Particle-like solutions to higher-order curvature Einstein-Yang-Mills systems in d dimensions

We consider the superposition of the first two members of the gravitational hierarchy (Einstein plus first Gauss-Bonnet (GB)) interacting with the superposition of the first two members of the Yang-Mills (YM) hierarchy, in d dimensions. The YM fields are taken to be in the chiral representations of the gauge groups, (i) SO(±)(d), and (ii) SO(±)(d - 1), respectively, for (i) even d and (ii) odd d. Such systems can occur in the low energy effective action of string theory. Particle-like solutions in dimensions d = 6, 8, and d = 7, are constructed, respectively. Our results reveal qualitatively new properties featuring double-branch solutions with critical behaviour. In this preliminary study, we have restricted numerical study to one-node solutions.