arXiv:0903.5533v1 [hep-th] 31 Mar 2009 Degenerate and critical domain walls and accelerating universes driven by bulk particles A. de Souza Dutra a,b∗ , A.C. Amaro de Faria Jr. b and M. Hott b† a Abdus Salam ICTP, Strada Costiera 11, Trieste, I-34100 Italy. b UNESP-Campus de Guaratinguet´ a-DFQ ‡ Departamento de F´ ısica e Qu´ ımica 12516-410 Guaratinguet´ a SP Brasil November 18, 2018 Abstract We consider a scenario where our universe is taken as a three-dimensional domain wall embedded in a five-dimensional Minkowski space-time, as originally proposed by Brito and collaborators [1]. We explore the existence of a richer class of soliton solutions and their consequences for the acceleration of the universe driven by collisions of bulk particle excitations with the walls. In particular it is shown that some of these solutions should play a fundamental role throughout the expansion process. PACS numbers: 11.27.+d, 11.10.Lm, 95.35.+d, 98.80.Cq * E-mail: dutra@feg.unesp.br † e-mail: hott@feg.unesp.br ‡ Permanent Institution 1