Correction to the laser master equation

The effects of the interaction between atoms and a laser field on the damping phenomena of the laser system are examined by the perturbational treatment of the rigorous damping theory. Correction terms to the conventional master equation of the laser system are obtained and those to the equations of motion for moments are also calculated. The significance of the correction terms is explicitly shown. The modified conditions of threshold and diffusion constant are derived by eliminating the atom variables near the threshold in terms of the boson coherent-state representation. Remarks on the conventional Langevin-equation approach are also made.