BPS sphalerons in the F2 nonlinear sigma model

We construct static and also time-dependent solutions in a nonlinear sigma model with target space being the flag manifold F-2 = SU(3)/U(1)(2) on the four-dimensional Minkowski spacetime by analytically solving the second-order Euler-Lagrange equation. We show that the static solutions saturate an energy lower bound and can be derived from coupled first-order equations though they are saddle-point solutions. We also discuss basic properties of the time-dependent solutions.