Scale dependences of local form non-Gaussianity parameters from a DBI   isocurvature field
  We derive the spectral indices and their runnings of local form $f_{NL}$ and $g_{NL}$ from a DBI isocurvature field and we find that the indices are suppressed by the sound speed $c_s$. This effect can be interpreted by the Lorentz boost from the viewpoint in the frame where brane is moving. 
Qing-Guo Huang and Chunshan Lin
astro-ph.CO gr-qc hep-ph hep-th