Assisted inflation via tachyon condensation

In this paper we propose a new mechanism of inflating the Universe with non -BPS D4-branes which decay into stable D3-branes via tachyon condensation. In a single brane scenario the tachyon potential is very steep and unable t o support inflation. However, if the universe lives in a stack of branes pr oduced by a set of noninteracting unstable D4-branes, then the associated s et of tachyons. may drive inflation along our 3 spatial dimensions. After t achyon condensation the Universe is imagined to be filled with a set of par allel stable D3-branes. We study the scalar density perturbations and rehea ting within this setup. (C) 2001 Elsevier Science B.V. All rights reserved.