PIRSA:08060175

Probing the primordial helium abundance and the effective number of neutrino species with CMB

(2008). Probing the primordial helium abundance and the effective number of neutrino species with CMB. Perimeter Institute. https://pirsa.org/08060175

Probing the primordial helium abundance and the effective number of neutrino species with CMB. Perimeter Institute, Jun. 06, 2008, https://pirsa.org/08060175 

          @misc{ pirsa_PIRSA:08060175,
            doi = {10.48660/08060175},
            url = {https://pirsa.org/08060175},
            author = {},
            keywords = {Quantum Fields and Strings, Particle Physics, Cosmology},
            language = {en},
            title = {Probing the primordial helium abundance and the effective number of neutrino species with CMB},
            publisher = {Perimeter Institute},
            year = {2008},
            month = {jun},
            note = {PIRSA:08060175 see, \url{https://pirsa.org}}
          }
Talk numberPIRSA:08060175
DOI10.48660/08060175
Collection
Talk Type Conference
Subject

Abstract

We point out that light scalar fields with symmetries generically generate non-Gaussianity in the density fluctuations. Our observation makes the presence of the non-Gaussianity ubiquitous. When the inflationary scale and the properties of the scalar fields satisfy a certain relation, the non-Gaussianity becomes large enough to be observed by the ongoing and planned observations. We name such a particle responsible for a large non-Gaussianity as an \'ungaussiton\', and give explicit examples to realize the ungaussiton mechanism. We also derive a consistency relation between the bispectrum and the trispectrum, tau_NL = 10^3 f_NL^(4/3), which, if confirmed, will strongly support this mechanism.