Harmonic maps, Backlund-Darboux transformations and "line soliton" analogs

Harmonic maps from ${\text{BR}}^2$ or one-connected domain $\text{O}\subset {\text{BR}}^2$ into $GL(m,\text{BC})$ and $U(m)$ are treated. The GBDT version of the B"acklund-Darboux transformation is applied to the case of the harmonic maps. A new general formula on the GBDT transformations of the Sym-Tafel immersions is derived. A class of the harmonic maps similar in certain ways to line-solitons is obtained explicitly and studied.