Particle Acceleration on the Background of the Kerr-Taub-NUT Spacetime
  We study the collision of two particles with the different rest masses moving
in the equatorial plane of a Kerr-Taub-NUT spacetime and get the center-of-mass
(CM) energy for the particles. We find that the CM energy depends not only on
the rotation parameter, $a$, but also on the NUT charge of the Kerr-Taub-NUT
spacetime, $n$. Especially, for the extremal Kerr-Taub-NUT spacetime, an
unlimited CM energy can be approached if the parameter $a$ is in the range
$[1,\sqrt{2}]$, which is different from that of the Kerr and Kerr-Newman black
holes.
