From the invariance of the generalized space-time non-commutative commutation relations, local Poincaré and general coordinate transformations are derived. Moreover, a generalized Dirac equation is obtained. Applied to the de Sitter universe, it is shown that the space-time non-commutativity contributes to the particle creation process and induces a Casimir-like effect.

We improve the previous study of the Klein-Gordon equation in a non-commutative space-time as applied to the Hydrogen atom to extract the energy levels, by considering the second-order corrections in the non-commutativity parameter. Phenomenologically we show that non-commutativity is the source of lamb shift corrections.

Using the approach of the modified Euler-Lagrange field equation together with the corresponding Seiberg-Witten maps of the dynamical fields, a noncommutative Dirac equation with a Coulomb potential is derived. We then find the noncommutative modification to the energy levels and the possible new transitions. In the nonrelativistic limit a general form of the hamiltonian of the hydrogen atom is obtained, and we show that the noncommmutativy plays the role of spin and magnetic field which gives the hyperfine structure.

This study is about the application of the noncommutativity on the DKP equation up to first-order in [Formula: see text] for the process of pair creation of spin-1 particles from vacuum in [Formula: see text] curved space–time. The density of particles created in the vacuum can be calculated with the help of the Bogoliubov transformations. The noncommutative density of created particles is found to decrease as [Formula: see text], so that the rate of particle creation increases whenever a noncommutativity parameter is small and this corresponds to the spirit of quantum mechanics.