Multisoliton solutions and blow up for the $L^2$-critical Hartree equation
Jaime Gómez, Tobias Schmid, Yutong Wu
TL;DR
The paper addresses the long-time and blow-up dynamics of the $L^2$-critical Hartree equation in four dimensions by constructing multisoliton solutions whose cores follow an $m$-body Newton-type law with inverse-square interactions. The authors extend the Krieger–Martel–Raphaël and Wu framework to a nonlocal Hartree setting, using a refined approximation and modulation strategy to align the multi-soliton entities with hyperbolic or parabolic trajectories and to control degeneracies in generalized root spaces. Through a pseudo-conformal transformation, they derive finite-time blow-up at multiple points (or a single point) with the sharp rate $\|\nabla u(t)\|_{L^2} \sim |t|^{-1}$, and provide precise modulation/evolution estimates that close a bootstrap argument. This work connects $m$-body dynamics with nonlocal dispersive PDE behavior, offering new insights into multisoliton interactions and blow-up mechanisms in critical Hartree-type equations.
Abstract
We construct multisoliton solutions for the $L^2$-critical Hartree equation with trajectories asymptotically obeying a many-body law for an inverse square potential. Precisely, we consider the $m$-body hyperbolic and parabolic non-trapped dynamics. The pseudo-conformal symmetry then implies finite-time collision blow up in the latter case and a solution blowing up at $m$ distinct points in the former case. The approach we take is based on the ideas of [Krieger-Martel-Raphaël, 2009] and the third author's recent extension. The approximation scheme requires new aspects in order to deal with a certain degeneracy for generalized root space elements.
