Assisted chaotic inflation in brane-world cosmology

Assisted chaotic inflation in brane cosmology is discussed. We work in the framework of Randall-Sundrum (RS) II model, in which adopting the RS condition the only parameter is the five-dimensional Planck mass. Using the scalar spectral index and the amplitude of scalar perturbations we determine both the mass of the scalar fields responsible for inflation and the fundamental Planck mass of the higher-dimensional theory. We find that the mass of the scalars has the typical value of the inflaton mass in chaotic inflation ($M_I\sim {10}^{13}$ GeV) and that the five-dimensional Planck mass is very close to the GUT (Grand Unified Theories) scale ($M_5\sim ({10}^{16}-{10}^{17})$ GeV). Furthermore, no matter how many scalar fields we use it is not possible to have chaotic inflation with field values below the fundamental Planck mass.