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An Integral Mean Value Theorem for Weyl Sums over Broken Arcs

Number Theory 2026-08-05 v1

Abstract

In this article, we research the mean value of integral of exponential sum S(α)=uIe(αuk)S(\alpha)=\sum_{u\in I}e(\alpha u^k), where II is a short interval whose length is 2Nθ,θ<12N^{\theta},\theta<1, and the broken arc m\mathfrak{m^*} is a subset of a following minor arcs m=jk1{α:q<(logN)A,h<q,(h,q)=1,αhq>1qN(kj1/2)θ} \mathfrak{m}=\bigcap_{j\leq k-1}\left\{\alpha:\forall q<(\log N)^A,h<q,(h,q)=1,\Big|\alpha-\frac{h}{q}\Big|>\frac{1}{qN^{(k-j-1/2)\theta}}\right\} which has measure at least c>0c>0. By setting mm is a sufficiently large number, NN is be sufficiently large in terms of mm. When k>logmk>\log m and logklogm<1/2\frac{\log k}{\log m}<1/2 we set the following estimate: mN1<u<N2e(zuk)mdzcNθm(2k+12k+2+o(1)) \int_{\mathfrak{m^*}}\bigg|\sum\limits_{{N_1}<u<{N_2}}{e(zu^k)}\bigg|^{m}\mathrm{d}z\ll_cN^{\theta m(\frac{2k+1}{2k+2}+o(1))} We can find this estimate moving beyond the even-odd restriction of powers. To get this bound, we first set a strong estimate for almost α\alpha by Diophantine approximation and Vinogradov's main value theorem. Then, combining this result, we construct a refined Weyl differencing argument by partitioning the differences step into large and small range, which significantly outperforms the classical one. By the version of probability, we can calculate the multiplicity of each sum. Put them together and we can complete the proof.

Keywords

Cite

@article{arxiv.2608.04948,
  title  = {An Integral Mean Value Theorem for Weyl Sums over Broken Arcs},
  author = {YaoJie Guo},
  journal= {arXiv preprint arXiv:2608.04948},
  year   = {2026}
}