Λ < 0 quantum gravity in 2 + 1 dimensions: II. Black-hole creation by point particles

Using the proposed formalism for Λ<0 quantum gravity in 2+1 dimensions, we study the process of black-hole production in a collision of two point particles. The creation probability for a BH with the simplest topology inside the horizon is given by the Liouville theory four-point function projected on an intermediate state. We analyse in detail the semi-classical limit of small AdS curvatures, in which the probability is dominated by the exponential of the classical Liouville action. The probability is found to be exponentially small. We then argue that the total probability of creating a horizon given by the sum of probabilities of all possible internal topologies is of order unity, so that there is no exponential suppression of the total production rate