The inflaton potential in four-dimensional theory is rather arbitrary, and fine-tuning is required generically. By contrast, inflation in the brane world scenario has the interesting feature that the inflaton potential is motivated from higher-dimensional gravity, or more generally, from bulk modes or string theory. We emphasize this feature with examples. We also consider the impact on the spectrum of density perturbation from a velocity-dependent potential between branes in the brane inflationary scenario. It is likely that such a potential can have an observable effect on the ratio of tensor to scalar perturbations. © 2001 Elsevier Science B.V. All rights reserved.
Shiu, G., & Tye, S. H. H. (2001). Some aspects of brane inflation. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 516(3–4), 421–430. https://doi.org/10.1016/S0370-2693(01)00950-9