Magnetic solutions in AdS5 and trace anomalies

We discuss black hole and black string solutions in d = 5 Einstein-Yang-Mills theory with negative cosmological constant, proposing a method to compute their mass and action. The magnetic gauge field of these configurations does not vanish at infinity. We argue that this implies a nonvanishing trace for the stress tensor of the dual d = 4 theory. (c) 2007 Elsevier B.V. All rights reserved.