Scalar field collapse with negative cosmological constant
  The formation of black holes or naked singularities is studied in a model in which a homogeneous time-dependent scalar field with an exponential potential couples to four dimensional gravity with negative cosmological constant. An analytic solution is derived and its consequences are discussed. The model depends only on one free parameter, which determines the equation of state and decides the fate of the spacetime. Without fine tuning the value of this parameter the collapse ends in a generic formation of a black hole or a naked singularity. The latter case violates the cosmic censorship conjecture. 
R. Baier, Hiromichi Nishimura and S. A. Stricker
gr-qc hep-th