Scalar particles in the adjoint representation of a non-Abelian gauge theory play an importantrole in many scenarios beyond the standard model, especially of GUT type. For such theories manifestly gauge-invariant, massless, composite vector particles have been predicted, even at weak coupling, using the Fröhlich-Morchio-Strocchi mechanism. We use lattice gauge theory to investigate the simplest such theories, a single adjoint scalar coupled to an SU(2) Yang-Mills theory. The results support the existence of such a particle, in accordance with the prediction.