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Existence of multi-solitons with any parameters for the 5D energy critical wave equation

Yvan Martel, Frank Merle

TL;DR

This work proves the existence of multi-soliton solutions for the energy-critical focusing wave equation in dimension five with arbitrary numbers of solitons and parameter choices, addressing the challenge of algebraic soliton decay through a dimension-aware energy method. A refined approximate solution, together with a modulation and bootstrap framework, yields precise control of soliton interactions and the asymptotic behavior $\nabla u(t) \to \sum_k \nabla W_k^\infty$ as $t\to+\infty$. The authors also extend inelasticity results to general multi-soliton configurations under a non-vanishing interaction condition, employing a channel-of-energy analysis for the radial linear wave equation to show non-purity of the solution backward in time. Together, these results advance the understanding of multi-soliton dynamics, stability, and potential soliton-resolution phenomena in high-dimensional critical wave equations.

Abstract

For the focusing, energy critical wave equation in dimension 5, we construct multi-solitons with any number of solitons, any choice of signs, speeds, scaling parameters and translation parameters. This requires to revisit in depth previous constructions of multi-solitons based on a unidirectional approach, to fully take into account the dimension of the space and the possibility for solitons to move in any direction. Then, as a consequence of this more general construction and of the arguments developed in a previous article, the inelastic nature of any collision of solitons is proved under a non-cancellation assumption on the parameters.

Existence of multi-solitons with any parameters for the 5D energy critical wave equation

TL;DR

This work proves the existence of multi-soliton solutions for the energy-critical focusing wave equation in dimension five with arbitrary numbers of solitons and parameter choices, addressing the challenge of algebraic soliton decay through a dimension-aware energy method. A refined approximate solution, together with a modulation and bootstrap framework, yields precise control of soliton interactions and the asymptotic behavior as . The authors also extend inelasticity results to general multi-soliton configurations under a non-vanishing interaction condition, employing a channel-of-energy analysis for the radial linear wave equation to show non-purity of the solution backward in time. Together, these results advance the understanding of multi-soliton dynamics, stability, and potential soliton-resolution phenomena in high-dimensional critical wave equations.

Abstract

For the focusing, energy critical wave equation in dimension 5, we construct multi-solitons with any number of solitons, any choice of signs, speeds, scaling parameters and translation parameters. This requires to revisit in depth previous constructions of multi-solitons based on a unidirectional approach, to fully take into account the dimension of the space and the possibility for solitons to move in any direction. Then, as a consequence of this more general construction and of the arguments developed in a previous article, the inelastic nature of any collision of solitons is proved under a non-cancellation assumption on the parameters.
Paper Structure (19 sections, 19 theorems, 289 equations)

This paper contains 19 sections, 19 theorems, 289 equations.

Key Result

Theorem 1

Let $K\geq 2$. For all $k\in \{1,\ldots,K\}$, let $\lambda_k^\infty>0,$${\boldsymbol y}_k^\infty\in \mathbb{R}^5$, $\epsilon_k\in \{\pm1\}$ and ${\boldsymbol\ell}_k\in \mathbb{R}^5$ with $|{\boldsymbol\ell}_k|<1$ such that for any $k\neq m$, ${\boldsymbol\ell}_k\neq {\boldsymbol\ell}_m$. Let Then, there exist $T>0$ and a solution $u$ of eq:NW on $[T,+\infty)$, satisfying

Theorems & Definitions (37)

  • Theorem 1: Multi-solitons with any set of parameters
  • Corollary 1: Inelasticity and dispersion as $t\to-\infty$
  • Remark 1.1
  • Remark 1.2
  • Lemma 2.1
  • Remark 2.2
  • Lemma 2.3
  • proof
  • Lemma 2.4: MaM2
  • Remark 2.5
  • ...and 27 more