Skyrme term
= Skyrme term
{c}
{title2=$\mathcal L_4=\frac1{32e^2}\operatorname{tr}([L_\mu,L_\nu][L^\mu,L^\nu])$}
The particular quartic-derivative interaction in the <Skyrme model>, with $L_\mu=U^\dagger\partial_\mu U$. Its static energy is positive and scales inversely with soliton size, opposing collapse under <Derrick scaling>. It is one choice of four-derivative mesonic interaction, not the whole general fourth-order <chiral perturbation theory> Lagrangian.