2026/07/30 by Taegyu Kim, Soonsik Kwon, Jeongheon Park
Mathematics · #math.AP #msc:35B44 #msc:35Q55 #msc:35Q41
29 pages
arxiv created 2026/07/30 · arxiv updated 2026/07/31
We study finite-time blow-up for the one-dimensional focusing mass-critical half-wave equation i∂tu=|D|u-|u|2u. For even initial data with negative energy and mass slightly above the ground-state mass, we prove the log-log upper bound ‖u(t)‖ H1/2\lesssim ((log|log(T-t)|)/(T-t))1/2 as t\uparrow T. This gives, for the half-wave equation, the same log-log law upper bound as in the mass-critical nonlinear Schrödinger equation. The proof follows a similar strategy developed by Merle and Raphaël, but requires a new construction of the blow-up profile. Main difficulty arises from the nonlocal operator |D| and the absence of pseudo-conformal symmetry. We construct an almost self-similar profile with exponentially small error by combining tail computations carried out to arbitrary order, depending on a dynamical parameter, with Borel integral summation in Λ-analytic spaces. Then, in the modulation analysis, we use a local-virial spectral property proved in the companion paper \citePark2026arXiv.