Time-Space Noncommutativity And Symmetries For A Massive Relativistic   Particle
  We show the existence of a time-space noncommutativity (NC) for the physical system of a massive relativistic particle by exploiting the underlying symmetry properties of this system. The space-space NC is eliminated by the consideration of the exact symmetry properties and their consistency with the equations of motion for the above system. The symmetry corresponding to the noncommutative geometry turns out to be the special case of the gauge symmetry such that the mass parameter of the above system becomes noncommutative with the space and time variables. The possible deformations of the gauge algebra between the spacetime variables and the angular momenta are discussed in detail. These modifications owe their origin to the NC of the mass parameter with the space and time variables. The cohomological origin for the above NC is addressed in the language of the off-shell nilpotent Becchi-Rouet-Stora-Tyutin (BRST) symmetry transformations. 
R. P. Malik (Bose National Centre)