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Main Authors: Park, Jeongheon, Kwon, Soonsik, Kim, Taegyu
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2508.07787
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author Park, Jeongheon
Kwon, Soonsik
Kim, Taegyu
author_facet Park, Jeongheon
Kwon, Soonsik
Kim, Taegyu
contents We study the blow-up dynamics for the $L^2$-critical focusing half-wave equation on the real line, a nonlocal dispersive PDE arising in various physical models. As in other mass-critical models, the ground state solution becomes a threshold between the global well-posedness and the existence of a blow-up. The first blow-up construction is due to Krieger, Lenzmann and Raphaël, in which they constructed the minimal mass blow-up solution at the threshold mass. In this paper, we construct finite-time blow-up solutions with mass slightly exceeding the threshold. This is inspired by similar results in the mass-critical NLS by Bourgain and Wang, and their instability by Merle, Raphaël and Szeftel. We exhibit a blow-up profile driven by the rescaled ground state, with a decoupled dispersive radiation component. We rigorously describe the asymptotic behavior of such solutions near the blow-up time, including sharp modulation dynamics. Furthermore, we demonstrate the instability of these solutions by constructing non-blow-up solutions that are arbitrarily close to the blow-up solutions. The main contribution of this work is to overcome the nonlocal setting of half-wave and to extend insights from the mass-critical NLS to a setting lacking pseudo-conformal symmetry.
format Preprint
id arxiv_https___arxiv_org_abs_2508_07787
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Blow-up construction and instability for mass-critical half-wave equation with slightly superthreshold mass
Park, Jeongheon
Kwon, Soonsik
Kim, Taegyu
Analysis of PDEs
We study the blow-up dynamics for the $L^2$-critical focusing half-wave equation on the real line, a nonlocal dispersive PDE arising in various physical models. As in other mass-critical models, the ground state solution becomes a threshold between the global well-posedness and the existence of a blow-up. The first blow-up construction is due to Krieger, Lenzmann and Raphaël, in which they constructed the minimal mass blow-up solution at the threshold mass. In this paper, we construct finite-time blow-up solutions with mass slightly exceeding the threshold. This is inspired by similar results in the mass-critical NLS by Bourgain and Wang, and their instability by Merle, Raphaël and Szeftel. We exhibit a blow-up profile driven by the rescaled ground state, with a decoupled dispersive radiation component. We rigorously describe the asymptotic behavior of such solutions near the blow-up time, including sharp modulation dynamics. Furthermore, we demonstrate the instability of these solutions by constructing non-blow-up solutions that are arbitrarily close to the blow-up solutions. The main contribution of this work is to overcome the nonlocal setting of half-wave and to extend insights from the mass-critical NLS to a setting lacking pseudo-conformal symmetry.
title Blow-up construction and instability for mass-critical half-wave equation with slightly superthreshold mass
topic Analysis of PDEs
url https://arxiv.org/abs/2508.07787