Preprint
Inserted: 20 sep 2025
Last Updated: 20 sep 2025
Year: 2025
Abstract:
Weak solutions $m\colon\Omega\subset\mathbb R^2\to\mathbb R^2$ of the eikonal equation
\[
m
=1\text{ a.e. and }\mathrm{div}\: m =0\,,
\]
arise naturally as sharp interface limits of bounded energy configurations in various physically motivated models, including the Aviles-Giga energy.
The distributions $\mu_\Phi=\mathrm{div}\,\Phi(m)$, defined for a class of smooth vector fields $\Phi$ called entropies, carry information about singularities and energy cost.
If these entropy productions are Radon measures, a long-standing conjecture predicts that
they must be concentrated on the 1-rectifiable jump set of $m$ -- as they do if $m$ has bounded variation (BV) thanks to the chain rule.
We establish this concentration property, for a large class of entropies, under the Besov regularity assumption
\[
m\in B^{1/p}_{p,\infty} \quad
\Leftrightarrow
\quad
\sup_{h\in \mathbb R^2\setminus\lbrace 0\rbrace} \frac{\
m(\cdot +h)-m\
_{L^p}}{
h
^{1/p}} <\infty\,,
\]
for any $1\leq p<3$, thus going well beyond the BV setting ($p=1$) and leaving only the borderline case $p=3$ open.
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