A Study on the Vector Inflation in Bianchi Type I Cosmology

Some aspects of vector inflation have been studied, especially the effects of particle production on the slow-roll process, phase diagram and anisotropy. It is shown that owing to particle production, there is a peak in the phase diagram of the scalar field, and that the direction of the peak is independent of the initial condition and the variation of mass. While in the case of vector field, the direction of the peak depends on the value of mass. Correspondingly, the anisotropy of the system is promoted or suppressed. The degree of anisotropy is related not only to the slow-roll process, but also to the process of particle production after the process of slow-roll. Hence the particle production may be a cause of cosmic isotropy.