Isocurvature modes in the CMB bispectrum
  We study the angular bispectrum of local type arising from the (possibly
correlated) combination of a primordial adiabatic mode with an isocurvature
one. Generically, this bispectrum can be decomposed into six elementary
bispectra. We estimate how precisely CMB data, including polarization, can
enable us to measure or constrain the six corresponding amplitudes, considering
separately the four types of isocurvature modes (CDM, baryon, neutrino density,
neutrino velocity). Finally, we discuss how the model-independent constraints
on the bispectrum can be combined to get constraints on the parameters of
multiple-field inflation models.
