Quantum fluctuations of bulk inflaton in inflationary brane world

The inflationary scenario for the brane world driven by the bulk inflaton i s proposed. The quantum fluctuations of the inflaton is calculated and comp ared to those of the conventional 4-dimensional inflationary scenario. It i s shown that the deviation of the primordial spectrum of this model from th at of the conventional one is too small to be observed even if AdS radius i s very large. Hence, it turns out that the inflation caused by the bulk inf laton is viable in the context of brane world cosmology. (C) 2001 Published by Elsevier Science B.V.