On the conjugacy classes in maximal unipotent subgroups of simple algebraic groups. (Q862261)

Let \(G\) be a simple algebraic group over an algebraically closed field \(k\) of characteristic \(p\geq 0\). Assume that \(p\) is zero or good for \(G\). Let \(U\) be the unipotent radical of a Borel subgroup. Using relative Steinberg isomorphisms, adjoint orbits of \(U\) on its Lie algebra are analyzed.