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We study possible effects of Lorentz-violation on the generation ofcosmological perturbations at inflation by introducing a simple inflatingfive-dimensional brane-world setup with violation of four-dimensionalLorentz-invariance at an energy scale $k$. We consider massless scalar field,meant to mimic perturbations of inflaton and/or gravitational field, in thisbackground. At three-momenta below $k$, there exists a zero mode localized onthe brane, whose behaviour coincides with that in four-dimensional theory. Onthe contrary, at three-momenta above $k$, the localized mode is absent andphysics is entirely five-dimensional. As three-momenta get redshifted, moremodes get localized on the brane, the phenomenon analogous to ``modegeneration''. We find that for $k\gg H$, where $H$ is the inflationary Hubblescale, the spectrum of perturbations coincides with that in four-dimensionaltheory. For $k < H$ and time-dependent bulk parameters, the spectrum deviates,possibly strongly, from the flat spectrum even for pure de Sitter inflation.Comment: 5 figures, iopart, minor changes, appendix adde

Lorentz violation and cosmological perturbations: a toy brane-world model