Testing the principle of equivalence with Planck surveyor
  We consider the effect of the violation of the equivalence principle (VEP) by the massive neutrino component on the Cosmic Microwave Background angular power specrum. We show that in the presence of adiabatic and isocurvature primordial density perturbations the Planck surveyor can place limits on the maximal VEP by the massive neutrino component at the level of 10^ -5, valid in the general relativity, for the case in which the gravity is the single source of VEP. This work has been performed within the framework of the {\sc Planck}/LFI activities. 
L.A. Popa, C.Burigana and N.Mandolesi (IASF/CNR, Bologna, Italy)