Collision of spinning particles near BTZ black holes

We study the collision property of spinning particles near a Banados-Teitelboim-Zanelli (BTZ) black hole. Our results show that although the center-of-mass energy of two ingoing particles diverges if one of the particles possesses a critical angular momentum, however, particle with critical angular momentum can not exist outside of the horizon due to the violation of timelike constraint. Further detailed investigation indicates that only the particle with a subcritical angular momentum is allowed to exist near an extremal rotating BTZ black hole and the corresponding collision center-of-mass energy can be arbitrarily large in a critical angular momentum limit.