Pure leptonic decays of the B-c meson and their radiative corrections - art. no. 114013

The one-loop radiative corrections to the pure leptonic decay B-c-->l nu(l) are presented. We treat the infrared divergences appearing in the loop cal culations together with those in the radiative decay B-c-->l nu(l)gamma. Th e divergences are finally canceled by each other to make the results finite . It is emphasized that the radiative decay may be separated properly from the pure leptonic decays. We can compare our results with the experimental measurements directly as long as the theoretical "softness" of the photon c orresponds to the experimental resolutions. Furthermore with the nonrelativ istic constituent quark model, the typical long distance contributions to t he radiative decays are estimated, and it is shown that the contributions a re negligible in comparison with the accuracy of one-loop corrections and t he expected experimental measurements. [S0556-2821(99)05319-9].