CPT breaking in noncommutative Magueijo-Smolin model

We review an instance of noncommutative geometry based on a specific realization of the model of doubly special relativity proposed by Magueijo and Smolin (MS) on noncommutative spacetime. In particular, we discuss the Hopf algebra associated to it, which has not been considered in the literature till now. We show that the momentum sector of this model can be viewed as a particular basis of the \kp model. An interesting property is that the MS Hamiltonian is not invariant under the reversal of the sign of the energy, and in particular it is not invariant under the standard definition of charge conjugation. Therefore, if following Dirac one identifies the negative energy states with antiparticles, their mass differs from that of particles. We examine the possible consequences of this fact in the context of first quantization and discuss its interpretation from the point of view of quantum field theory, taking into account possible alternative definitions of charge conjugation proposed in the noncommutative framework.