English

Small cap decoupling for the parabola with logarithmic constant

Classical Analysis and ODEs 2025-01-30 v2

Abstract

We note that the subpolynomial factor for the qLp\ell^qL^p small cap decoupling constants for the truncated parabola P1={(t,t2):t1}\mathbb{P}^1=\{(t,t^2):|t|\leq 1\} may be controlled by a suitable power of logR\log R. This is achieved by considering a suitable amplitude-dependent wave envelope estimate, as was introduced in a recent paper of Guth and Maldague to demonstrate a small cap decoupling for the (2+1)(2+1) cone; we demonstrate that the version for P1\mathbb{P}^1 may be taken with a loss controlled by a power of logR\log R as well.

Cite

@article{arxiv.2305.00125,
  title  = {Small cap decoupling for the parabola with logarithmic constant},
  author = {Ben Johnsrude},
  journal= {arXiv preprint arXiv:2305.00125},
  year   = {2025}
}

Comments

34 pages. This version includes a broad/narrow step missing in a previous version. Wave packets have been tweaked. Improved exposition in overview. Various small numerical changes. Central claims are unchanged, except for updated numerology. The author thanks Zane Li and Po-Lam Yung for pointing out the major error to be corrected in previous version. Comments on current version are welcome

R2 v1 2026-06-28T10:21:19.769Z