Instability of $H^1$-stable peakons in the Camassa-Holm and Novikov equations

It is well-known that peakons in the Camassa-Holm equation and other integrable generalizations of the KdV equation are $H^1$-orbitally stable thanks to the presence of conserved quantities and properties of peakons as constrained energy minimizers. By using the method of characteristics, we prove that piecewise $C^1$ perturbations to peakons grow in time in spite of their stability in the $H^1$-norm. We also show that the linearized stability analysis near peakons contradicts the $H^1$-orbital stability result for the Camassa-Holm equation, hence the passage from the linear to nonlinear theory is false.Non UBCUnreviewedAuthor affiliation: McMaster UniversityFacult