Late-Time Tails in Gravitational Collapse of a Self-Interacting   (Massive) Scalar-Field and Decay of a Self-Interacting Scalar Hair
  We study analytically the initial value problem for a self-interacting (massive) scalar-field on a Reissner-Nordstr\"om spacetime. Following the no-hair theorem we examine the dynamical physical mechanism by which the self-interacting (SI) hair decays. We show that the intermediate asymptotic behaviour of SI perturbations is dominated by an oscillatory inverse power-law decaying tail. We show that at late-times the decay of a SI hair is slower than any power-law. We confirm our analytical results by numerical simulations. 
Shahar Hod and Tsvi Piran