0, all but oη(∣Hk∣)o_{\eta}(|\mathcal{H}_k|) forms satisfy

max⁡C∈{Rdist,Rmult,S}∣CL(s,f)log⁡log⁡(k2)−cBM∣≤η.\max_{C\in\{R^{\mathrm{dist}},R^{\mathrm{mult}},S\}}\left|\frac{C_{L(s,f)}}{\log\log(k^{2})}-c_{\mathrm{BM}}\right|\le\eta.

The measure is unweighted. Both residue classes of even kk modulo 44 are included, and no bound on the central multiplicity is assumed.

The three further arithmetic families under GRH

The following families are considered separately; GRH for one is not used to prove a statement about another.

(i) Fix a primitive holomorphic cuspidal eigenform ff of even weight at least 2, fixed level, and trivial nebentypus. Let DD range over all signed fundamental discriminants. The target is the primitive automorphic twist L(s,f⊗χD)L(s, f \otimes\chi_D), whose conductor QD≍fD2Q_D \asymp_f D^2. The form ff may have complex multiplication.

(ii) Let KK range over non-Galois cubic fields of either fixed discriminant sign, without weights, and put LK(s)=ζK(s)/ζ(s)L_K(s) = \zeta_K(s)/\zeta(s). This is the entire degree-two standard Artin LL-function of the S3S_3-closure, with conductor QK=∣DK∣Q_K = |D_K|.

(iii) Let KK range over cyclic cubic fields, each once. If χ,χ‾\chi,\overline{\chi} are its two primitive cubic Dirichlet characters of conductor qq, put ZK(s)=L(s,χ)L(s,χ‾)=ζK(s)/ζ(s)Z_K(s) = L(s,\chi)L(s,\overline{\chi}) = \zeta_K(s)/\zeta(s). The conductor and field discriminant are QK=DK=q2Q_K = D_K = q^2.

In (i), the parameter is ∣D∣|D|; in (ii) and (iii), it is ∣DK∣|D_K|. A dyadic family means X/2<parameter≤XX/2 < \text{parameter} \le X. Write LX=log⁡XL_X = \log X, H=log⁡log⁡XH = \log\log X and HQ=log⁡log⁡QH_Q = \log\log Q. Constants below may depend on the fixed form in (i).

Theorem 1.4 (Uniform full-count estimate under family GRH). Assume GRH for the primitive LL-functions of the selected family (i), (ii), or (iii). In (iii) this means GRH for the primitive cubic characters. Set c=cBMc = c_{\mathrm{BM}} in (i) and (ii), and c=1/(π2)c = 1/(\pi\sqrt{2}) in (iii). For every fixed 0<ε<1/160 < \varepsilon< 1/16 there are constants Aε,Cε,Xε>0A_\varepsilon, C_\varepsilon, X_\varepsilon> 0 such that, for X≥XεX \ge X_\varepsilon and every deterministic real zz with

H−1/2+ε≤z≤1,H^{-1/2+\varepsilon} \le z \le1,

the original unweighted dyadic measure satisfies

PX{max⁡C∈{Rdist,Rmult,S}∣C−cHQ∣>AεzHQ}≤Cεlog⁡HHz2.(2)\mathbb{P}_X\left\{\max_{C\in\{\mathrm{Rdist},\mathrm{Rmult},S\}} |C-cH_Q|>A_\varepsilon zH_Q\right\}\le C_\varepsilon\frac{\log H}{Hz^2}. \tag*{(2)}

The constants are independent of zz. Central nonvanishing and simple zeros are not assumed.

The quantifier in (2) allows a choice z=z(X)z=z(X) in the indicated interval. It does not assert a single sample event for all zz. It concerns the full count in probability, not its variance.

For fixed η>0\eta>0, this gives an exceptional proportion Oη(log⁡H/H)O_\eta(\log H/H) outside relative tolerance η\eta. Two useful shrinking tolerances are

∣C−cHQ∣≤AHQ2/3(log⁡HQ)1/3,exception O((log⁡H/H)1/3),(3)|C-cH_Q|\le AH_Q^{2/3}(\log H_Q)^{1/3},\qquad\text{exception }O((\log H/H)^{1/3}), \tag*{(3)}
∣C−cHQ∣≤AεHQ1/2+ε,exception Oε((log⁡H)H−2ε).(4)|C-cH_Q|\le A_\varepsilon H_Q^{1/2+\varepsilon},\qquad\text{exception }O_\varepsilon((\log H)H^{-2\varepsilon}). \tag*{(4)}

These corollaries also hold for cumulative cutoffs: the exceptional counts are the displayed proportions times XX in (i),(ii) and times X\sqrt{X} in (iii). We do not assert an arbitrary-z(X)z(X) cumulative estimate without specifying its dyadic envelope.

The coefficientwise twist ∑n≥1λf(n)χD(n)n−s\sum_{n\ge1}\lambda_f(n)\chi_D(n)n^{-s} also satisfies the conclusions for (i). Its difference from the primitive twist is a fixed finite set of Euler factors. We retain the primitive conductor and the primitive GRH in this version; we do not assign the modified function a new primitive functional equation.

Individual complex cubic derivatives

The augmentation in (iii) is real. An individual cubic character instead gives a complex function on the real axis. A real zero of its derivative means a simultaneous zero of its real and imaginary parts; there is no associated sign-change statistic.

Theorem 1.5 (Complex cubic characters under cubic-family GRH). Let C(X)C(X) contain all primitive exact-order-three Dirichlet characters with X/2<qχ≤XX/2<q_\chi\le X, including both conjugates.

Assume GRH for this family. Let RχmultR_{\chi}^{\mathrm{mult}} count the real zeros of L′(s,χ)L'(s,\chi) on [1/2,1][1/2,1] with complex-analytic multiplicity. For every fixed 0<ε<1/160<\varepsilon<1/16,

References

  1. [1]A. O. L. Atkin and J. Lehner, Hecke operators on Γ0(m), Mathematische Annalen 185 (1970), 134–160.DOI
  2. [2]A. O. L. Atkin and Wen-Ch’ing Winnie Li, Twists of newforms and pseudo-eigenvalues of W-operators, Inventiones Mathematicae 48 (1978), 221–243.DOI
  3. [3]Jean-Marc Azaïs and Mario Wschebor, Level sets and extrema of random processes and fields, John Wiley & Sons, 2009, Theorem numbering checked in the authors’ manuscript.
  4. [4]Stephan Baier and Matthew P. Young, Mean values with cubic characters, 2010, arXiv:0804.2233v4, 3 November 2010.DOI
  5. [5]R. C. Baker and H. L. Montgomery, Oscillations of quadratic L-functions, Analytic Number Theory (Allerton Park, IL, 1989), Progress in Mathematics, vol. 85, Birkhäuser Boston, Boston, MA, 1990, pp. 23–40.DOI
  6. [6]Manjul Bhargava, Takashi Taniguchi, and Frank Thorne, Improved error estimates for the Davenport–Heilbronn theorems, 2023, arXiv:2107.12819v2, 19 July 2023.arxiv.org/abs/2107.12819
  7. [7]Peter J. Cho and Henry H. Kim, Moments of logarithmic derivatives of L-functions, Journal of Number Theory 183 (2018), 40–61.DOI
  8. [8]Peter Jaehyun Cho and Gyeongwon Oh, Counting cyclic extensions with local conditions and applications to L-values in the critical strip, Canadian Journal of Mathematics (2025), 1–39. First View, published online 8 August 2025.DOI
  9. [9]Brian Conrey, Andrew Granville, Bjorn Poonen, and K. Soundararajan, Zeros of Fekete polynomials, Annales de l’Institut Fourier 50 (2000), no. 3, 865–889.
  10. [10]J. B. Conrey and K. Soundararajan, Real zeros of quadratic Dirichlet L-functions, Inventiones Mathematicae 150 (2002), 1–44.DOI
  11. [11]Pranendu Darbar, Chantal David, Matilde Lalin, and Allysa Lumley, Asymmetric distribution of extreme values of cubic L-functions at s = 1, 2024, arXiv:2306.13626v2, 9 August 2024.arxiv.org/abs/2306.13626
  12. [12]Pierre Deligne, La conjecture de Weil. I, Publications Mathématiques de l’IHÉS 43 (1974), 273–307.
  13. [13]Peng Gao, The fourth moment of central values of quadratic Hecke L-functions in the Gaussian field, 2020, arXiv:2004.12528v1, 27 April 2020.arxiv.org/abs/2004.12528
  14. [14]——, Real zeros of quadratic Hecke L-functions, 2020, arXiv:2012.04836v1, 9 December 2020.arxiv.org/abs/2012.04836
  15. [15]Bob Hough, Zero-density estimate for modular form L-functions in weight aspect, Acta Arithmetica 154 (2012), no. 2, 187–216, Version consulted: arXiv:1109.1771v2, 28 November 2014.arxiv.org/abs/1109.1771
  16. [16]——, The distribution of the logarithm in an orthogonal and a symplectic family of L-functions, 2014, arXiv:1109.1783v2, 24 November 2014.arxiv.org/abs/1109.1783
  17. [17]Daniel R. Johnston and Andrew Yang, Some explicit estimates for the error term in the prime number theorem, 2022, arXiv:2204.01980v2, 20 April 2022.arxiv.org/abs/2204.01980
  18. [18]Oleksiy Klurman, Youness Lamzouri, and Marc Munsch, Sign changes of short character sums and real zeros of Fekete polynomials, 2024, arXiv:2403.02195v2, 5 September 2024.arxiv.org/abs/2403.02195
  19. [19]Dimitris Koukoulopoulos, The distribution of prime numbers, Graduate Studies in Mathematics, vol. 203, American Mathematical Society, 2019, Chapter 11 consulted in the author’s preliminary version.
  20. [20]Youness Lamzouri and Kunjakanan Nath, Real zeros of L′(s, χd), 2026, arXiv:2511.02774v2, 27 January 2026.arxiv.org/abs/2511.02774
  21. [21]Michel Ledoux, Measure concentration, transportation cost, and functional inequalities, 2003, Lecture notes, Edinburgh 2002 and Bonn 2003.
  22. [22]J ianya Liu and Yangbo Ye, Perron’s formula and the prime number theorem for automorphic L-functions, Pure and Applied Mathematics Quarterly 3 (2007), no. 2, 481–497.DOI
  23. [23]Paul D. Nelson, Bounds for standard L-functions, Author’s manuscript, 256-page version, accessed 14 October 2026.
  24. [24]Ian Petrow, Moments of L′(1/2) in the family of quadratic twists, 2012, arXiv:1208.4069v2, 12 November 2012.DOI
  25. [25]Arul Shankar, Anders Södergren, and Nicolas Templier, Central values of zeta functions of non-Galois cubic fields, Inventiones Mathematicae 243 (2026), no. 1, 33–116.arxiv.org/abs/2107.10900
  26. [26]Quanli Shen and Joshua Stucky, The fourth moment of quadratic Dirichlet L-functions II, 2024, arXiv:2402.01497v1, 2 February 2024.arxiv.org/abs/2402.01497

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