Properties of enhançons in supergravity

Abstract

A certain class of naked singularities, related to N = 2 pure super Yang-Mills theory, are resolved in string theory with the enhançon mechanism. We study the properties of the enhançon in supergravity. Initially we consider the stability of the supergravity solutions. We study small perturbations of these solutions, constructing a sufficiently general ansatz for linearised perturbations of the non-extremal solutions, and show that the linearised equations are consistent. We investigate linearised perturbations of the horizon branch and the extremal solution numerically. We show that these solutions are stable against the perturbations we consider. This provides further evidence that these latter supergravity solutions are capturing some of the true physics of the enhançon. We show that the shell branch solutions violate the weak energy condition, and are hence unphysical. We extend the investigation of nonextremal enhançons, finding the most general solutions with the correct symmetry and charges. There are two families of solutions. One of these contains a solution with a regular horizon found previously; this previous example is shown to be the unique solution with a regular horizon. The other family generalises a previous nonextreme extension of the enhançon, producing solutions with shells which satisfy the Weak Energy Condition. We argue that identifying a unique solution with a shell requires input beyond supergravity.