Energy minimisers with prescribed Jacobian

TL;DR

This paper investigates conditions under which energy-minimizing maps with a prescribed Jacobian are symmetric and unique, revealing scenarios where symmetry fails and providing counterexamples to previous assumptions.

Contribution

It establishes a condition on the Jacobian function that guarantees symmetry and uniqueness of minimizers, and constructs explicit counterexamples where minimizers are non-symmetric.

Findings

Identifies a condition on the Jacobian ensuring symmetric minimizers.

Constructs explicit examples with non-symmetric minimizers.

Shows that prescribed boundary conditions do not guarantee symmetry.

Abstract

We study the symmetry and uniqueness of maps which minimise the $np$-Dirichlet energy, under the constraint that their Jacobian is a given radially symmetric function $f$. We find a condition on $f$ which ensures that the minimisers are symmetric and unique. In the absence of this condition we construct an explicit $f$ for which there are uncountably many distinct energy minimisers, none of which is symmetric. Even if we prescribe the maps to be the identity on the boundary of a ball we show that the minimisers need not be symmetric. This gives a negative answer to a question of H\'{e}lein (Ann. Inst. H. Poincar\'{e} Anal. Non Lin\'{e}aire 11 (1994), no. 3, 275-296).